Indoor air quality in the university libraries of Modena (Italy)

ELSEVIER

The Scienceof the Total Environment 193 (1996) 49-56

Indoor air quality in the university libraries of Modena (Italy) Guglielmina Fantuzzi+* , Gabriella Aggazzotti”, Elena Righi”, Lucia Cavazzuti”, Guerrino Predieri”, Armando Franceschellib “Dipartimenro

di Scienze

Biomediche, bServizio

Sezione

di Igiene

di Igiene e Microbiologia, Universitri di Modena, 41100 Modena, Italy Pubblica Azienda, USL Modena, Modena, Italy

Via G. Campi.

,787,

Received23 June 1996; accepted6 October 1996

Abstract We carried out a survey in 16 libraries of the University of Modena, Northern Italy, to assess the indoor exposure to volatile organic compounds (VOCs), including formaldehyde, and total dusts. Data were collected on the main structural characteristics of the buildings; indoor microclimate parameters, such as temperature, relative humidity and ventilation rate were measured and air samples taken inside and outside the libraries. The mean value of total dusts was 190 &- 130 ,ug/m3 with a wide range of values. Formaldehyde was found in only ten out of 16 libraries and the indoor concentrations ranged from 1.70 to 67.8 pg/m3 with an average value of 32.7 f 23.9 pg/m3. On the whole, VOCs were present in all the libraries investigated with an average value was 433 f 267 pg/m3 (range 102-936 pg/m3). No correlation was found among VOCs, formaldehyde and total dusts nor was a significant association observed with microclimatic parameters or the structural characteristics of the buildings. The general situation found in this study suggests no major problems related to indoor pollution. However, some of the pollutants investigated such as total dust and total VOCs deserve further investigation. It is important to identify the possible sources of contaminants and to define the relationship between indoor and outdoor levels of pollutants more accurately, taking into account the effects of air recycling due to natural ventilation systems. Copyright 0 1996 Elsevier Science B.V. Keywords:

Air quality; Pollutants; Volatile organic compounds

1. Introduction

* Corresponding author. Tel.: + 39 059 360084;fax: + 39 059 363057.

Volatile organics compounds (VOCs), including formaldehyde, and total dusts are considered ubiquitous indoor and outdoor pollutants. The levels of these substances in indoor air are often

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higher than those outside. One of the most important studies on VOCs was performed in the USA by the EPA Total Exposure Assessment Methodology Study; it monitored VOC ambient air sam-ples and human breath samples and showed that indoor air concentrations of the VOCs were greater than outdoor levels with indoor/outdoor ratios typically averaging from 2-20 [1,2]. Indoor levels of VOCs and dusts can originate from various construction materials and consumer products commonly found in homes, public buildings and offices. Many VOCs have been studied including aldehydes, aromatic and aliphatic hydrocarbons and halogenated volatile organics. The primary sources of formaldehyde are considered particle board, plywood, medium density fiberboard; other sources include coatings, plastics, paper products, foam insulation and textile materials. Common office supplies and equipment, especially duplicators and copiers, have been found to release dangerous chemicals and some authors have even found formaldehyde being released from bulk paper stores [3,4]. The level of formaldehyde in indoor air has been extensively studied because of the well known health effects, particularly irritation of eyes and respiratory tract, that can occur at very low concentrations [5]. Recently formaldehyde was classified by the International Agency for Research on Cancer (IARC) as a 2A group substance (probably carcinogenic to human) [6]. More than 900 different VOCs besides formaldehyde have been identified in indoor air [7]. They may originate from building materials and products such as adhesives, cleaning agents, drycleaned clothes, deodorizers, textile and synthetic furnishings, copy-machine chemicals, paints etc. The health effects for some of these compounds are known, but the concentrations at which identified health effects occur are usually much greater than those measured in indoor air. Health effects reported for VOCs range from sensory irritation to behavioral, neurotoxic and hepatotoxic effects. Among these compounds, benzene is a well known cancinogen (IARC group 1) and perchloroethylene is group in 2A according to IARC [8,9]. Indoor pollutants include total dusts and their potentially adverse effects on health include allergy and infection. People themselves are the major

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contributors since each person sheds millions of particle& furnishings, draperies and carpets can contribute with fibers and other fragments [4]. A sick building syndrome (SBS) was identified some years ago and many studies suggest an association of SBS with some of these pollutants [lO,ll]. The WHO has identified some typical symptoms of SBS including irritation of the eyes, nose, throat, skin and neurotoxic symptoms, such as mental fatigue or headache [l 11. Recently libraries have also been considered and a sick library syndrome has been identified [ 10,1215]. Studies performed in Stockholm (Sweden) in a sick library disclosed a linear relationship between SBS symptoms prevalence and the mean concentrations of 34 VOCs. The authors also found a dose-effect relationship between VOCs concentration and the increase in mean prevalence of eight specific symptoms suggesting that VOCs may be the cause of the symptoms reported in this building [10,13]. Most studies on indoor air quality were carried out in the USA and in the northern Europe where air conditioning systems are widespread and therefore the indoor environment is fully isolated. The present paper reports the results of a survey carried out inside the libraries of the University of Modena, Northern Italy, to assessindoor air quality by evaluating microclimate parameters and the amount of indoor exposure to VOCs, including formaldehyde, and total dusts.

2. MaterIds

ad methods

This s&y was performed in 16 libraries of the University of Modena, Northern Italy, during a period of 6 months from November 1995 to April 1996. Data were collected on the main structural characteristics of the buildings such as age, floor area and the number of rooms in each library. We coII&ted”information on indoor materials such as wall surfaces, fIoors, windows and ventilation system, furnishings: frequency of cleaning and disinfection of the rooms and books were reported as well ‘as ir&rinat’in~ on the time table and the number‘ of d&y visitors present in the library.

G. Fantuzi

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Indoor air samples were collected to evaluate total dusts, formaldehyde and other VOCs: during each sampling session outdoor air samples were also collected. Inside the libraries, temperature, relative humidity, ventilation and atmospheric pressure were measured in the room where air samples were collected. To control possible confounding effects, a standardized collection protocol was used: prior to collection of air samples, all windows and doors were closed to minimize ventilation and the pumps were placed on a bookcase at about 1.50 m in height. To evaluate total dust, air samples were collected onto 20 mm diameter, 0.80 pm pore size filters (Sartorios GmbH D-3400, Gottingen, FRG), using a sampling pump (Zambelli, mod Chronos, Milano, Italy) with a flow rate at 2 l/min for a period of 4 h and an average total collection volume of 480 1. The samples were dried to constant weight. Formaldehyde detection was performed using a SIPIN sampling pump (mod SP-1, SIPIN, New York, USA). Samples were collected with ORBOTM-22 (SUPELCO, New York, USA) tubes at a flow rate about 50 cm3/min for 4 h, with an average total collection volume of 12 1. Air flow calibration was performed both before and after the sampling period. The formaldehyde samples were refrigerated and routinely analysed within 3 days of sampling. Formaldehyde determination was performed following the NIOSH Method 2502-P and CAM 354, according to which formaldehyde is adsorbed by a sorbent tube coated with N-benzylethanolamine and is converted to 3-benzyloxazolidine by reaction with the N-benzylethanolamine [ 161. The 3-benzyloxazolidine is desorbed from the sorbent with isooctane and the resulting solution is analyzed using a gas chromatograph (Varian 3400) with a flame ionization detector (FID). A Vocal capillary column (length 30 m, inner diameter 0.54 mm, film thickness 3.0 Llrn, SUPELCO, New York, USA) was used. Gas chromatographic parameters were as follows: gas (He) flow rate, 30 ml/min; makeup flow 20 ml/min; oven temperature 150°C; splitness injection 2 10°C; detector temperature 2 10°C.

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51

Calibration was performed by the external standard method. The lower limit of detection (2.5 times base level noise) was 1 pg/m3. Precision was calculated from two duplicate determinations over five different days of standard solutions containing 3-benzyloxazolidine at levels of 20 and 200 ng: variation coefficients were 7.45 and 3.9%, respectively. Formaldehyde values were corrected to a standard temperature of 25°C and an atmospheric pressure of 1013 hPa. VOCs were sampled with a SIPIN sampling pump (mod SP-1, SIPIN, New York, USA) and air samples were collected using CARBOTRAP 300 (SUPELCO, New York, USA) tubes at a flow rate about 25 cm3/min for 4 h with an average total collection volume of 6 1. CARBOTRAP 300 tubes were subsequently thermal desorbed by thermal desorption unit (TDU) (mod 890, SUPELCO, New York, USA). The trapped compounds were introduced into the gas chromatograph (Perkin Elmer Autosystem) equipped with an FID system. A Vocal capillary column (length 30 m, ID 0.53 mm, film thickness 3.0 jlrn, SUPELCO, New York, USA) was used. Gas chromatographic parameters were as follows: gas (He) flow rate, 6 ml/min; make-up gas, (NJ 20 ml/min; initial column temperature. 50°C (1 min); final temperature, 100°C (7 min at 6”C/ min); injector temperature, 150°C; detector temperature, 280°C; range 20, attenuation 2. Calibration was performed by the external standard method. The lower limit of detection (2.5 times base level noise) was 0.33 /-lg/m3 corresponding to 2 ng in 6 1. Precision was calculated from three duplicate determinations over five different days of standard solutions containing benzene, toluene and xylenes at concentrations ranging from 4.4 to 440 ng. Coefficients of variation were 3.3, 2.6 and 3.3% for benzene, toluene and xylenes, respectively. Indoor air temperature, humidity and ventilation were recorded by a TECORA (ITALY) ECOL mod HSA 832 at the beginning and after the end of each sampling period. All measured concentrations were corrected to a standard temperature of 25°C and an atmospheric pressure of 1013 hPa.

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Table 1 Mean values of VOCs and total dusts observed in the 16 libraries of the University of Modena

Total dusts &g/m3) Formaldehyde (pg/m3) VOCs (kg/m3): C,-C, compounds Benzene Toluene Xylenes Total VOCP

No. of positive samples/total samples (%)

Arith. mean

S.D.

Median

Min-max

16/16 (100) lo/16 (62.5)

190 32.7

130 23.9

160 13.6

40-450 1.70-67.8

15/16 15/16 15/16 15/16 16/16

123.5 12.4 51.3 29.0 433.0

151.6 8.9 83.7 11.2 267.1

67.0 10.0 22.0 31.0 296.0

10.0-599.0 4.7-39.0 11.O-46.0 13.0-47.0 102-936

(93.5) (93.5) (93.5) (93.5) (100)

“Total VOCs values represent the amount of various identified and non identified compounds which were revealed in the gas chromatographic analyses and were expressed as n-exane equivalents.

Statistical analyses were performed with the SPSSjPC statistical package [ 171. P-values less than 5% were regarded as significant and non parametric tests of significance (Mann Whitney U-test) were applied. Correlations between parameters were evaluated with Spearman’s rank correlation coefficient. 3. Results All 16 libraries of the University of Modena are located in different buildings in the city of Modena (Italy): nine of them are located in new ones (constructed after 1970) while seven are in ancient buildings (from XVII to XIX set). The floor coating is linoleum (seven libraries), carpet (two libraries), marble and tiles (eight libraries): plaster is always used on wall surfaces. Ten libraries had metal tables and shelves while three are furnished both with antique wood furniture and new office equipment and three libraries contain only antique furniture in wood. All 16 libraries have openable windows with a natural ventilation system and inside .a11 libraries smoking is strictly forbidden. Nine libraries are very small ( I 100 m* with one or two rooms) and are usually open only for university researchers and internal students for short periods of time; six libraries are larger ( > 100-1000 m2) with four or six rooms and about 80 seats; one is wider than 1000 m2. Seven libraries are occupied daily by a large number of students who stay there for several hours to study.

The microclimate parameters showed a mean temperature of 2 1.5 ) 2°C with a minimum value of 19.5”C and a maximum of 26.5”C: mean ventilation rate was 0.020 f 0.004 m/s, while relative humidity showed values ranging from 52 to 70% with a mean value of 58 f 5%, as usually observed in indoor environments during the winter period in our region. All values are within the American Society of Heating, Refrigerating and Air-conditioning Engineers (ASHRAE) standards [ 171. Table 1 summarizes mean concentrations of the investigated substances evaluated in the 16 libraries. Total dusts were found in all 16 libraries and the mean concentration was 190 + 130 pg/m3 with a wide range of values. Formaldehyde was detected in only ten out of 16 libraries and the indoor concentrations ranged from 1.70 to 67.8 it/m3 with an average value of 32.7 + 23.9 ,ug/ VOCs were present in all the libraries investigated; in one library, however, C2-C, compounds, benzene, toluene and xylenes were below the detection limit. Spearman’s correlation coefficients showed a significant correlation between C2-C, compounds and total VOCs (Y = 0.53; P < 0.05); benzene and total VOCs (r = 0.70; P < 0.05); toluene and total VOCs (r = 0.62; P < 0.05); xylenes and total VOCs (Y= 0.58; P < 0.05). Total dust and C2-C, compounds showed a significant correlation (r = 0.64; P < 0.05); no significant correlation was observed between formaldehyde values and the other investigated

G. Fantuzzi et al. : The Science cf the Total Emironment 193 (1996) 49-56 Table 2 Median values of total dust, formaldehyde at different places in the city of Modena Inner Indoor Median Total dusts (Pg/m’) Formaldehyde (pg/m3) VOCs (pg/mz) C, - C, compounds Benzene Toiuene Xylenes Total VOCs” d Total VOCs chromatographic

and other

VOCs

found

inside

the University

city (n = 7) (min-max)

80 (40-450) 22.9 (1.7-67.8) 77 (10-599) I1 (4.7-21) 22.0 (11-53) 38.0 (13-47) 566 (136.-854)

libraries

53

and in outdoor

samples

collected

Suburbs Outdoor Median

()I= 4) (min-max)

Indoor Median

(n = 9) (min-max)

Outdoor Median

(n = 4) fmin -max)

350 (80-650) 21 (4.0-60.6)

210 (40-330) 10.5 (4.0.. 35.6)

200 (40-330) 9.2 (5% 18.0)

175 (56-287) I I (4.2L14.0) 32.5 (1 I -72) 59.0 (16 -96) 584 (247. 895)

67 (29p 127) 8.9 (5.4-39) 24.5 (16-346) 25.5 (14-33) 282 (102-936)

31 (II-.6?) 4.4 (I .9-8.2) 16.0 (9.-34) 24.0 (9.5 -40) 300 (181-437)

values represent the amount of various identified and non analyses and were expressed as n-exane equivalents.

compounds or among the microclimatic parameters and all the substances investigated. Subsequently the libraries were divided into two groups according to their location in the city of Modena: seven libraries are located in the inner city, while nine are located in the suburbs, in the University campus. Table 2 lists the median, minimum and maximum values of total dusts, formaldehyde and VOCs according to the location of the libraries and in both indoor and outdoor samples. Only four outdoor samples in the inner city and four outdoor samples in the suburbs were collected, as the University libraries were very close to each other. Levels of total dust in indoor air samples collected in the libraries in the inner city appeared very low (median = 80 jlg/m3) compared with the corresponding values (median = 2 10 /Lg/m3) found in the libraries located in the suburbs. A different pattern was observed for total dusts measured in outdoor samples: the median outdoor value in samples collected in the inner city (median = 350 /cg/m3) was higher than that in outdoor samples near the libraries outside (median = 200 /Lg/m3). These differences, however, did not reach statistical significance. The values of VOCs and formaldehyde in the indoor air samples collected in the University libraries located in the inner city were generally higher than those collected in the libraries located

identified

compounds

which

were

revealed

in the gas

in the suburbs; the corresponding outdoor concentrations showed the same pattern. However, the non parametric statistical test (Mann Whitney U-test) indicated no statistically significant difference between groups. On the whole, in the inner city libraries outdoor levels tended to be higher than the corresponding indoor values, while in the suburbs an opposite trend was detected but the differences were not statistically significant. This is probably due to the fact that windows are frequently opened depending on the climate of our region. The mean values of the investigated substances did not show statistically significant differences taking into account the main characteristics of the libraries, such as the age of the buildings, the kind of furniture and fittings.

4. Discussion

Many surveys indicate that indoor dusts represent the main source of human exposure to this kind of pollution. Dust in libraries and other indoor environments is a mixture of fibres and irregularly shaped particles: dust particulates, mainly those belonging to the respirable particle class ( < 2.5 pm), may present a risk to health as they are readily breathed deep into the lungs, and can deliver high concentrations of potentially

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harmful substances to body tissues. Particulates may themselves be chemically reactive or act as carriers for other harmful chemical species such as formaldehyde [5]. Recently some studies have suggested a relationship between productive cough, eye irritation and indoor total suspended particulates [19]. Even though few comparable data exist on indoor total dusts levels, our values (range 40-450 pg/m’) are significantly higher than those reported by other authors [14] who found that in the Archives of the Helsinki University Library total dust concentrations varied from 10 to 36 ,ug/m3, while outdoor dust concentrations ranged from 10 to 46 pg/m3. The maximum concentrations of particulates in the range of 0. 1 - 100 pm recommended by the American National Primary Ambient Air Quality Standards, reported in ASHRAE, are 75 pg/m3 (1 year) and 260 pug/m3 (24 h) [18]. Our values are referred to 4 h sampling; but they do suggest that a potential situation of human discomfort could exist. International regulations and guidelines related to emissions of and exposures to formaldehyde have been set in several countries and range from 60 to 500 ,ug/m3 with a preference for 120 pg/m3 [6]. Data from our study show values (range 1.767.8 pg/m3) all well below the limit of 120 ,ug/ m3, similar to the indoor levels of formaldehyde usually found in other libraries [10,12,20]. In only one investigation, performed in Hong Kong, were levels of formaldehyde significantly higher than the recommended values and ranging from 250 to 1250 @g/m’ [15]. Many studies measuring formaldehyde concentrations in residential indoor air suggest that the levels of formaldehyde are often higher than those outside [6]. Our results do not agree with this finding, as indoor and outdoor levels were very similar, perhaps due to the air recycling caused by opening the windows. Individual and total VOCs were investigated by Berlung et al. in Sweden [21]. In this study, one library was investigated and 95 VOCs were identified: levels of toluene and xylenes at most at lo-20 lug/m3 were found, whereas half of the

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remaining compounds appeared below 5 pg/m3, and all others below 1pgg/m3. Many other studies report individual and total VOCs values detected in other public and private places. Hoskins et al. reviewed the levels of xylenes disclosed in several indoor ambients and reported, for public places, a range of 4.7-396 pg/m3 with an average value of 47.7pg/m3 [22]. In another report, Holcomb and Seabrok found a mean value of 29.2 pg/m3 for toluene and 6.5 for benzene in non-smoking public places, and an average value of total VOCs in public places of 3 15.1 pg/m3 with a range of 17.8-1627 pg/m3. suggesting a guideline value of total VOCs equal to 3000 pg/m3 [23]. All these data are similar to our results. In the present study the average value of total VOCs (range 102-936 pg/m3) is 433 pg/m3, in agreement with the previously reported levels and well below the suggested guideline value. However, Molhave suggests a classification into four groups for total VOC values, according to the potential health effects: (i) indoor levels of total VOCs < 200 pg/m3 = comfort; (ii) levels of total VOCs ranging from 200 to 3000 pg/m3: situation of irritation and discomfort if other factors exist; (iii) total VOCs ranging from 3000 to 25 000 pg/m3: discomfort range; (iv) total VOCs > 25 000 pg/m3: toxic range [24]. A conservative level of total VOCs was also recommended by Seifert who suggested a guideline value of 300 pg/m3 [25]. Taking these guideline values into account, the levels of VOCs we found inside some of the 16 libraries of the University of Modena deserve attention and further monitoring. The general situation in this study suggests no major problems related to indoor pollution. However, some of the investigated pollutants such as total dusts and total VOCs deserve further investigation. It is important to identify the possible sources of contaminants and to define the relationship between indoor and outdoor levels of pollutants more accurately, taking into account the effects of air recycling due to natural&ventilation systems. Moreover, it would also be interesting to assess the presence of symptoms usually related to

discomfort, or to the SBS, in order to establish a possible relationship between indoor pollutants, microclimate parameters and human well-being.

Acknowledgements This study was supported by a grant from the Italian Ministry for Scientific and Technological Research (40% and 60%) and a grant from Modena Health Unit (Azienda USL Modena).

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