IAQ guidelines for selected volatile organic compounds (VOCs) in the UK

Building and Environment 165 (2019) 106382

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IAQ guidelines for selected volatile organic compounds (VOCs) in the UK a

a,∗

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C. Shrubsole , S. Dimitroulopoulou , K. Foxall , B. Gadeberg , A. Doutsi

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T

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Air Quality & Public Health Group, Environmental Hazards and Emergencies Department, Centre for Radiation, Chemical and Environmental Hazards, Public Health England, Harwell Science and Innovation Campus, Chilton, Oxon, OX11 0RQ, UK General Toxicology Group, Toxicology Department, Centre for Radiation, Chemical and Environmental Hazards, Public Health England, Harwell Science and Innovation Campus, Chilton, Oxon, OX11 0RQ, UK

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ARTICLE INFO

ABSTRACT

Keywords: Volatile organic compounds VOC Indoor air quality TVOC Building regulations Guidelines

Poor indoor air quality, can cause a variety of adverse health effects. Pollutant exposure levels inside buildings are likely due to pollutants from both indoor and outdoor sources. Although there are many indoor airborne pollutants, the current review focusses on Volatile Organic Compounds (VOCs), and considers the current Total Volatile Organic Compounds (TVOC) standards alongside other guideline values, to control levels within the indoor environment. We reviewed the current scientific data showing the occurrence of various VOCs in buildings internationally, and the available toxicological reviews for the individual VOCs with potential for adverse health effects that require attention. We considered available health-based general population indoor guidelines for long and short-term exposure in respect of individual compounds, including acetaldehyde, αpinene, D-limonene, formaldehyde, naphthalene, styrene, tetrachloroethylene, toluene and xylenes (mixture). We conclude individual VOC guidelines are the most appropriate way forward and that TVOC can be used as an indicator for indoor air quality. This study highlights which compounds should be prioritised for monitoring purposes. Our findings inform discussions around the improvement of general population health, source control and the need to raise awareness of the potential impacts of pollutants in the home.

1. Introduction Given that the UK population spend around 80–90% of their time in buildings and around 60% in their homes [1,2], buildings are important modifiers of population health [3]. Overall exposure levels inside buildings are due to pollutants from both indoor and outdoor sources, although some attenuation by buildings occurs. There are a variety of pollutants in the indoor environment, including gaseous pollutants (inorganic chemicals, radon and volatile organic compounds (VOCs)), biological pollutants (allergens, viruses and bacteria, mould) and particulate matter (PM). The current work focusses on VOCs in the indoor environment from both indoor and outdoor sources. The presence of VOCs in residential and public buildings are well reported (e.g. [4]. Health organisations (e.g. The World Health Organisation, The US Environmental Protection Agency and Public Health England) have assessed the evidence and listed the potential health effects of VOCs, including irritation of the eyes and respiratory tract, allergies and asthma, central nervous system symptoms, liver and kidney damage, as well as cancer risks. The health risks from VOCs are determined by the level of exposure experienced as well as the time spent within indoor environments (the focus of this study).

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Thus, there is a need for health-based guidance values. As defined in the building standard [5], VOCs are the organic compounds eluting between and including n-hexane and n-hexadecane on the gas chromatographic column. Very volatile organic compounds (VVOCs) are the volatile organic compounds eluting before n-hexane on the gas chromatographic column. Semi-volatile organic compounds (SVOCs) are the organic compounds which elute after n-hexadecane, on the gas chromatographic column. Total volatile organic compounds (TVOCs) are the sum of the concentrations of the identified and unidentified VOCs. All compounds listed in Annex G of BS EN16516:2017 are to be regarded as VOC, even if they elute from the gas chromatographic system before n-hexane or after n-hexadecane. These include aromatic hydrocarbons, saturated aliphatic hydrocarbons (n, -iso, cyclo-), terpenes, aliphatic alcohols, aromatic alcohols, glycols, glycolethers and aldehydes. Formaldehyde (HCHO) is of greatest importance, due to its prevalence in the indoor environment and its known health impacts [6]. In outdoor air, the primary VOC sources include those from incomplete combustion e.g. road traffic exhaust gases and volatile byproducts of various industrial and commercial operations, as well as biological metabolism, decay and degradation processes [7]. In indoor

Corresponding author. E-mail address: [email protected] (S. Dimitroulopoulou).

https://doi.org/10.1016/j.buildenv.2019.106382 Received 6 June 2019; Received in revised form 27 August 2019; Accepted 28 August 2019 Available online 11 September 2019 0360-1323/ © 2019 Elsevier Ltd. All rights reserved.

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air, VOCs are widely emitted from construction and building products (e.g. paints, varnishes, waxes and solvents), household consumer products (detergents, cleaning products, air fresheners and personal care products) as well as those emitted during the use of electronic devices such as photocopiers and printers (e.g. [8–11]. Secondary pollutants can also be formed, for example by ozone-initiated chemistry of terpenes and degradation (e.g. [12–14]. [8] concluded that, depending on the building type and age, building materials alone represented approximately 40% of indoor VOC sources, excluding consumer products, fixtures and fittings, and other occupant activities. Compared to outdoor air, indoor VOC sources in the UK potentially have greater health significance, due to the time people spend in various buildings, the confined nature of the space and the proximity to source, compared to exposure in the outdoor air [15,16]. Previous studies combining indoor and outdoor measurements have suggested that indoor generated VOCs have a significant contribution to occupant exposure, often between 2 and 10 times higher than those outdoors [17]. Various projects have highlighted concentrations of VOCs in both homes and workplaces (e.g. [8,18–22], and that VOC concentrations in new or renovated buildings can be several orders of magnitude higher than those in older buildings [23–26]. Given the presence of VOCs in residential and public buildings and their potential health impacts, prioritisation of airborne pollutants and individual VOCs considered for monitoring campaigns and proposing guideline values has been carried out by various researchers and expert groups (e.g. [27,28] – INDEX project [29,30]; – ENVIE project). These European projects led to the development of the World Health Organisation (WHO) indoor air quality (IAQ) guidelines for selected pollutants in 2010 [6], which were intended for use in countries with no relevant regulations for general population exposure. Some countries have made real advances in mitigating indoor air pollution and set guidelines for indoor air contaminants in recent years (e.g. Germany, Canada, Japan and the Flemish Government). The UK only uses TVOC as a measure, France and California use individual VOCs, whilst others such as Germany and Canada use a combination of both. In the UK there are currently no indoor air quality (IAQ) guidelines for individual VOCs. In their absence, the recently revised building guidance BB101: “Ventilation, thermal comfort and indoor air quality in schools” from the Department for Education [31] recommended the use of the WHO IAQ guidelines [6] . Approved Document F of the UK Building Regulations includes maximum concentration guidelines for inorganic pollutants, as well as Total Volatile Organic Compounds (TVOC), which is used as a measure to give a possible indication of indoor air quality [32]. TVOC has also been proposed as an indicator for the calculation of actual building ventilation rate, e.g. [33]. However, TVOC as a measure reveals little regarding the nature of the individual compounds, their concentrations and possible toxicity. Within individual studies, TVOC is either determined as the total integrated peak area calibrated with the use of toluene as a reference compound in ISO16000-6, or alternatively, may be determined by summing the individual concentrations of every identified component between n-hexane and n-hexadecane [34,35]. However, there are varying degrees of uncertainty in individual VOC and TVOC measurements. In some studies, it is uncertain if this has been considered within the analysis, as the analytical methods were either unclear or lacked sufficient detail to make accurate judgement. ISO 16000-6:2011 specifies analytical methods for VOCs in indoor air, building products or materials and other products used in indoor environments [36] based on sampling on Tenax TA sorbent tubes, thermal desorption and gas chromatography: 1) Quantitative analysis uses standards of the specific compound (VOC) of interest. A calibration curve for the compound is derived and unknown samples quantitated against the curve. An uncertainty for measurements can be quoted for individual VOCs, including relative humidity (RH) and temperature if recorded, or a standard uncertainty factor is applied across all samples and added to the calibration uncertainty (e.g. [37]. In addition, it is

good practice to provide a blank for each location and VOC measured to ensure that any contamination due to transport and handling can be quantified [8]. 2) Qualitative analysis (identification and estimation) can be used when the compounds present are not specified, or a quantitative result is not required. Estimation is by reference to a toluene calibration curve [37]. Estimated results are useful for trend analysis but cannot be regarded as an ‘exact’ compound measurement. There are cost benefits in using the qualitative method, which may be sufficient for some studies but where precision of measurement is required the quantitative method should always be used. Existing studies have used both methods, however quantitative values have been used in this study. The overall objective of this work is to propose health-based IAQ guidelines for individual VOCs in the UK. The starting point was the 2010 WHO IAQ guidelines for selected VOCs and our first step was to identify what were the important individual VOCs to consider and their emission sources; for this purpose, we carried out a systematic literature review. Having identified the individual VOCs, the next step was to propose the most appropriate guideline values by reviewing the evidence base of existing guidelines reported and applied worldwide. The proposed VOC guideline values would inform any revision of the UK Building Regulations. 2. Materials and methods-review methodology 2.1. Scope We carried out a systematic literature review of recent research evidence on the measurements of VOCs in indoor residential and public buildings (offices), focussing on the UK and Europe but also worldwide. The school environment was out of the scope of this project as it was considered as part of the Sinphonie project [38]. To identify the individual compounds, we considered their presence in the relevant indoor environments, their sources, concentrations, toxicity and health impacts. The individual VOCs identified for which we propose IAQ guidelines, are emitted from construction products and building materials; however, since most monitoring studies are carried out post-occupancy, the contribution of VOCs from consumer products are also considered here. We reviewed the evidence base of existing health-based guidelines proposed by other countries and organisations, to identify which existing guidelines could be adopted for individual VOCs. We did not aim to carry out a full systematic review of the primary toxicological evidence, to produce new guidelines. However, the selection process involved the critical review of the studies considered by each organisation, including the selection of the critical endpoint, and the uncertainty factors (e.g. consideration of susceptible groups) used by the authoritative bodies to derive the health-based guidance values. We selected the most appropriate existing health-based guideline values (HBGVs) for inhalation and propose these as UK IAQ guidelines. In reviewing the ROBINS-I tool criteria for possible study bias [39], we acknowledge that, possible missing data and the selection of specific case-studies may have led to some possible bias. In the case of naphthalene there is emerging toxicological data that may change proposed guideline values. However, it has yet to be reviewed by an authoritative body (e.g. PHE, US EPA) and it was outside the scope of this project to derive new HBGVs, our focus was to report on existing evidence. 2.2. Search strategy The review of VOC monitoring studies followed the PRISMA methodology [40]. The literature search included the following aspects and disciplines: building physics, IAQ and ventilation, VOC emissions from construction and consumer products, field studies of concentrations for individual VOCs - with a focus on statistically significant or large-scale monitoring studies, health effects, international HBGVs. The 2

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Fig. 1. Review flow chart.

and scope of study. (e.g. reported on various factors that impact VOC concentration, in addition to the measurements taken including: seasonal variations, indoor/outdoor (I/O) ratios, ventilation rates of buildings, selected building material, in- field emissions measurements, clear limits of detection for compounds and occupant activity questionnaires). Further evidence was obtained from the derivation of health-based guidance values, to clarify the impact of individual VOCs on human health. Interactions between VOCs and other known airborne pollutants in the indoor air from both indoor and outdoor sources were noted (e.g. reactions with ozone (O3) [41]). Strategies for VOC reduction/removal from the indoor air were considered as well as suggested methods of mitigation, which were included in the evidence base. Studies that failed to meet these criteria were considered not relevant to the review and were excluded.

following electronic databases were investigated: Scopus (including citation reports), Elsevier, Google Scholar, PubMed, Ovid Embase, EBSCO Global Health, TRIP and NICE Evidence. Furthermore, we investigated the grey literature, including the European Union, UK and other government legislative and policy documents, national and international VOC guidelines for indoor air, technical data sheets and specifications, published textbooks, reports from organisations involved in the investigation of VOC emissions from construction and consumer products and the refurbishment process, and recognised websites (for example those from manufacturing organisations were employed to identify further peer-reviewed studies). Using this framework, an initial set of keywords was developed to explore the literature. Additional terms and search strings revealed by the literature search were added and investigated. These are detailed in the appendix. Studies emerged that indicated specific VOCs being emitted from construction, fixtures and fittings and consumer products into the ambient air and their stated concentrations. Specific VOCs were further investigated to ascertain whether any known health impacts due to exposure were noted along with the range of concentrations seen in field studies.

2.4. Analysis The findings of included studies were grouped to characterise individual VOCs and permitted health-based guideline values from national and international standards and their measured concentrations in buildings, in relation to toxicological data and consequent health impacts. Studies reporting mean and/or minimum, maximum values for the compounds of interest were considered in data analysis, which were stratified according to building type. Two building types were included: 1) residential housing and 2) offices. No restriction was placed upon the method of analysis used for the identification and quantification of VOCs. However, emphasis has been given to research demonstrating robust, clear methodologies and analysis using established protocols (e.g. ISO-16000 series) and indicating any measurement uncertainties. These findings were tabulated summarising the VOCs present. Most studies were carried out post-occupancy, therefore included sources from consumer products, however distinction has been made between existing and ‘new’ buildings (defined by the studies as those less than 5 years old). Where seasonality was examined (ventilation behaviour), this was noted. The range of

2.3. Document selection criteria, inclusions and exclusions The search was limited to studies published in the English language from 2000 to 2018. However, one monitoring/field study from 1996 has been added due to its status as the first large-scale UK based investigation. Included studies investigated connections between generated VOCs, their concentrations and possible sources in the indoor and outdoor air. Studies investigating new builds, refurbishment to upgrade or improve the energy efficiency of buildings were reviewed, including studies that considered building airtightness/air-change-rates, seasonality and their impacts on VOC concentrations. To be statistically significant only large-scale monitoring studies were investigated (i.e. those with more than around 40 buildings), following the example adopted by [4]. The study by [8] considered the ‘gold standard’ for investigation, in terms of its level of detail, transparency of investigation, scale 3

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VOCs of interest were investigated and their distribution of concentrations in the indoor air noted.

butoxyethanol and hexanal were removed at this stage as they were not identified in the case studies and furthermore no HBGVs were identified for these compounds. In the case of hexanal, this compound may be important in the future due to its prevalence on wooden buildings [57]. As new compounds are emerging, a VOC scan during field studies is an important method for identifying these and new trends and tendencies as they arise. The values shown in Table 4 are health-based guidelines founded on cancer or non-cancer toxicological endpoints or a combination depending on the VOC involved. This table is for comparison of existing values in various countries only and not for the selection of the proposed HBGVs in the UK. The IAQ guidelines for individual VOCs are stated in terms of concentrations (μg.m−3), for both short and longterm exposures, for those compounds considered the most hazardous by individual countries. There is some agreement in terms of the focus on certain VOCs, but also wide-ranging values shown for both short and long-term exposure. This may be partly due to the date that some guidelines were established, with differences in approach and more recent data being used to provide different derivations, as shown in the notes below the table. Additionally, study types can have different health endpoints e.g. cancer or non-cancer outcomes. Following WHO guidelines for indoor air [6], only inhalation routes and resulting outcomes are considered in this study. As previously noted, the UK has no indoor health-based guidelines for individual VOCs with known health impacts at low concentrations, and the UK guideline value for TVOCs is 300 μg m−3, as stated in the current Building Regulations Approved Document F (ADF); ventilation [32].

3. Results Initially, 7,958 papers were retrieved in the searches. These included duplicated publications across the eight databases investigated. A total of 1,257 duplicates, and a further 5,159 documents were removed as not relevant to the study following a screening of title and abstracts, with 1,164 studies excluded for not meeting the review criteria, such as small study scale, building types (e.g. schools), unclear or limited methodologies. This left 378 papers for full review. Ultimately, 71 sources were included in this review (Fig. 1). 3.1. VOCs in homes, offices and public buildings 3.1.1. Summary of VOCs identified in major studies Medium to large-scale monitoring/field studies of buildings are vital to ascertain the individual VOCs present. These can help inform the decision-making process, by comparing these to toxicologically-based guideline values in indoor air, to determine which compounds can be excluded and those that might be included in guidance for regulation. A summary of the compounds most commonly seen across all major studies is shown Table 1. This table indicates those VOCs that are considered a priority for investigation by the authors of the reports and those that were not. This is indicated by ‘High’ or ‘Low’ for the compounds seen in the individual studies. Some studies e.g. Index [28], indicate that further research is required for some compounds (αpinene and D-limonene). Table 1, which presents the data in chronological order, shows that later studies have clearly suggested some VOCs as high priority that should be included in health-based guidelines.

3.3. Indoor exposure limits in building design certifications and independent research projects (μg.m−3) Various monitoring and modelling studies have considered emissions from consumer products [12,18,58–60]. [18]; as part of the Europe-wide ‘Emissions, Exposure Patterns and Health Effects of Consumer Products in the EU-funded (EPHECT) project [18] completed detailed health risk assessments on VOCs from consumer products, to establish critical exposure limits (CELs). These CELs represent a healthbased inhalation limit for a specific pollutant and are generally applicable either where no national or international guidelines (e.g. WHO) exist and are shown in Table 5 along with those suggested by the Annex 68 worldwide study on emissions in both low and non-low energy buildings [21], and the Index project [28]. It is important to quantify VOC concentrations from consumer products, as virtually all studies are carried out post-occupancy, and the contribution of VOCs from consumer products represents a large component of individual indoor exposure in addition to VOCs emitted from construction products and other sources or activities such as decorating [21]. There are several building accreditation/certification schemes that establish performance criteria, based in part on the reduction of VOC sources and appropriate ventilation strategies such as the WELL standard v2 [65], and Leadership in Energy and Environmental Design [66]. WELL seeks to use medical evidence to influence design, by stipulating the use of low/non-emissive materials, cleaning and consumer products, whereas LEED is a widely used green building rating system including embodied carbon and other sustainability criteria. Ventilation performance criteria for mechanical systems specific to high performance green (low energy) buildings also exist (e.g. [67], as well as those for designers and installers of heating, ventilation and air conditioning services in UK buildings (e.g. [68]. Both developed standards for specific VOCs (see Table 5) although the methodology used to derive these values is unclear from the documentation. Such standards are increasingly used by building and ventilation designers. The values in table are simply reporting current standards for comparison only, not for selection for HBGVs.

3.1.2. VOC emission sources in homes and offices Data from the European Chemicals Agency (ECHA), the World Health Organisation (WHO), United States Environmental Protection Agency (US EPA), PubCHEM and relevant major studies were investigated to establish the range of possible emission sources occurring in homes and offices (Table 2). 3.1.3. Identifying individual VOCs through measurements in homes and offices Monitoring/field studies with more than around 40 samples, both in the UK and internationally, were reviewed to identify the individual VOCs present in homes and offices. These include: TVOCs, 2-butoxyethanol, acetaldehyde, acrolein, α-pinene, benzene, chloroform, D-limonene, ethylbenzene, formaldehyde, hexanal, naphthalene, n-hexane, propionaldehyde, styrene, tetrachloroethylene, toluene, trichloroethylene and xylenes (as a mixture, as studies mainly treat all xylenes together and do not distinguish between the three isomers: mxylene o-xylene and p-xylene). Tables 3a-3l shows the results of the literature review and monitoring/field study analysis including the range of concentrations, study sample sizes, environment, location and source of values for each of the individual VOCs as well as those studies considering TVOCs. VOCs based on occurrence in buildings from major studies. 3.2. National and international health-based indoor guideline values for VOCs in homes and offices Having established the VOCs present in homes and offices/public buildings, internationally, a comparison of the various national and international health guidelines for these indoor environments are shown in Table 4, in chronological order to show the progression of research, understanding and focus. Of the VOCs identified in Table 1, 24

High

High

TVOC 2-Butoxyethanol Acetaldehyde Acrolein α-Pinene

Benzene Chloroform D-Limonene

5 High

Low

Low High

Low

Low

High

High

High

High

High

Further research needed

High

Further research needed High High

High

BUMA Project [8,10]

Public buildings/ Residential (+Schools)

Low

b

Index Project [28]

Residential

High

High

High

THADE -EFA 2002–2004 [43]

Residential

High

High High

High

Low High

High Low

Low

High

Lawrence Berkley [44]

Residential

Low

Low

Under evaluation

Low

Low High Low

High

High

High

Low High

AIRMEX Study [45]

Public buildings/ Residential (+Schools)

High

High

High

Low High

EPHECT Project [18]

Residential

High

High

High

High

Low High Low

High

High

High

High Low High

High

IEA EBC Annex 68 (2016)d

[46] c unpublished UK study High

Low-energy/non low-energy residential and public buildings

Residential

‘High’ and ‘Low’ refer to statements of priority for compounds seen in individual studies, i.e. those compounds that authors felt required monitoring and those they did not. ∗ WHO proposed guidelines include benzo(a)pyrene. However, reviewed studies show no evidence of its occurrence in domestic or office environment. a BRE study large study, limited range of species measured, as seen in large TVOC concentration compared to relatively small measured species concentration. b Priorities in the INDEX project are stated as based on occurrence, dose-response relationship. c MHCLG unpublished study. Qualitative method used (toluene equivalent concentration according to ISO 16000-6), species present but quantity subject to large uncertainties. d IEA study based on large scale measured values- occurrence only.

Ethylbenzene Formaldehyde Hexanal Naphthalene n-Hexane Propionaldehyde Styrene Tetrachloroethylene (T4CE) Toluene Trichloroethylene Xylenes

BRE study [42]

Project/case study

a

Residential

Building types

Table 1 Summary of VOCs present in homes and offices using UK and major international studies (> 40 buildings).

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Combination of species Automobile emissions, foods and beverages

Perfumes, cleaning products and deodorants.

Automobile emissions, solvents, tobacco smoking, scented candles, scatter rugs and carpet glue

Naturally occurring in citrus fruit peels/ fragrance constituent

TVOC Acetaldehyde (75-07-0)

α-Pinene (80-56-8)

Benzene (71-43-2)

D-Limonene

Furniture and wood products MDF, insulating materials, textiles

Smoking, residential wood, combustion, insecticide or pest repellent

Packaging, building and household products, smoking, rubber and epoxy adhesives, occurs naturally in various fruits, vegetables, nuts and meats

Formaldehyde* (50-00-0)

Naphthalene (91-20-3)

Styrene (100-42-5)

(5989-27-5)

WHO, USEPA, PubCHEM Suggested sources

VOC Species

Used in washing & cleaning products, air care products, biocides (e.g. disinfectants, pest control products) and polishes and waxes. Used in adhesives and sealants, coating products, fillers, putties, plasters, modelling clay, inks and toners, polymers, fuels, biocides (e.g. disinfectants, pest control products), polishes and waxes, washing & cleaning products and cosmetics and personal care products. Other release to the environment of this substance is likely to occur from: indoor use (e.g. machine wash liquids/detergents, automotive care products, paints and coating or adhesives, fragrances and air fresheners) ECHA has no public registered data indicating whether or in which chemical products the substance might be used Used in fillers, putties, plasters, modelling clay and coating products. Release to the environment of this substance can occur from industrial use: for thermoplastic manufacture. Other release to the environment of this substance is likely to occur from: indoor use (e.g. machine wash liquids/detergents, automotive care products, paints and coating or adhesives, fragrances and air fresheners) and outdoor use resulting in inclusion into or onto a materials (e.g. binding agent in paints and coatings or adhesives)

Combination of species ECHA has no public registered data indicating whether or in which chemical products the substance might be used used in: washing & cleaning products, biocides (e.g. disinfectants, pest control products), air care products, polishes and waxes, perfumes and fragrances and cosmetics and personal care products. Other release to the environment of this substance is likely to occur from: indoor use (e.g. machine wash liquids/detergents, automotive care products, paints and coating or adhesives, fragrances and air fresheners) ECHA has no public registered data indicating whether or in which chemical products the substance might be used.

Consumer product use of species [7],

Table 2 Material and product emission sources for selected VOCs in the indoor environment.

6

Present but source uncertain Not measured

Present but source unclear.

Laminate flooring, linoleum, varnished wood, cork, acrylic and water based paints, matt emulsion, plaster, wallpaper, wood- furniture particle board, plywood and chipboard

Combustion related, some minor possible re-emission by laminate flooring, acrylic and water based paints, matt emulsion Species definitely present, likely consumer product related

Species definitely present, likely consumer product related

Combination of species Wooden-pressed products, wall and floor coverings and paints.

Sourcesb residential and public buildings [8]. (BUMA)

Not present

Flooring, wood products. Also, possible reaction product due to ozone initiated reactions with terpene species. Seen especially in summer campaign

Cleaning agents and air fresheners

Fossil fuel combustion by traffic related or industrial sources (e.g. power plants)

Wood-based products, perfumes, cleaning products and deodorants, air fresheners

Combination of species Likely from human activities rather than building materials

Sourcesa offices [19]. [20] (OFFICAIR)

(continued on next page)

Not measured

Not measured

Laminate flooring, linoleum, wood- furniture: particle board, plywood and chipboard (Higher levels seen in newer homes).

Not measured

Likely combustion related

Not measured

Combination of species Not measured

Sources residential buildings [42]. (BRE)

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7

Paint removers, cleaners, glues, suede protectors

Automobile emissions, polishes, nail polish, synthetic fragrances, paint, scented candles, paint thinner, adhesives and cigarette smoke

Metal cleaning and degreasing agents, dry cleaning, breakdown product from Tetrachloroethylene Fugitive emissions from industrial sources, car exhaust, solvents markers, paint, floor polish and cigarette smoke

Tetrachloroethylene (12718-4)

Toluene (108-88-3)

Trichloroethylene (71-0106)

ECHA has no public registered data indicating whether or in which chemical products the substance might be used Used in lubricants and greases, polishes and waxes, anti-freeze products, nonmetal-surface treatment products, inks and toners, biocides (e.g. disinfectants, pest control products), textile treatment products and dyes, leather treatment products, adhesives and sealants and fuels. Other release to the environment of this substance is likely to occur from: indoor use (e.g. machine wash liquids/detergents, automotive care products, paints and coating or adhesives, fragrances and air fresheners), outdoor use, indoor use in close systems with minimal release (e.g. cooling liquids in refrigerators, oil-based electric heaters) and outdoor use in close systems with minimal release (e.g. hydraulic liquids in automotive suspension, lubricants in motor oil and break fluids) ECHA has no public registered data indicating whether or in which chemical products the substance might be used Used in lubricants and greases, polishes and waxes, adhesives and sealants, antifreeze products and biocides (e.g. disinfectants, pest control products). Other release to the environment of this substance is likely to occur from: indoor use (e.g. machine wash liquids/detergents, automotive care products, paints and coating or adhesives, fragrances and air fresheners), outdoor use, indoor use in close systems with minimal release (e.g. cooling liquids in refrigerators, oil-based electric heaters) and outdoor use in close systems with minimal release (e.g. hydraulic liquids in automotive suspension, lubricants in motor oil and break fluids)

Consumer product use of species [7],

Plaster, paint, particle board and various adhesives

Present but source uncertain

Present but source uncertain Plaster and various adhesives, plus external sources. No seasonality observed in xylene concentrations

Carpets, general furnishing.

Present but source uncertain

Sourcesb residential and public buildings [8]. (BUMA)

Possible external sources from vehicles, although higher winter concentrations may point to indoor sources such as paints and various adhesives predominating.

Present but source uncertain

Sourcesa offices [19]. [20] (OFFICAIR)

Not measured

Not measured

Plaster, painting and wallpapering

Not measured

Sources residential buildings [42]. (BRE)

b

It is proposed that occurrence of a percentage of some compounds may be an artefact due to reaction of ozone (O3) with the Tenax sorbent used to measure the VOC. Some indoor sources seen as primarily outdoor sourced pollutants may be in whole or part re-emitted sorbed VOCs. Further source apportionment studies are needed with reference to chamber emission tests where other sources are excluded.

a

Xylenes-mixture (133020-7)

WHO, USEPA, PubCHEM Suggested sources

VOC Species

Table 2 (continued)

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Table 3a TVOC concentrations (μg.m−3) observed in indoor environments. G Mean

Median

415.0 210.0 137.0 195.0 304.5 319.5 44.3 64.3 48.6 100.0 120.0 328.0 a

Max

Min

1688.0 3360.0 713.0 629.0 455.0 443.0 336.3 600.9 281.8 575.0 840.0

79.0 15.0 48.0 53.0 154.0 190.9 1.0 (est.) 1.0 (est.) 7.7 0.1

SD

95th percentile

106.0 146.0

1010.0

130.0 199.0 720.0

Study Sample

Monitoring Period

Environment

Location

Source

182 876 32 33 3,601 22,783 148 140 111 90 471 1125 292

4 weeks 4 weeks 2 weeks 2 weeks Various Various 5 days 5 days 1 week 8 h–7 days 20mins/1yr 24 h 24 h

Homes Homes Homes Living room Homes Main bedroom Low energy homes Non-low energy homes Offices (Summer) Offices (Winter) Public buildings Homes Decorated Homes Homes New Homes

UK UK UK UK Worldwide (incl. UK/Europe) Worldwide (incl. UK/Europe) Europe Europe Europe Australia Xi'an, China Japan Japan

[42] [47] [15] [15] [21] [21] [20] [20] [48] [49] [50] [24] [24]

a

Selected VOC were measured in this study. As such, the total VOC figure is not necessarily representative of TVOC.

3.4. VOC product labelling schemes

guidelines for maximum concentrations during the testing of emissions from building materials at the production stage: ECA Report No 29 [35].

With respect to indoor-generated pollutants, it has long been recognised that source control is the primary strategy to improve indoor air quality for all pollutant species, with ventilation aiming to remove and disperse any residual concentrations. Good IAQ is dependent on reducing outdoor ingress by good design, including effective ventilation strategies, whilst also focussing on the operation of the building in use and reducing emissions from indoor sources. European countries have developed the ‘Lowest Concentration of Interest’ (LCI) approach as a strategy for assessing the health effects of VOCs emitted from building materials [69]. Its intention was to provide a basic scheme to evaluate VOC emissions from building products as first discussed in ECA Report No 18 [70], which recommended that the LCI should be derived based on either air quality guideline values (AQG) or occupational exposure limits as auxiliary parameters for the assessment of the health risks resulting from exposure to chemicals emitted from building materials. This concept was adopted and developed as a protocol for a harmonised approach of a health-related evaluation of VOC emissions from building products measured in environmental chambers, under specific conditions [11,71,72]. Subsequently, the European Commission developed a list of compounds and defined their maximum allowable concentrations (LCI) for material emission testing. LCIs are not exposure limits, but

3.5. Establishing toxicological evidence and selection of health-based guidance values for individual VOCs For the purposes of this project, toxicological evidence was assessed from evaluations by authoritative bodies. Sources of information included The Agency for Toxic Substances and Disease Registry (ATSDR), Health Canada, the US EPA and the WHO. Current health-based inhalation guidance values derived by these authoritative bodies were reviewed and values, considered to be suitably protective of health, were selected as the proposed indoor air quality guidelines (Table 6). The selection process was based on judgement of the critical studies, including the selection of the critical endpoint, and the uncertainty factors (e.g. consideration of susceptible groups) used by the authoritative bodies to derive the health-based guidance values. Limonene and α-pinene have not been evaluated by the authoritative bodies listed above therefore the long-term CELs from the EPHECT project [18] were selected as the proposed indoor air quality guidelines for these compounds.

Table 3b Acetaldehyde (75-07-0) concentrations (μg.m−3) observed in indoor environments. G Mean

Max

Min

SD

14.0

69.0

3.0

18.0

54.0

5.0

13.5 14.8 10.1

20.0 25.1

8.7 8.7

94.6 16.0 12.0 29.1 41.3 41.6

1.8 < LODa < LOD 1.4 3.7 0.7

113.0 88.0

4.5 3.0

6.4 4.9 8.5 12.8 22.0 20.0 22.3 24.6 26.6 a

Median

11.6 11.0

17.7 18.8

Study Sample

Monitoring Period

Environment

Location

Source

8.0

32

2 weeks

UK

[51]

11.0

33

2-weeks

UK

[51]

3,601 22,783 61 567 490 148 140 186 96 60 1181 211 50 50 50

Various Various 72 h 7 days 7 days 5 days 5 days 7 days 7 days 7 days 2 h–6 months 24–72 h 24 h 24 h 5 days

Homes Living room Homes Main bedroom Low energy homes Non-low energy homes Homes/Apartments Homes/Apartments Homes/Apartments Offices (Summer) Offices (Winter) Public buildings Homes Homes and Public Buildings Homes New Homes Homes (Summer) Homes (Winter) Homes

Worldwide (incl. UK/Europe) Worldwide (incl. UK/Europe) Paris Paris Paris Europe Europe Europe Europe Europe USA USA Alberta, Canada Alberta, Canada Windsor, Canada

[21] [21] [52] [53] [54] [20] [20] [45] [45] [8] [44] [44] [55] [55] [56]

1.8

95th percentile

30.0

40.0 61.0

< LOD = below limit of detection.

8

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Table 3c α-pinene (80-56-80) concentrations (μg.m−3) observed in indoor environments. G Mean 16.5 68.7 18.5 10.7 4.1 15.7 17.9 10.2 31.7 4.2 6.3 3.2 14.5 37.0 140.0 36.0 269.0 47.0 9.7 8.0 9.5 a b

Median

15.53

2.5 8.0 4.7 3.5

Max

Min

140.0 57.0

11.8 4.8

854.3 66.0 68.0 47.3 214.1

0.0 < LODa < LOD 0.0 0.2

650.0 800.7 72.0 94.0

< LOQb 0.41 0.4 0.22

SD

95th percentile

23.5 13.2 6.9 23.7 52.3 15.9 51.9

51.0 572.0

90.0 61.0

Study Sample

Monitoring Period

Environment

Location

Source

40 3,601 22,783 42 47 188 41 46 2,242 148 140 160 97 5365 211 1125 292 49 96 50 50

24 h Various Various 48 h 48 h 48 h 48 h 48 h 4 weeks 5 days 5 days 7 days 7 days 2 h–6 months 24–72 h 24 h 24 h 24 h 7 days 24 h 24 h

Homes Low energy homes Non-low energy homes Homes Homes Homes Homes Homes Homes/Apartments Offices (Summer) Offices (Winter) Public buildings Homes Homes New Homes Homes New Homes Homes Homes Homes (Summer) Homes (Winter)

Oxford Worldwide (incl. UK and Europe Worldwide (incl. UK and Europe Athens Basel, Helsinki Milan Prague Leipzig Europe Europe Europe Europe USA USA Japan Japan Japan Canada Alberta, Canada Alberta, Canada

[61] [21] [21] [61] [61] [61] [61] [61] [62] [20] [20] [45] [45] [44] [44] [24] [24] [63] [64] [55] [55]

< LOD = Below limit of detection. < LOQ = Below limit of quantification.

properties in Avon and six properties in Hertfordshire over a year, taking passive measurements every month in five rooms within each building to allow for occupant ventilation behaviour and seasonality. TVOCs and formaldehyde were measured, limiting the scope of the study in terms of individual pollutant identification. Annual mean TVOC concentrations were greater than the ADF (2010) limit value (300 μg m−3) for all properties and 25% of homes were over 500 μg m−3. The large BRE study [42,47], investigating UK homes (n = 876), found mean concentrations of 210 μg m−3, but extremely high maximum levels with a 95th percentile of 1010 μg m−3. In the largest study [21], as part of the IEA-ESB Annex 68 project monitored 25,844 homes (houses and apartments), from 10 countries including European Union (EU) member states including the UK, of which 3,061 were low energy buildings (LEB) broadly built in line with both Approved Documents L1A/1B conservation of fuel and power in existing/ new dwellings [81] and ADF, 2010 regulations, and 22,783 buildings considered non-low-energy buildings (NLEB). In both cases, annual mean TVOC concentrations were in excess of the current UK regulation value of 300 μg m−3. It is noteworthy that LEBs, which are generally more airtight, showed little overall variation in TVOC concentrations when compared to NLEB buildings. This may be in part due to the construction materials used, low emission fixtures and fittings or the addition of purpose-provided ventilation, as opposed to uncontrolled ventilation in some NLEBs. For acetaldehyde, even maximum values seen in the various studies are all below the proposed 280 μg m−3 long-term limit proposed in Table 6 although, as with other compounds there are variations in the monitoring periods used to calculate the means in different studies. For a-pinene and D-limonene, in all the studies concentrations are below the long -term CELs proposed by [18]. However, Ozone (O3)-initiated reactions with terpenes, such as a-pinene and D-limonene, which are emitted during household use consumer products [10,14] produce gaseous and aerosol- phase products, including particles and formaldehyde amongst others, which can cause irritation of the respiratory system. The WHO states that no safe level of benzene exposure can be recommended because it is a genotoxic carcinogen. The concentrations of airborne benzene associated with an excess lifetime cancer risk of 1/10 000, 1/100 000 and 1/1 000 000 are 17, 1.7 and 0.17 μg m−3 [6]. From the 38 studies seen, 2 had mean values above 17 μg m−3, 27 above 1.7, whilst all the remainder were above 0.17 μg m−3. It is noted that the

4. Discussion This review has established the occurrence of indoor and outdoor sources of emissions for the relevant individual VOCs using data from ECHA, WHO, US-EPA, PubCHEM and source apportionment from studies, where VOC sources have been specifically located. Having established a list of suggested pollutants for monitoring and their proposed health-based guidance values (Table 6), statistically representative field studies were investigated to establish the indoor concentrations seen and how these relate to the proposed VOCs and the health-based guideline values. This review has also identified a body of literature exploring the health impacts of VOCs in the indoor environment of homes and offices. It has clarified the various standards around the world and proposed health based IAQ guidelines considering the most appropriate current evaluations by authoritative bodies. The derivation of new health-based guideline values and a systematic review of the toxicological data on the highlighted VOCs was outside the scope of this review. It is acknowledged there are some limitations in this review. The search strategy focussed on a broad range of keywords. It is accepted that some papers may have been missed as authors use titles or keywords not necessarily corresponding with the search parameters. However, despite this, sufficient evidence has been established to assist policy makers. It is recognised that any proposed approach to changes in current guidance must also consider other air pollutants, with VOCs being viewed as part of an optimal strategy for improving overall IAQ. 4.1. Comparison of results from monitoring studies with the proposed indoor health-based guidelines As previously stated in most monitoring/field studies, TVOC concentrations have not been measured and cannot be calculated, as no indication is given of the distribution of the different VOC concentrations among individual buildings. Of the eight studies listed in Table 3a, three show mean concentrations for TVOC values greater than the ADF standard (2010) and all the studies show maximum values above this. There is, as expected, variation between winter and summer TVOC concentrations, likely primarily due to ventilation behaviour. Concentrations in homes are generally higher than those in offices and public buildings, with new or newly decorated homes having some of the highest levels. The UK based BRE study [42], monitored 174 9

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Table 3d Benzene (71-43-5) concentrations (μg.m−3) observed in indoor environments. G Mean

Median

3.6 3.0 2.0 4.5 18.7 2.1 1.6 1.9 10.1 l 2.7 2.2 17.0 8.0 2.8 1.5 1.5

2.8 2.5 1.4 3.5 1.2 1.9 (1.6–2.3) 1.7 1.1 1.8 16.3

Min

93.5

< 0.1

16.8

0.9

120.0

1.4

5.0 7.0 61.0

4.2

Study Sample

Monitoring Period

Environment

Location

Source

40 876 155 3,601

24 h 4 weeks 12 h Variable

Homes Homes Homes Low energy homes

[61] [47] [58] [21]

22,783

Variable

Non-low energy homes

188 188 44 555 42 50

72 h 72 h 4 weeks 4 weeks 48 h 5 days

Non-smoking homes Smoking homes Homes Homes Homes Homes

Oxford UK UK Worldwide (incl. UK and Europe) Worldwide (incl. UK and Europe) Helsinki Helsinki Germany Germany Athens Athens

47 188 41 46 204 204 567 490 2,242 60

48 h 48 h 48 h 48 h 7 days 7 days 7 days 7 days 4 weeks 7 days

Basel Helsinki Milan Prague Erfurt Hamburg Paris Paris Leipzig Europe

111 148 140 186

7 5 5 7

Homes Homes Homes Homes Homes Homes Homes/Apartments Homes/Apartments Homes/Apartments Homes and Public Buildings Public buildings Offices (Summer) Offices (Winter) Public buildings

[73] [73] [74] [75] [61] Chatzis et al. (2005) [61] [61] [61] [61] [76] [76] [53] [54] [62] [8]

Europe Europe Europe Europe

[48] [20] [20] [45]

Study Sample

Monitoring Period

Environment

location

Source

14.7

96 4400 206 387 1393 96 3857 50 50 50 152

7 days 2 h–6 months 24–72 h 24 h 8 h–7 days 7 days 7 days 24 h 24 h 5 days 24 h

Europe USA USA Perth Australia Canada Canada Alberta Alberta Windsor, Canada Beijing

[45] [44] [44] [77] [49] [64] [78] [55] [55] [56] [79]

5.7

255

24 h

Beijing

[79]

0.1 1.6

471 107 50 602 602

uncertain 3h 24 h 24 h 24 h

Homes Homes New Homes Homes Homes Homes Homes-National Survey Homes (Winter) Homes (Summer) Homes Homes renovated within 5 years Homes renovated over 5 years ago Decorated Homes New Apartments Homes Homes (winter) Homes (summer)

Xi'an China Korea Japan Japan Japan

[50] [25] [63] [80] [80]

3.4 2.4

95th percentile

14.6

7.7

1.7 1.9 23.4 4.6 2.1 2.0 1.1

22.8 31.6 10.2

< LOD 0.0 0.1

63.7 10.0 8.9 63.7

0.7 < LOD* < LOD 0.5

Max

Min

32.1

0.4

1.2

125.0 22.4

< LOD 0.1

1.2 0.6

10.0 7.2

0.4 0.2

Median

< LOD-1.3

9.7 3.9 3.2 2.4 1.3

SD

7.8

9.5

5.5 1.4 2.1 4.4 Mean

Max

0.0

20.0

0.0

2.7

17.0

0.7

7.2 1.76

SD

95th percentile 10.0 4.6

days days days days

[21]

* < LOD = Below limit of detection.

The age of the buildings and their fixtures and fittings (possible sources of formaldehyde) are not stated in most studies, (the exception being [24], which may contribute to the higher values seen (possibly newer properties) along with the impacts of higher summer temperatures, as elevated indoor temperature will result in increased VOC emissions [85,86]. [17] suggest that aldehydes in homes can be the product of ozone-initiated reactions, later confirmed in the monitoring study of formaldehyde by [87]. [49] collated 31 separate studies from Australia and noted that very few studies investigated housing during the first five years of construction, when most off-gassing from new materials typically occurs. Generally, in Table 3f, most studies show mean values that are above the proposed long-term (1 year) guideline of 10 μg m−3. As all measurements were carried out within the monitoring period of 24hours- 7 days, and there is no guideline value to compare against, the closet guideline value is the long-term 1-year value of 10 μg m−3. The

current Department for Environment Food & Rural Affairs [82] national air quality objectives for benzene in England and Wales (also the focus of ADF, 2010) is an annual mean of 5 μg m−3 based on the EU ambient air quality directive (2008/50/EC) [83]. However, whilst acknowledging the practicalities of reducing ambient airborne pollution by improving ventilation in buildings, the focus of this study is to provide health-based guidance founded on toxicological research. [21] show that formaldehyde concentrations vary hugely with building type, whilst [20] demonstrate seasonal variation in exposure, primarily driven by occupant ventilation (window opening) behaviour. For VOCs in general, the studies show higher indoor concentrations in the winter, indicating higher contributions from indoor sources and lower external sources, with the opposite occurring in the summer. Formaldehyde is an exception to this rule and shows significantly higher concentrations in summer, a finding also seen in both [8,84]. 10

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Table 3e −3 D-limonene (5989-27-5) concentrations (μg.m ) observed in indoor environments. G Mean 19.0 6.2 25.0 27.8 32.9 78.3 15.0 30.7 71.5 27.1 4.7 19.0 9.4 29.2 23.0 13.0 28.2 28.1 47.0 30.0 31.0 35.0 a b

Median

Max

Min

16.0

308.4 39.8 49.3 65.0

< 0.1 13.0 9.5

34.0 81.0 175.7 422.9 159.4

< LODa < LOD 0.0 0.0

478.0 329.9 365.0 250.0

0.17 1.63 0.14 < LOQb

12.5 28.5 31.0 13.0

SD

95th percentile

28.6

51.0

121.0 19.4 61.5 150.5 26.4

110.0 41.0

25.0 32.0

Study Sample

Monitoring Period

Environment

Location

Source

40 876 3,601 22,783

24 h 4 weeks Variable Variable 4 weeks 48 h 48 h 48 h 48 h 48 h 5 days 5 days 7 days 7 days 7 days 2 h–6 months 24–72 h 24 h 7 days 24 h 24 h 24 h 24 h

Homes Homes Low energy homes Non-low energy homes Homes Homes Homes Homes Homes Homes Offices (Summer) Offices (Winter) Public buildings Homes Homes Homes New Homes Homes (Summer) Homes Homes (Winter) Homes Homes New Homes

Oxford UK Worldwide (incl. UK and Europe Worldwide (incl. UK and Europe Leipzig, Muchen, Koln Athens Basel Helsinki Milan Prague Europe Europe Europe Europe Europe USA USA Alberta Canada Alberta Japan Japan Japan

[61] [47] [21] [21] [103] [61] [61] [61] [61] [61] [20] [20] [45] [45] [8] [44] [44] [55] [64] [55] [63] [24] [24]

42 47 188 41 46 148 140 179 96 60 1783 206 50 96 50 50 1125 292

< LOD = Below limit of detection. < LOQ = Below limit of quantification.

ATSDR value of 10 μg m−3 is suggested as the long-term health-based guideline value which accounts for the potential for increased susceptibility of children and is protective of carcinogenicity. General VOC levels and particularly formaldehyde in newer housing were amongst the highest in all studies of domestic buildings, emphasising again the need for source control on emissions from building, construction and consumer products and a focus on new and renovated buildings. Given the common presence of formaldehyde above the 1-year HBGV of 10 μg m−3, it is important that a UK indoor air guideline for formaldehyde is established. Studies of naphthalene show mean concentrations are generally below the proposed long-term guideline of 3.0 μg m−3 guideline

suggested except in the case of smoking homes where (e.g. [88] naphthalene concentrations are in the range of (2.8–44.7 μg m−3), Based on analysis using environmental tobacco smoke (ETS) tracers [89], estimated approximately 3% of naphthalene was due to ETS [90]. provide a comparable estimate, with a concentration increase of 0.1–0.2 μgm−3 due to smoking. The source of additional naphthalene in smoking homes is unclear. In the literature the suggested most important and likely indoor sources are the use of naphthalene as pest repellents or deodorisers. However, in the EU the sale of naphthalene containing mothballs has been prohibited since 2008, so the contribution from this source would be expected to decline over time as the use of these mothballs is phased out. Other potential sources include an

Table 3f Formaldehyde (50-00-0) concentrations (μg.m−3) observed in indoor environments. Mean 23.4 22.2 24.0 26.0 34.7 57.8 23.5 17.5 23.2 16.7 8.1 16.0 16.7 21.5 69.0 94.0 26.1 31.0 23.7 86.0 134.0 160.0

Median

19.5 19.4 16.6 21.1

25.4 21.3

Max

Min

135.2 171.0 75.0 80.0 86.0 160.0

2.6 1.0 10.0 11.0 14.4 5.8

86.3

1.3

34.5 23.0 49.0 49.7 57.2 62.2

1.7 1.7 4.7 1.5 3.9 5.8

134.0 110.0 65.0

< LOD* 9.8 1.7

450.0

20.0

SD

9.0 10.0 1.9 6.9 10.5

95th percentile 61.2

46.6 29.9 44.2

99.0 59.0

58.0 93.0 70.0

Study Sample

Monitoring Period

Environment

Location

Source

182 876 32 33 3,601 22,783 61 567 490 82 95 112 148 140 185 97 60 3370 671 4,292 50 50 1125 292 471

3 days 3 days 2 weeks 2 weeks Variable Variable 72 h 7 days 7 days 7 days 7 days 7 days 7 days 7 days 7 days 7 days 7 days 2 h–6 months 24–72 h 8 h–7 days 24 h 24 h 24 h 24 h 20mins/1yr

Homes Homes Homes Living room Homes Main bedroom Low energy homes Non-low energy homes Homes/Apartments Homes/Apartments Homes/Apartments Homes Homes Public buildings Offices (Summer) Offices (Winter) Public buildings Homes Homes and Public Buildings Homes New Homes Homes Homes (Summer) Homes (Winter) Homes New Homes Decorated Homes

UK UK UK UK Worldwide (incl. UK and Europe) Worldwide (incl. UK and Europe) Paris Paris Paris Finland Lithuania Europe Europe Europe Europe Europe Europe USA USA Australia Alberta Alberta Japan Japan Xi'an China

[42] [47] [51] [51] [21] [21] [52] [53] [54] [104] [104] [48] [20] [20] [45] [45] [8] [44] [44] [49] [55] [55] [24] [24] [50]

* < LOD = Below limit of detection. 11

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Table 3g Naphthalene (91-20-3) concentrations (μg.m−3) observed in indoor environments. G Mean 0.3 1.3 < 1.0 1.2 0.29 5.4 1.6 1.45 0.62 0.18-1.7 a

Median

0.9 2.8 1.6 1.1

Max

Min

0.3 2.1 4.9

0.3 0.6

95th percentile

1.2 19.1

44.7 23.0

SD

0.66 28.2

0.41

Study Sample

Monitoring Period

Environment

location

Source

3,601 22,783 555 2790 206 288 150 49 96 50 485

Variable Variable 4 weeks 2 h–6 months 24–72 h 3–7 days 24 h 30–50 min 7 days 5 days 30 min–4 weeks

Low energy homes Non-low energy homes Homes Homes New Homes Homes Smoking Homes Homes/New homes Homes Homes Homes (multiple studies) nonsmoking

Worldwide (incl. UK and Europe) Worldwide (incl. UK and Europe) Germany USA USA USA USA Australia Canada Windsor, Canada Various countries

[21] [21] [75] [44] [44] [91] [88] [105] [64] [56] [92] a

Also showed a range of mean outdoor concentrations between 0.02 and 0.31 μg m−3

maximum concentration of 1784 μg m−3. All past and current studies indicate that all values seen are well below the proposed HBGV. For Trichloroethylene no safe level of exposure can be recommended, because it is a genotoxic carcinogen. The concentrations of airborne trichloroethylene associated with an excess lifetime cancer risk of 1/10 000, 1/100 000 and 1/1 000 000 are 21, 2.1 and 0.21 μg m−3. Mean concentrations seen in case-studies are between values below the limit of detection and up to 6 μg m−3. Indoor sources are unclear, although its use in metal cleaning and degreasing agents is suggested [94]. [8,19,20]; all reported trichloroethylene as present, but that the source was uncertain. In the past, this compound was used in dry-cleaning and is also a breakdown product of tetrachloroethylene. However, without further data, source control of this VOC could be problematic. In the case of Xylene, there are three forms of xylene in which the methyl groups vary on the benzene ring: xylene (m-, o-, and p-xylene) [95]. Following recent health studies (e.g. [93], we have treated these together as a xylene-mixture (CAS no. 1330-20-7). All the studies seen have mean values below the proposed limit of 100 μg.m-3, although three studies [8,21,49], (non-low energy homes), show higher

attached garage, wood stoves, unvented kerosene heaters and outdoor sources. [6,91]). Compared to other VOCs, naphthalene is frequently not measured in many more recent (later than 2000) studies. The reason for this is unclear. Overall, USA-based studies show the widest range of concentrations with levels generally exceeding European studies, which show median concentrations below 0.6 μg m−3 [92]. Generally, measured mean concentrations are below the 3.0 μg m−3 guideline suggested, accept in the case of smoking homes. For styrene, based on the most recent appraisal of evidence by [93]; a long-term value of 850 μg m−3 has been suggested. Studies show concentrations are substantially below this value in all cases. Studies including tetrachloroethylene show values that are generally well below the proposed limit value of 40 μg m−3 seen in Table 6. However, there are several maximum values in both offices and homes that exceed this (e.g. [20,54,55,62]. The causes of these higher values are unclear and requires further investigation. Toluene is one of the most studied pollutants and has multiple emission sources, both outdoors and indoors. However, the latest toxicological information [93], has led to a short-term (8 h) value of 15,000 μg m−3 and a long-term (annual) value of 2,300 μg m−3. The UK BRE study [42,47] showed the highest Table 3h Styrene (100-42-5) concentrations (μg.m−3) observed in indoor environments. G Mean

Median

1.8 9.4 3.1 1.4 1.8 0.7 1.1 30.3 1.0 2.0 1.1 0.8 1.0 0.8 0.2 0.4 5.9 0.7 0.6 2.3 8.0 64.0 a b

Max

Min

30.0 10.9

0.4 0.1

0.6

4.8

0.9

35.1

< LOD

32.0 39.7 12.0 5.6 3.2 22.1

0.0 < LODa < LOQb 0.0 0.0

0.7

14.1

0.1

0.71

40

< LOQ

0.4

SD

95th percentile

2.3

1.5 0.6 1.5 157.4 1.7 1.9

2.7 4.8

4.4

9.0 190.0

Study Sample

Monitoring period

Environment

Location

Source

40 3,601 22,783

24 h variable variable 48 h 48 h 48 h 48 h 7 days 7 days 48 h 4 weeks 4 weeks 5 days 5 days 7 days 7 days 2 hours-6 months 7 days 5 days 24 h 24 h 24 h

Oxford Worldwide (incl. UK and Europe) Worldwide (incl. UK and Europe) Worldwide (incl. UK and Europe) Leipzig München Koln Athens Basel Helsinki Milan Paris Paris Prague Germany Leipzig Europe Europe Europe Europe USA Canada Windsor, Canada Japan Japan Japan

[61] [21] [21]

2103 42 47 188 41 567 490 46 555 2,242 148 140 128 88 6149 86 50 49 1125 292

Homes Low energy homes Non-low energy homes Homes Homes Homes Homes Homes Homes/Apartments Homes/Apartments Homes Homes Homes/Apartments Offices (Summer) Offices (Winter) Public buildings Homes New Homes Homes Homes Homes Homes New Homes

< LOD = Below limit of detection. LOQ = Below limit of quantification.

12

[103] [61] [61] [61] [61] [53] [54] [61] [75] [62] [20] [20] [45] [45] [44] [64] [69] [63] [24] [24]

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Table 3i Tetrachloroethylene (127-18-4) concentrations (μg.m−3) observed in indoor environments. G Mean 0.4 1.7 0.4 < LODa 8.2 2.9 0.7 0.9 2.0 (1.1–2.8) 4.0 1.4 0.8 0.6 2.5 3.0 7.0 0.2 0.4 a

Median

Max

Min

0.7 2.5

0.1 1.4

72.1 45.4 1.0 290.0

< LOD 0.0 < LODa < LODa

< LOD -2.2 0.7

179.3

0.1

0.3 0.4

721.0 31.0

0.0 0.1

1.4 1.3 0.3

SD

95th percentile

7.3 1.1 17.0 3.6

a

2.3 0.2 9.0 12.0

Study Sample

Monitoring Period

Environment

Location

Source

3,601 22,783 567 490 2,242 148 140 3429 206 15 Studies 96 3857 50 50 107 128 10 studies 1125 292 602 602

7 days 7 days 7 days 7 days 4 weeks 5 days 5 days 2–6 months 24–72 h Various 7 days 7 days 24 h 24 h 3h 24 h 7 days 24 h 24 h 24 h 24 h

Low energy homes Non-low energy homes Homes/Apartments Homes/Apartments Homes/Apartments Offices (Summer) Offices (Winter) Homes New Homes Homes Homes Homes-National Survey Homes (Summer) Homes (Winter) Homes Homes Homes Homes New Homes Homes (Summer) Homes (Winter)

Worldwide (incl. UK and Europe) Worldwide (incl. UK and Europe) Paris Paris Leipzig Europe Europe USA USA USA Canada Canada Alberta Alberta Korea Shanghai China Japan Japan Japan Japan

[21] [21] [53] [54] [62] [20] [20] [44] [44] [106] [64] [78] [55] [55] [25] [107] [108] [24] [24] [80] [80]

< LOD = Below limit of detection.

The ADF, 2010 guideline concentration value of 300 μg m−3 was derived based on evidence collated in the European Collaborative Action report [96]. It used two approaches to arrive at this figure: 1) the toxicological responses published in indoor air pollution literature of the time, which in the 27 years proceeding this report has advanced substantially as we have shown and 2) analysis based on gas chromatographic separation and quantification (as used in ISO 16000-6:2011). Species were ranked based on the then current data and divided into the following classes: alkanes (100 μg m−3), aromatics (50 μg m−3), terpenes (30 μg m−3), halocarbons (30 μg m−3), esters (20 μg m−3), carbonyls (excluding formaldehyde) (20μ g.m−3), and “other” (50 μg m−3). Formaldehyde as a VVOC is not included in these figures, as it uses a different measurement method to ISO 16000-6:2011. It is also stated that ‘and no individual compound should exceed 50% of its class target or 10% of the TVOC target guideline value. These target guideline values are not based on toxicological considerations, but on existing levels and on a professional judgment about the achievable levels’ [96]. See also [34]. This review proposes health-based guidance values for specific VOCs based on the assessment of current evaluations by authoritative bodies, rather than the use of a TVOC guideline. The specific VOCs comprise α-pinene, D-limonene, naphthalene, styrene, tetrachloroethylene, toluene, and xylenes (mixture). In addition, and due to its carcinogenic nature at high concentrations, formaldehyde is also recommended for inclusion along with acetaldehyde. These compounds should be measured using the qualitative analysis previously discussed under ISO 16000 and rigorous experimental methodologies as suggested by [8]. Health-based guidance values have not been proposed for the genotoxic carcinogens benzene and trichloroethylene because there is no safe level of exposure to these compounds. Overall, we suggest that, based on our study and current knowledge, individual health-based guidance values for individual VOCs are a more appropriate way forward, with TVOC being used as an indicator of indoor air quality. We are aware that new compounds are emerging, and we do not always measure the same compounds. Hence, VOC scanning during field studies is useful to identify new tendencies.

maximum concentrations. 4.2. TVOC as a performance criterion As previously stated, few studies considered measurements of TVOC concentrations. Many focussed on specific VOCs in their investigations. Additionally, although some studies looked at a wide range of VOCs, they were analysed independently and not correlated with each other in the individual buildings investigated. In general terms, concentrations of VOCs seen in offices are lower than those seen in homes, which may be affected by ventilation strategies, different cleaning activities, envelope permeability and/or room geometry. Some studies that investigated TVOCs, (e.g. [21,42] show mean values exceeding the current UK limit value of 300 μg m−3 (ADF, 2010). It is suggested that many of the major monitoring/field studies examining VOCs may possibly indicate TVOC concentrations above the ADF, 2010 figure for some buildings, based on individual pollutants measured and postulating the likely occurrence of other commonly seen compounds. However, this may not be the case and it is also important to note that overall concentrations are likely to reduce with time. All the monitoring/field studies reviewed have been carried out post-occupancy and therefore include VOCs from consumer products, such as cleaning, polishing, personal care products and furniture, whose use depend on our personal behaviour, in addition to those from construction materials, fixtures and fittings and external sources. It is felt that post-occupancy monitoring represents a more realistic appraisal of total indoor VOC exposure from all sources. We suggest a gradual move towards operational performance where ‘occupied’ rather than simply ‘design and as-built’ submissions for compliance with ADF, 2010 could occur. Additionally, TVOC alone reveals nothing regarding the nature of the individual VOCs that comprise it, their concentrations and possible toxicity to humans. There are limitations to TVOCs usage as a measure other than giving an indication of insufficient ventilation (air change) rate [33]. Any assumption that all VOCs within the TVOCs measured have the same health endpoint and can be added together cannot be supported from a toxicological standpoint, as TVOC summarises the presence of compounds of very different toxicity [35]. Under the current Post Completion Compliance Test (PCCT), a high TVOC concentration (above the current 300 μg m−3) is at best indicative of poor IAQ and low ventilation rates, while a lower value may still result in health effects.

4.3. Possible mitigation strategies for VOC in new dwellings It has been suggested that increasing ventilation rates for buildings (above ADF, 2010) for a period pre- or post-occupancy, when VOC emissions are likely to be at their highest, would assist in reducing 13

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Table 3j Toluene (108-88-3) concentrations (μg.m−3) observed in indoor environments. G Mean

Median

23.7 15.1 17.5 16.4 41.1 0.8 20.0 74.0 15.0 13.6 82.7 19.5 20.1 77.6 86.2 37.3 20.5 8.1 6.1 4.4 11.7 15.0 20.0 26.5 17.8 (14.1–21.5) 9.9 18.3 14.3 45.2

12.2 0.4

Max

Min

1783.5

0.3

45.2

5.7

260.0

7.5

39.7

0.0

87.0 2400.0

63.0 62.0 63.7 160.6 163.5

< LODb < LOD 0.5 1.3

24.7

436.3

3.8

6.1 7.6

82.0 383.0 240.0

6.1 0.4 < LOD

2.6–10.1

a b

14.0

50.0

41.5 24.8

< LOQa

95th percentile 74.9

82.9

Study Sample

Monitoring Period

Environment

Location

Source

40 876 155 3,601

24 h 4 weeks 12 h Various

Homes Homes Homes Low energy homes

[61] [47] [58] [21]

22,783

Various

Non-low energy homes

567 2,242 L/scale L/scale 44 555 42 47 188 41 46 204 201 148 140 186 96 60 6617 666 96 3857 50 50 919

Homes/Apartments Homes/Apartments Homes Homes Homes Homes Homes Homes Homes Homes Homes Homes Homes Offices (Summer) Offices (Winter) Public buildings Homes Homes Homes New Homes Homes Homes-National Survey Homes (Summer) Homes (Winter) Homes

Oxford UK UK Worldwide (incl. UK and Europe) Worldwide (incl. UK and Europe) Paris Leipzig Helsinki Helsinki Germany Germany Athens Basel Helsinki Milan Prague Erfurt Hamburg Europe Europe Europe Europe Europe USA USA Canada Canada Alberta Alberta Australia Perth Beijing

[77] [79]

Beijing

[79]

Korea Japan Japan Japan Japan Japan

[25] [63] [24] [24] [80] [80]

24.7

387 152

7 days 4 weeks 7 days 7 days 4 weeks 4 weeks 48 h 48 h 48 h 48 h 48 h 7 days 7 days 5 days 5 days 7 days 7 days 7 days 2–6 months 24–72 h 7 days 7 days 24 h 24 h 8h – 7 days 24 h 1h

13.2

255

1h

112.0

107 50 292 1125 602 602

3h 24 h 24 h 24 h 24 h 24 h

1.9

141.0 13.2 24.4 70.1 95.7

26.4 184.0 16.0 27.0 15.0 10.8 12.2

SD

57.6

95.0 45.0

56.0 35.0

Homes Homes renovated within 5 years Homes renovated over 5 years ago New Apartments Homes New Homes Homes Homes (winter) Homes (summer)

[21] [53] [62] [28] [28] [74] [75] [61] [61] [61] [61] [61] [76] [76] [20] [20] [45] [45] [8] [44] [44] [64] [78] [55] [55] [49]

LOQ = Below limit of quantification. < LOD = Below limit of detection.

occupant exposure [21]. Other authors have suggested the use of ‘bakeout’ procedures in conjunction with increased (forced) ventilation rates [97], where for a period up to a week (preferably pre-occupation), indoor temperatures are raised (varying between 30 and 40 °C) to reduce the high level off-gassing phase [26,98,99]. Holøs et al.[26] carried out a review and meta-analysis of the influence of ventilation and bake-out and showed that the off-gassing phase of new or recently ventilated buildings follows a multi-exponential trend in terms of VOC decay, with a rapid decline in emissions during the first month (for some species) followed by a more gradual decrease, until a steady state is reached after at least two years and from some studies longer. This method has several draw backs, namely increases in ventilation, heat losses, increased CO2 emissions during the period and the additional cost of space heating, all of which could mitigate against other government policy goals, e.g. reducing end-use energy demand, fuel poverty and greenhouse gas (GHG) emissions. Photocatalytic oxidation (PCO), is an emerging technology aiming to remove VOCs from indoor air. Research has highlighted several issues that need to be resolved before this can be considered viable including: the generation of harmful intermediates, moderate performance and the unknown durability of photocatalysts [100,101] with source control still the preferable option.

In the current version of ADF (2010), which is under review, it is stated that there is ‘limited knowledge about the emission of pollutants from construction and consumer products used in buildings and the lack of suitable schemes for England and Wales’. There have been several voluntary emission labelling schemes available for indoor construction materials and fixtures and fittings for some time in Europe [35,71], which the EU are in the process of harmonising to give one clear standard. As the UK currently has no VOC labelling scheme for construction or consumer products (excluding paints), these standards (and the source information seen in Table 2) may help inform the initiative of the UK Government to investigate voluntary VOC labelling schemes suggested in the Clean Air Strategy, 2019 [102]. 4.4. Optimal strategies Although the focus of this study is on VOCs, these are only one of a range of indoor-sourced airborne pollutants to which occupants are exposed including: particulate matter (PM), nitrogen dioxide (NO2), carbon monoxide (CO), tobacco smoke and radon as well as mould and allergens. It is acknowledged that any strategy for good IAQ must also include all pollutants encountered in the indoor air, from both indoor 14

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Table 3k Trichloroethylene (971-01-06) concentrations (μg.m−3) observed in indoor environments. G Mean

Median

Max

Min

3.0

6.0

1.5 1.0 0.1

0.2 < 1.0

0.5

a

< LOD < LOQb 2.3 6.0 0.4 0.23 0.9 0.6 0.3 (0.3–0.4)

< LODa-1.2 0.4 0.14 0.1

Study Sample

Monitoring Period

Environment

Location

Source

0.2

3,601

Various

Low energy homes

[21]

3.0

0.3

22,783

Various

Non-low energy homes

16.22 11.3 4087.2 0.8 1.8

0.0

4.7 3.6 1.7

0.41 0.0 0.0

567 2,242 555 490 148 140 5569 460 15 Studies 93 50 50 50 3857

7 days 4 weeks 4 weeks 7 days 5 days 5 days 2–6 months 24–72 h Various 7 days 24 h 24 h 24 h 7 days

107 128 10 studies 602 602

3h 24 h 7 days 24 h 24 h

Homes/Apartments Homes/Apartments Homes Homes/Apartments Offices (Summer) Offices (Winter) Homes New Homes Homes Homes Homes (Summer) Homes (Winter) Homes Homes-National Survey Homes Homes Homes Homes (Summer) Homes (Winter)

Worldwide (incl. UK and Europe) Worldwide (incl. UK and Europe) Paris Leipzig Germany Paris Europe Europe USA USA USA Canada Alberta Alberta Winsor, Canada Canada Korea Shanghai China Japan Japan

[25] [107] [108] [80] [80]

b

0.5

< LODa < LODa < LODa

< 1.1 0.8 1.8 0.0 0.1 a

SD

95th percentile

7.3 < 1.0

3.9

< 1.1 0.2

[21] [53] [62] [75] [54] [20] [20] [44] [44] [106] [64] [55] [55] [55] [78]

< LOD = below limit of detection. < LOQ = Below limit of quantification.

and outdoor sources, considering possible interactions between different species, meaning that optimal strategies are needed.

proposed both short and long-term health-based guidance values. We would like to emphasise that it is the first time in the UK that IAQ guidelines are proposed for selected VOCs. As there is the potential for new compounds to emerge a VOC scan during field studies is an important method for identifying these, and the trends and tendencies of when they arise. Although some mitigation approaches have been suggested, source control is still considered the primary strategy for improving IAQ and the most effective method of reducing indoor general population exposure, with any residual concentrations dissipated by good ventilation practices. Labelling schemes for construction products, fixtures and fittings together with consumer products that may be introduced as discussed in the Clean Air Strategy, 2019 [102], could follow the European example to trigger change and innovation in the marketplace.

5. Conclusions and recommendations Addressing the effects of indoor air pollution in buildings and its impact on occupant health has become an increasingly important focus area for government and industry. This paper has investigated the need to consider specific VOCs rather than only a TVOC guideline. It establishes that recent scientific data and toxicological evaluations highlight specific VOCs with health impacts at relatively low concentrations, and cross references these with concentrations seen in large-scale monitoring studies both in the UK and internationally. These include acetaldehyde, α-pinene, D-limonene, formaldehyde, naphthalene, styrene, tetrachloroethylene, toluene, and xylenes (mixture), for which we

Table 3l Xylenes (mixture) (1330-20-7) concentrations (μg.m−3) observed in indoor environments. G Mean 12.5 8.1 35.5 9.8 30.4 10.2 10.1 88.2 22.2 4,8 3.8 3.3 8.4 5.6 9.7 9.9 7.5 a

Median

Max

Min

4.6

14.0 190.0 58.6

1.8 3.1

9.9

SD 21.7

14.6 8.2 7.5 184.1 12.2

248.0 40.0 20.0 97.3 48.1 177.4

< LODa < LODa 0.9 0.7

77.1 320.0

1.6 < LOD

95th percentile

21.2

Study Sample

Monitoring Period

Environment

Location

Source

40 3,601 22,783 2103 42 47 188 41 46 555 148 140 186 96 60 500 96 1,177

24 h Various Various 4 weeks 48 h 48 h 48 h 48 h 48 h 4 weeks 5 days 5 days 7 days 7 days 7 days 2–6 months 7 days 8 h–7 days

Homes Low energy homes Non-low energy homes Homes Homes Homes Homes Homes Homes Homes Offices (Summer) Offices (Winter) Public buildings Homes Homes Homes Homes Homes

Oxford Worldwide (incl. UK and Europe) Worldwide (incl. UK and Europe) Leipzig. Muchen. Koln Athens Basel Helsinki Milan Prague Germany Europe Europe Europe Europe Europe USA Canada Australia

[61] [21] [21] [103] [61] [61] [61] [61] [61] [75] [20] [20] [45] [45] [8] [44] [64] [49]

< LOD = below limit of detection. 15

cancer, respiratory, cardiovascular renal

Homes

600 ST4 -

-

-

90 ST3 -

Toxicological Endpoints

Applicable to Name (CAS no.)

TVOCd Acetaldehyde (75-07-0)

Acrolein (107-02-8)

α-Pinene (80-56-8)

Benzaldehyde (100-52-7) Benzene (71-43-2) Benzo(a)pyrene (50-32-08) Chloroform (67-66-3) D-Limonene (5989-27-5)

16

-

-

[109]

cancer, respiratory, cardiovascular renal effects

Homes

n-Hexane (100-54-3) Propionaldehyde (12338-6) Styrene (100-42-5)

Location

Toxicological Endpoints

Applicable to Name (CAS no.)

Naphthalene (91-20-3)

120 ST3 80 LT2 -

Ethylbenzene (100-41-4) Formaldehydef (50-00-0)

-

[109]

Location

Homes

cancer, respiratory effects

[110]

-

-

3800 LT3 100 ST2

-

-

-

-

400 ST4 48 LT3

Homes

cancer, respiratory

[110]

Offices and public buildings

cancer, renal and neurological effects

[111]

-

-

-

30-100 ST4

-

16.1 ST4 -

-

-

2-600 ST4 -

Offices and public buildings

cancer, renal and neurological

[111]

Homes

respiratory, cardiovascular and neurological effects

[112]

40(7Days)

-

100 ST2 60 LT2 -

-

2.5 LT3 -

-

-

100 ST3

Homes

respiratory, cardiovascular and neurological

[112]

General population indoor exposure

respiratory, cardiovascular and neurological effects

[6]

-

-

100 ST2, LT3 10 LT3

-

(0) 0.17e 0.012e

-

-

-

General population indoor exposure

respiratory, cardiovascular and neurological

[6]

Public buildings

cancer, respiratory effects

[113]

-

-

-

100 ST2-4

-

5 LT3 -

-

-

400 ST4 -

Public buildings

cancer, respir-atory

[113]

Table 4 Various National and International health-based guidance values (HBGVs) for inhalation for VOCs in μg.m−3.

Commercial and service buildings

respiratory, and other end points

[114]

260 ST4

-

-

100 ST4

-

5 ST4 -

-

-

600 ST4 -

Commercial and service buildings

respiratory and other end points

[114]

Homes

cancer noncancer end points

[115]

-

-

10 > LT3

1500 ST3 100 ST2

450 LT3

0.2LT3 -

450 LT3

0.8 > LT3

300 ST3 160 > LT3

Homes

cancer, noncancer end points

[115]

Homes

cancer first, respiratory and other end points

[116]

900 > LT3

-

9 ST4, LT3 55 ST3 9 > LT3

-

3 LT3 0.002 > LT3

140 > LT3 300 ST4 470 ST3 0.35 > LT3 0.7 ST4 2.5 ST3 -

Homes

cancer first, respiratory and other end points

[116]

a

Homes

respiratory, cardiovascular, renal and neurological effects

[117]

850 LT

8 LT

2000 LT 50 LT1 123 ST3 10 LT1

300 LT -

0 LT -

-

0.35 LT

2-500 ST4 280LT2 1420 ST3

Homes

respiratory, cardio vascular, renal and neurological

[117]

b

c

Low energy Homes and public buildings

respiratory, cardio-vascular and neurological effects

[119]

220 LT3

3 TL 31 IL -

100 TL

-

0.4 IL -

-

-

300 TL 160 TL 480 IL

Low energy Homes and public buildings

respiratory, cardio-vascular and neurological

[119]

(continued on next page)

Homes, public buildings and means of transport

cancer first, respiratory and other end points

[118]

30 RWI 300 RWI

10 RWI 30 RWII -

200 RWI 200 RWI 2000 RWII 200 RWI 100 RWI

200 RWI 2000 RWII 20 RWI -

-

300 RWI 100 RWI 1000 RWII

Homes, public buildings and means of transport

cancer first, respiratory and other end points

[118]

C. Shrubsole, et al.

Building and Environment 165 (2019) 106382

-

-

870 LT3

Homes

200 ST3

-

-

-

Applicable to Name (CAS no.)

Toluene (108-88-3)

Trichloroethylene (71-0106) Tetrachloroethylene (12718-4) Xylenes (1330-20-7) 1447 ST4

-

-

1092 ST4

Offices and public buildings

cancer, renal and neurological

[111]

350 ST4

-

-

75 ST3

Homes

respiratory, cardiovascular and neurological

[112]

-

250 LT3

2.3e

General population indoor exposure

respiratory, cardiovascular and neurological

[6]

-

-

-

-

Public buildings

cancer, respir-atory

[113]

-

250 ST4

25 ST4

250 ST4

Commercial and service buildings

respiratory and other end points

[114]

200 LT3

250 LT3

2 LT2

1900 ST3

Homes

cancer, noncancer end points

[115]

700 LT3 22000 ST3

-

300 LT3 37000 ST3 0.2 LT3

Homes

cancer first, respiratory and other end points

[116]

17

ST2 = 30 min LT2 = 24 h

ST3 = 1 h LT3 = Annual

ST4 = 8 h

a

100 LT

40 LT

2300 LT3 15000 ST4 -

Homes

respiratory, cardio vascular, renal and neurological

[117]

b

100 RWI 1000 RWII 100 RWI 800 RWII

300 RWI 3000 RWII -

Homes, public buildings and means of transport

cancer first, respiratory and other end points

[118]

c

4 TL 38 IL -

4000 TL 5000 IL 0.2 TL 2.5 IL

Low energy Homes and public buildings

respiratory, cardio-vascular and neurological

[119]

a Canada uses screening values for some species - Indoor Air Reference Levels (IARL). These are used to access possible risk. They are associated with acceptable levels of risk after long-term exposure (over several months or years) for each specific VOC. Due to uncertainties in derivation, these have simply been labelled ‘long term’ (LT). b Germany uses the guide values RWI and RWII. RWI represents the concentration of a substance in indoor air for which, when considered individually, there is no evidence at present that even life-long exposure is expected to bear any adverse health impacts. RWII is an effect-related value based on current toxicological and epidemiological knowledge of a substance's effect threshold that takes uncertainty factors into account. It represents the concentration of a substance which, if reached or exceeded, requires immediate action as this concentration could pose a health hazard, especially for sensitive people who reside in these spaces over long periods of time. Depending on how the substance concerned works, RWII may be defined either as a short-term value (RW II K) or a long-term value (RW II L). c The Flemish Government uses the terms target level (TL) and intervention level (IL), which are interpreted as long-term and short-term values respectively. d TVOC is not based on toxicological information, but it is generally set to be as low as reasonably achievable as the result of investigations on indoor VOC concentrations. e Concentrations associated with an excess lifetime risk of 1/1,000,000. f Formaldehyde is strictly a VVOC, but generally present in relatively high concentrations in the indoor environment.

ST1 = 15 min LT1 = 8 h

Definitions: ST = short term exposure, LT = long term exposure. In some cases, an 8-h exposure limit is referred to as to as a short term and/or long-term exposure.

260 LT3

Homes

cancer, respiratory

cancer, respiratory, cardiovascular renal

Toxicological Endpoints

[110]

[109]

Location

Table 4 (continued)

C. Shrubsole, et al.

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Table 5 Indoor exposure limits in building design certifications and independent research projects (μg.m−3). Standard

IEA-EBC Annex 68 [21]

Europe Index project [28]

Europe EPHECT Project 2015 [18]

WELLv2a

LEEDv4

ASHRAE 189.1

Applicable to

Low energy homes and public buildings

Homes

Critical Exposure Limit (CEL) Homes

Ventilation/material emission-based Offices and public buildings

Ventilation/material emission based All building types

Ventilation only Green buildings nonresidential

TVOC Acetaldehyde

600 ST4 48 LT3 4600 ST3 0.35 LT3 6.9 ST4 200 LT2

200 LT3

-

-

500 ST4 140 ST4

140 ST4

-

-

-

-

-

-

-

0.2 LT2 150 LT1 300 ST3 -

0 -

10 LT2 21 ST3 4,500 LT2 45,000 ST3 -

30 LT3 150 LT3

3 ST4 2000 ST4

60 ST4 2000 ST4

-

-

-

1000 LT3

7000 ST4

7000 ST4

33 LT3

100 ST4

3500 LT3 17.5 LT3

9 ST4, LT3 55 ST4 9 ST4 7000 ST4 600 ST4

150 LT3

300 ST4

300 ST4

Acrolein α-Pinene Benzaldehyde Benzene Benzo(a)pyrene Chloroform D-Limonene

Ethylbenzene Formaldehyde Naphthalene n-Hexane Propionaldehyde Tetrachloroethylene Toluene

-

-

0 LT 3800 ST 9 LT2 123 ST3 2 LT3 100 LT2 1380 ST3 250 LT2-3

9,000 LT2 90,000 ST3 -

1 LT3 10 LT3 -

100 ST2, LT2 10 LT2 -

300 LT3

−3

Indoor Air Guidelines for VOCs proposed by various organisations and research projects (μg.m

9 ST4 7000 ST4 600 ST4

)

Location

IEA-EBC Annex 68 [21]

Europe Index project [28]

Europe EPHECT Project 2015 [18]

WELLv2

LEEDv4

ASHRAE 189.1

Applicable to

Low energy homes and public buildings

Homes

Homes

Offices and public buildings

All building types

Green buildings non-residential

Trichloroethylene Xylenes

2 ST3, LT2 200 LT2 22000 ST2 30 LT3 2100 ST2

200 LT3

-

300 LT3 350 LT3

35 ST4 700 ST4

35 ST4 700 ST4

250 LT3

-

-

900 ST4

900 ST4

Styrene

Definitions: ST = short term exposure, LT = long term exposure. In some cases, an 8-h exposure limit is referred to as to as a short term and/or long-term exposure. ST1 = 15 min LT1 = 8 h

ST2 = 30 min LT2 = 24 h

ST3 = 1 h LT3 = Annual

ST4 = 8 h

a For the Well standard, data is analysed and compared to the limit value for regularly occupied hours only. The standards quoted exclude commercial kitchen spaces.

18

19

100 (30min)

-

-

Naphthalene (91-20-3)

Styrene (100-42-5)

90,000 (30min)

Formaldehyde (50-00-0)

D-Limonene

(5989-27-5)

[93]

[121]; USA

3.0+ (1yr) 850 (1y)∧

[6]. ATSDR MRL (1999)

EPHECT [18]

[6]

EPHECT [18]

Source Document [93] a

10 (1yr)

9000 (1 day)

No safe level of exposure can be recommended. The unit risk of leukaemia per 1 μg m−3 air concentration is 6 × 10−6. The concentrations of airborne benzene associated with an excess lifetime cancer risk of 1/10 000, 1/100 000 and 1/1 000 000 are 17, 1.7 and 0.17 μg m−3, respectively.

Benzene* (71-43-2)

4500 (1 day)

45,000 (30min)

α-Pinene (80-56-8)

Long Term 280 (1day)

Acetaldehyde (75-07-0)

VOCs

Limit Values in μg.m−3 Short Term 1,420 (1 h)

Table 6 Health-based indoor air quality guidelines for selected VOCs.

Critical Exposure limit (CEL) inhalation exposure to key and emerging indoor air pollutants emitted during household use of selected consumer products World Health Organisation guidelines valid for short term exposure. ATSDR value of 10 μg/m3 suggested as the long-term health-based guideline value which accounts for the potential for child susceptibility. Value also selected by the [119] There is no proposed guideline for short term exposure due to the lack of scientific evidence. Most recent appraisal of evidence

The risk estimates are based on human health risk. However, it is noted that the current Defra national air quality objectives for benzene for England and Wales is an annual mean of 5 μg m−3, based on the European (EU) ambient air quality directive 2008/50/EC [82,83].

Critical Exposure limit (CEL) inhalation exposure to key and emerging indoor air pollutants emitted during household use of selected consumer products

Most recent appraisal of evidence

Reasoning for choice

(continued on next page)

Sensory irritation of the eyes, nose and throat, together with exposure-dependent discomfort, lachrymation, sneezing, coughing, nausea and dyspnoea. Human carcinogen -longterm exposure linked to nasal cancer.1 Haemolytic anaemia in humans at high doses. Respiratory tract lesions including carcinogenicity reported in long-term animal studies. a,c Sensory irritation of the eyes, nose and throat. High concentrations- headache, nausea, vomiting, weakness, tiredness, dizziness, mild irritation to skin. Long-term exposure has been reported to cause neurological effects in humans including changes in hearing, balance, colour vision and psychological performance.

Irritation of the eyes, skin, and respiratory tract following acute exposure.c Long-term animal studies have reported carcinogenicity and inflammation and injury to tissues of the upper respiratory tract [93] With the exception of its irritative (skin, eyes) and sensitizing properties, it is a chemical with fairly low acute toxicity.d Ozone initiated reactions with terpenes produce gaseous and aerosol phase products, causing sensory irritation of upper airways and airflow limitation. The International Agency for Research on Cancer has classified benzene as carcinogenic to humans (Group 1). Benzene causes acute myeloid leukaemia in adults. Positive associations have been observed for non-Hodgkin lymphoma, chronic lymphoid leukaemia, multiple myeloma, chronic myeloid leukaemia, acute myeloid leukaemia in children and cancer of the lung [120]. As for α-Pinene above

Potential Health impacts

C. Shrubsole, et al.

Building and Environment 165 (2019) 106382

20

[93]

[6]

[93]

[93,106]

Most recently derived and most precautionary value.

This value is based on human data for kidney cancer, which has also been adjusted for other cancers.

Most recent appraisal of evidence, specifically the dose response relationship.

Most recent appraisals of evidence

Irritation to the nose, throat and lungs. Severe inhalation exposure can cause dizziness, headache, confusion, heart problems, liver and kidney damage and comab

Effects in the kidney indicative of early renal disease and neurotoxicity (visual and autonomic disturbances)a,c Evidence of carcinogenicity in animals. Limited evidence for carcinogenicity in humans (positive associations have been observed for bladder cancer) Eye, nose and throat irritation, headaches, dizziness and feelings of intoxication following short-term exposure. Neurological effects including reduced scores in tests of shortterm memory, attention and concentration following longterm exposureb The International Agency for Research on Cancer has classified trichloroethylene as carcinogenic to humans (Group 1). Trichloroethylene causes cancer of the kidney. A positive association observed for non-Hodgkin lymphoma and liver cancer. It is assumed that trichloroethylene is genotoxic [122]

References to ATSDR refer to the date of particular documents dealing with the VOCs concerned. These can be located vis the main portal, shown in the reference list [121]. *No safe level of exposure can be recommended. The concentrations shown are associated with an excess lifetime risk of 1/1,000,000 and are applicable to both long and short-term exposures. +We are aware of new data that indicates that effects may occur at lower doses; however, this new data has not yet been evaluated by an authoritative body. ∧ Health Canada uses screening values for some species - Indoor Air Reference Levels (IARL). These are used to assess possible risk. They are associated with acceptable levels of risk after long-term exposure (over several months or years) for each specific VOC. Due to uncertainties in derivation; these have simply been labelled as annual. In these cases, no separate short-term exposure limit has been stated. Main References. a World Health Organisation. WHO Guidelines for selected pollutants. b Public Health England. Chemical hazards compendium. c United States Environment Protection Agency. Iris Assessments. d [4].

Xylenes-mixture (1330-207)

No safe level of exposure can be recommended. Based on continuous exposure to 1 μg.m-3 from birth to age 70 the estimated lifetime unit risk of kidney cancer (adjusted for other cancers) is 4.8 x 10-6. The concentrations of airborne trichloroethylene associated with an excess lifetime cancer risk of 1/10 000, 1/100 000 and 1/1 000 000 are 21, 2.1 and 0.21 μg.m3, respectively. respectively. 100 (1y)∧

Trichloroethylene* (71-0106)

2,300 (1 day average)

15,000 (8 h)

Toluene (108-88-3)

40 (1day)

-

Tetrachloroethylene (12718-4)

Table 6 (continued)

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Further analytical work is needed to investigate how the effect of using low-emission construction and building materials, furnishing and consumer products impacts VOC concentrations in buildings and any potential changes in health impacts. Additionally, systematic reviews are needed to separate the impacts of building materials from consumer products on indoor VOC concentrations, to create suitable strategies for possible product labelling schemes. VOCs are subject to reactions with other species, as such research to suggest optimal strategies considering all indoor pollutants present are needed. However, the evidence comes down to the need for individual health-based guideline values for specific VOCs rather than a TVOC limit value.

23. 24. 25. 26. 27. 28. 29.

Acknowledgements The authors would like to thank the authors of the many publications quoted, who supplied their base data for analysis and answered our many questions; in particular Louis Cony Renaud Salis of the University of La Rochelle [email protected] for help and assistance given. This research is funded by Public Health England. Appendix A. Literature search: Volatile organic compounds in indoor airSearch Strategies. References from Ovid Embase, Scopus, including citation reports, Elsevier, Google Scholar, PubMed were down loaded into an Endnote database (A). A separate Endnote database (B) was created with the references from EBSCO Global Health TRIP and NICE Evidence, due to the differing search methods allowed by these data bases. We combined the two Endnote Databases A and B, duplicates were removed, and the remainder pasted into a final Endnote database (C). This database contains the unique references (6603) from the sources listed. On the advice of colleagues at PHE, further studies, monitoring studies and national guidelines were located via other sources (98) which were added making a total of 6,701 documents (See Fig. 1 in the main text). There are slight variations in the strategy for the different databases due to differences in the framework of investigation permitted. Search Strings.

•

• Ovid Embase, Scopus, including citation reports, Elsevier, Google Scholar, PubMed 1. volatile organic compound*.tw,kw. 2. (VOC or VOCs).tw,kw. 3. aromatic.tw,kw. 4. (semi-volatile organic compound* or semivolatile organic compound*).tw,kw. 5. (SVOC or SVOCs).tw,kw. 6. benzene.tw,kw. 7. formaldehyde.tw,kw. 8. toluene.tw,kw. 9. styrene.tw,kw. 10. volatile organic compound/ 11. aromatic compound/ 12. benzene/ 13. formaldehyde/ 14. toluene/ 15. styrene/ 16. 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11 or 12 or 13 or 14 or 15 17. indoor*.tw,kw. 18. office*.tw,kw. 19. (home or homes or dwelling*).tw,kw. 20. domestic.tw,kw. 21. new building*.tw,kw. 22. green building*.tw,kw.

•

low carbon.tw,kw. indoor air pollution/ ambient air/ workroom air/or microclimate/ home environment/ sick building syndrome/ 17 or 18 or 19 or 20 or 21 or 22 or 23 or 24 or 25 or 26 or 27 or 28 30. (source or sources).tw,kw. 31. emission*.tw,kw. 32. building material*.tw,kw. 33. furnishing*.tw,kw. 34. decoration.tw,kw. 35. paint.tw,kw. 36. fixtures.tw,kw. 37. renovation*.tw,kw. 38. ventilation.tw,kw. 39. energy efficien*.tw,kw. 40. airtight*.tw,kw. 41. air permeabil*.tw,kw. 42. decay rate*.tw,kw. 43. building material/ 44. paint/ 45. air conditioning/ 46. 30 or 31 or 32 or 33 or 34 or 35 or 36 or 37 or 38 or 39 or 40 or 41 or 42 or 43 or 44 or 45 47. 16 and 29 and 46 48. limit 47 to yr = "2000–2018″ 49. limit 48 to English language EBSCO Global Health 1. S13 S4 AND S7 AND S12 2. S12 S8 OR S9 OR S10 OR S11 3. S11 TX “decay rate*" 4. S10 (DE “Paint”) OR (DE “ventilation” OR DE “artificial ventilation” OR DE “natural ventilation") 5. S9 DE “building materials” OR DE “blockboard” OR DE “bricks” OR DE “cement” OR DE “composite boards” OR DE “concrete” OR DE “ferrocement” OR DE “fibreboards” OR DE “mortar” OR DE “mud” OR DE “particleboards” OR DE “plasterboard” OR DE “shingles” OR DE “slabs” OR DE “slates” OR DE “strawboards” OR DE “thatch” OR DE “tiles” OR DE “timbers” OR DE “wallboard" 6. S8 TX Sources OR Emissions OR “Building materials” OR Furnishing* OR Decoration* OR Renovation* OR Paint OR Fixtures OR Ventilation OR “Energy Efficien*” OR Airtight* OR “Air Permeabil*" 7. S7 S5 OR S6 8. S6 DE “homes" 9. S5 TX Indoor* OR Office* OR home OR homes OR domestic OR “New Building*” OR “Green Building*” OR “Low Carbon” 10. S4 S1 OR S2 OR S3 11. S3 DE “aromatic compounds" 12. S2 (((DE “benzene”) OR (DE “formaldehyde")) OR (DE “toluene")) OR (DE “styrene") 13. S1 TX “Volatile organic compounds” OR VOC OR VOCs OR Aromatic OR semivolatile organic compound*OR semivolatile organic compound*semivolatile organic compound*semivolatile organic compound* OR semi-volatile organic compound* OR SVOC OR SVOCs OR Benzene OR Formaldehyde OR Toluene OR Styrene TRIP, NICE Evidence volatile organic compounds, indoor air.

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