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Incorrect installation and use of materials as the cause of a severe air pollution incident in a school building
Science of the Total Environment 487 (2014) 255–259
Contents lists available at ScienceDirect
Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv
Incorrect installation and use of materials as the cause of a severe air pollution incident in a school building Rocco Rella ⁎, Alberto Sturaro, Alvise Vianello Institute for the Dynamics of Environmental Processes, C. N. R., C.so Stati Uniti 4, 35127 Padua, Italy
H I G H L I G H T S • • • • •
Epoxy resin floor produced a significant air contamination in a school. School users felt discomfort and irritation of the upper airways and eyes. There was correspondence between the GC/MS chromatograms of air and the floor resin. The indane, or a mixture containing it, was used as diluent. The flooring was to be performed with low VOC emission materials.
a r t i c l e
i n f o
Article history: Received 20 February 2014 Received in revised form 4 April 2014 Accepted 7 April 2014 Available online 3 May 2014 Editor: Adrian Covaci
a b s t r a c t The proofing treatment of the floor slabs with a solvent based material and successive treatment with epoxy resin resulted in significant air contamination in a primary school. The contamination caused illnesses in many occupants of school. The GC/MS investigations of the air showed the presence of indane and other aromatic solvents, which was unusual as they are not correlated to outdoor pollution and derived from inner layers of the new flooring. The total concentration of these chemicals in air was in the order of several mg/m3. © 2014 Elsevier B.V. All rights reserved.
Keywords: Aromatic solvents Epoxy resin floor Indane Tenax TA Radiello
1. Introduction People spend much of their time surrounded by sources of air pollution: consumer products, gas appliances, building materials, cigarettes, and furniture can all contribute to the problem. Yet, the toxic emissions from many of these sources are not controlled or are only partially controlled by Environmental Protection Agencies. People spend more than 80% of their 24-hour day indoors. If pollutants are present indoors, people will inhale them. For most of the common people, the amount of air pollution breathed is primarily determined by what is in indoor air. Typically indoor air pollution consists of a mix of gases or particles that can harm our health. These pollutants can build up rapidly indoors to levels much higher than those usually found outdoors. Generally, the indoor/ outdoor ratio of VOCs is above unity, showing the important influence ⁎ Corresponding author at: IDPA-CNR, C.so Stati Uniti, 4, 35127 Padua, Italy. Tel.: +39 498295668; fax: +39 498295662. E-mail address: [email protected] (R. Rella).
http://dx.doi.org/10.1016/j.scitotenv.2014.04.031 0048-9697/© 2014 Elsevier B.V. All rights reserved.
of indoor sources on the air quality (Pegas et al., 2012). This is especially true if large amounts of a pollutant are released indoors. The effects of indoor air pollutants range from short-term effects, such as eye and throat irritation, to long-term effects, including respiratory disease. Infants, the elderly, those with heart and lung diseases, people with asthma, and individuals who have developed extreme sensitivity to chemicals are particularly susceptible to the health effects of indoor pollutants. The most effective way to protect these people from indoor air pollution is to prevent or minimize their release. Since 1989, many building materials, products, and furnishings were found to emit a large number of organic chemicals into the air (Alves et al., 2013; Bohm et al., 2012; Pegas et al., 2012; Rella et al., 2012; Yamashita et al., 2012; Yu and Kim, 2010; Weschler, 2009; Destaillats et al., 2008; Watt and Colston, 2003; Schwenk et al., 2002; Jones, 1999; Bent and Zwiener, 1996; Fantuzzi et al., 1996; Molhave, 1982). Most of these chemicals are either volatile organic compounds — VOCs (Alves et al., 2013; Bohm et al., 2012; Rella et al., 2012; Yamashita et al., 2012; Yu and Kim, 2010; Destaillats et al., 2008; Fantuzzi et al., 1996; Molhave,
256
R. Rella et al. / Science of the Total Environment 487 (2014) 255–259
1982) or semi-volatile organic compounds — SVOCs (Watt and Colston, 2003; Schwenk et al., 2002). Building designers, owners, operators, occupants, and product manufacturers are increasingly involved in reducing the problems caused by indoor air contaminants emitted from building products and furnishings. Indoor air quality will be enhanced by utilizing materials that have minimal emissions of volatile organic compounds. These materials should be installed using minimal quantities of volatile compounds (preferably none) and should not require cleaning with harsh chemicals. This should be demonstrated by the manufacturer for each product and should be reported on a fact sheet after appropriate testing. The use of unsuitable building materials and procedures represents a frequent source of harmful effects and illness for the people occupying the building (Bohm et al., 2012; Watt and Colston, 2003; Schwenk et al., 2002; Molhave, 1982). This paper is to highlight a particularly severe problem that was verified in a new building projected and realized for a primary school. It was and remains the school for hundreds of children, from six to eleven years old, and the work place of the teachers, administrative and technical personnel. Since the opening of the new school, the users felt discomfort, and irritation of the upper airways and eyes. The problems were accentuated, in the winter season, by the activation of the under-floor heating. After a long series of complaints and surveys on the air quality, the competent authorities closed the school, allocating, with numerous problems, students and teachers to other locations. While confirming the inadequacy of the air quality, the causes were not identified until the intervention of our laboratory. This paper summarizes the analytical chemistry carried out, the results obtained, the identification of the origin of the problem and the dynamics of the environmental pollution that was responsible for the discomfort felt in the new school. 2. Materials and methods 2.1. The school The building had a main body of circular shape on two floors with a large hall giving access to six classrooms, to the many didactical environments, and to the rooms for staff and services. Two flights of stairs led to the semi-circular first floor, where nine classrooms, the services and some didactical environments were located. From the circular hall, a long corridor led to the gym and to the related services. The building housed 218 students, teachers, and administrative and technical staff. At the time of sampling, the school was completely empty, devoid of any furniture. The available materials were only those of construction. Plaster and paint were declared free of solvents. Only the ceiling of the entrance was formed by fir beams and planks, treated, as in the project, with water-based paints and primers. The internal and external fixtures were in painted aluminum. Over 80% of the floor was formed by epoxy resin. Only the services and the gym had floors in gres and specific materials respectively. The heating system consisted of underfloor heating panels fed with a low-temperature boiler. The maximal temperature of the water inside of the radiant panels was 37 °C, thermo-regulated, by electronic control unit, in function of the outside temperature up to a minimum of 28–30 °C. The air was continuously filtered and reintroduced after mixing with fresh air, 2.5 vol./h for classrooms and dressing rooms 7 vol./h for the services.
retained their original structure and the chemical components to be analyzed by GC/MS. The materials collected were stored in glass jars prior to GC/MS analysis. The results were used to interpret the indoor air quality results. The indoor air contaminants were sampled using Tenax TA, active adsorbents, by flushing air at 50 ml/min for 2 h (U.S. EPA, 1999). The Radiello passive system was also used, by exposing the cartridges for a week to ensure a significant capture of volatile chemicals. The four sampling sites were chosen on the basis of a previous report by the municipality on the level of uneasiness perceived by the students and staff of the school. The selected sites were also representative of the entire building which was emptied of all the furniture and school supplies after abandonment. The sampling points chosen were a classroom, the gym and a changing room on the ground floor and a classroom on the first floor. Moreover, at the same points, resin floor samples were collected, together with the materials mentioned above. Table 1 reports the sampling sites, the sampling systems, the materials collected and additional information on the sampling procedures.
2.3. Chemicals and materials The high purity (N 98%) VOC standards used for the identification and quantification of air pollutants, and the Radiello, passive adsorbents, specific for BTEX sampling were purchased from AldrichChimica (Milan, Italy). The Tenax TA (35/60 mesh), cartridges for active sampling, were from DTO Service (Spinea, Venice, Italy).
2.4. Analytical instrumentation All the determinations from the Tenax TA and Radiello cartridges were performed by thermal desorption–gas chromatography–mass spectrometry (TD/GC/MS). The analytical instrumentation composed of a Markes Unity 2 thermal desorption unit coupled with a HP 7890A GC and HP 5975C quadrupole mass spectrometer. The thermal desorption conditions were 10 min at 250 °C for the Tenax TA and 10 min at 300 °C for the Radiello cartridges, with the transfer line at 140 °C and a total flow rate of 80 ml/min. The solid materials such as floor resins, wall material, and wood were analyzed directly by placing 6 mg of each sample into the thermal desorption cold trap (TCT) device tube and heating it for 5 min at 80 °C. GC separation was performed using a HP-5MS capillary column (30 m length; 0.25 mm internal diameter and 0.25 mm film thickness) with the following temperature program: 50 °C for 3 min, followed by a ramp of 10 °C/min up to 250 °C and hold for 15 min at a column flow of 1.5 ml/min. The analytes were determined using the quadrupole mass analyzer operating in scan acquisition mode in the mass range between 50 and 300 Da, with electron ionization at 70 eV with the ion source at 230 °C. Table 1 The main samples collected in the school. Sample site
Sample
Notes
Ground floor, classroom
Tenax TA Floor resin Wall material Radiello BTEX Tenax TA Floor resin Radiello BTEX Floor resin Wood beam Tenax TA Floor resin Radiello BTEX Tenax TA Floor resin Radiello BTEX Tenax TA
5.04 l Drill (4 Drill (2 7 days 5.16 l Drill (4 7 days Drill (4 Drill (2 4.76 l Drill (4 7 days 4.84 l Drill (4 7 days 4.76 l
Ground floor, changing room
2.2. Samplings Sampling was executed during the winter season. The internal and external temperatures were 20 °C and below 10 °C respectively. The materials inside the school, such as paints, plaster, fixtures, and wood were collected using a drill at different sites of the school. A hole saw with 25 mm diameter and a low speed penetration were used, except for the fixtures where a 4 mm tip for metal was used. This operation has ensured the collection of the materials that almost completely
Ground floor, gym Entrance hall First floor, classroom
First floor, English classroom
Outdoor control
cm deep) cm deep)
cm deep) cm deep) cm deep) cm deep)
cm deep)
2.00
toluene 4.00
6.00
8.00
10.00
benzoic acid
Indane
2000000
benzaldehyde
1e+07
C3-Benzenes
xylenes
2e+07
benzene
Abundance (counts)
3e+07
257
benzylalcohol
R. Rella et al. / Science of the Total Environment 487 (2014) 255–259
12.00
14.00
Retention time (min) Fig. 1. TD/GC/MS total ion chromatogram from the Tenax TA, changing room sample.
school where children spend a lot of their daily time. The presence of aromatic compounds such as benzene and toluene could be due to various internal and external sources in and around the school; this is not the case for indane, benzyl alcohol or benzaldehyde, as they are not normally present as contaminants in the air. In addition, the seasonal trend and the increase following the activation of the heating system indicated an internal source with a continuous emission that is directly influenced by the floor heating system. The construction materials most representative within the school are reported in Table 1; they were analyzed using the same technique as the air samples (TD/GC/MS). Comparing the chromatographic data from each analyzed material the following evidence were found:
2.5. Quantification Quantification of the samples trapped on Tenax TA was carried out against an external calibration produced by spiking blank tubes with standard solutions followed by desorption as described above. For the quantification of the Radiello samples, a calibration was made by introducing known concentrations of each standard, dissolved in methanol, into 10 ml vials containing fresh cartridges. The vials were heated at 40 °C for 2 h and the cartridges were then analyzed. 3. Results and discussion Both samplers, Radiello and Tenax TA showed the presence of the same solvent profile in indoor air, at different concentrations for each monitoring site. The GC/MS solvent profile was very different from the external control, so its origin was not from outdoor air pollution. The GC/MS analysis detected other organic solvents in addition to toluene, xylenes and higher homologues. Fig. 1 shows the GC/MS total ion chromatogram from analysis of Tenax, while the corresponding Radiello cartridges gave an overload signal, due to saturation of the adsorbent because an excessively long sampling time was used. Despite this overload, the same solvent profile found with Tenax was identified. The results from the Tenax TA analyses were used for the quantitation of the pollutants at each site; the results are reported in Table 2. All the data show the unusual presence of indane, together with some aromatic compounds as xylenes and C3-benzenes. Moreover benzyl alcohol and benzaldehyde were present in all air samples. A partial contribution from outdoor pollution may be considered for xylenes and C3-benzenes but the higher mass contaminants cannot be explained by outdoor contamination. The concentrations of the main contaminants were in the order of several mg/m3. Although such concentrations are under the working place threshold limits, they are certainly not negligible for environments such as a
✓ there were no overlaps between the air chromatograms and those from the walls, wood beams or gym floor; ✓ there was a high correspondence between the total ion chromatograms of air and the floor resin that was sampled together with the floor slab as shown in Fig. 2. 3.1. Causes of the pollution The analyses shown above demonstrated that the origin of the pollution was the floor. However, it was not clear why. In the original project, the municipality had specified the use of materials with low emissions of VOCs. Also, it was not clear why indane was present; it is an unusual solvent that is not present among the main air pollutants (U.S. EPA, 1999). The initial project of the school expected gres flooring, which is a kind of nonporous ceramic tiling. Subsequently, a variation was proposed and accepted. The gres was substituted with a self-leveling polymeric floor, consisting of a top polymer layer of about 2 mm whose technical data sheet reported: “… formulation based on epoxy resins, two-component, pigmented, containing mineral fillers and extenders in powder form”.
Table 2 VOC concentrations in air from four most representative sites of the school. Retention index
Ground floor classroom
Ground floor changing room
First floor English classroom
First floor classroom
2.06 1.43 1.30 0.96
8.96 3.07 0.58 0.95
0.68 0.50 0.32 0.71
1.43 1.10 0.49 0.94
0.30 0.13 6.20 6.97
0.18 0.65 14.42
0.47 0.06 2.75
0.40 0.15 4.51
mg/m3 Indane C3-benzenes Xylenes Benzaldehyde+ benzyl alcohol Benzene + toluene Chlorinated compounds Total conc. Average conc.
1170
1133 1208
Indane
R. Rella et al. / Science of the Total Environment 487 (2014) 255–259
Benzaldehyde
5000000
C3-benzenes
1e+07 xylenes
Abundance (counts)
1.5e+07
Benzylalcohol
258
1000000 2.00
4.00
6.00
8.00
10.00
12.00
14.00
Time (min) Fig. 2. TD/GC/MS total ion chromatograms of air (blue line) and floor resin (red line) from the changing room.
The laying of the new floor required the proofing of the underlayer that had been already prepared for the gres. The proofing was to be performed with low VOC emission materials. This condition was disregarded by the company responsible for the flooring which had hoped that the polymeric layer would prevent the evaporation of the residual solvent. The proof surface was made by a “ … two-component epoxy impregnating product, diluted in special solvents with high wettability. … For its particular solvent composition it allows the passage of the epoxy binder through the capillarity of the support, thus creating a substrate anchor suitable to receive all subsequent treatments resin base” (from the Technical data sheet). The indane, or a mixture containing it, was used to dilute the impregnating product. The company did not observe the time required for the complete evaporation of the solvent. It was found that during the exothermic phases of the polymerization the evaporating solvents caused bubbles and deformations,
making the layer permeable. The unexpected permeability allowed the solvents, still present in the slab, to evaporate with a speed influenced by the temperature of the floor heating system, as seen in Fig. 3. A technical report, by the same company, states that the application of the epoxy resin must be performed on a surface without any porosity or trace of solvent (Oriani et al., 2005).
4. Conclusions and implications The school environment was heavily contaminated by volatile organic compounds (VOCs). The solvent indane was almost 50% of TVOC. The extent of the pollution was likely to have caused the various symptoms and discomfort found by the staff and students hopefully with no long term toxic effects (Molhave, 1990). The origins of the
Fig. 3. In the top left, macroscopic appearance of an area of the self-leveling epoxy flooring. In the top right, macroscopic appearance of the section of the floor with the under layer. In the lower left, a particular detail of the polymeric layer section using stereo optical microscopy. At the lower left, The surface of the polymeric layer under scanning electron microscopy.
R. Rella et al. / Science of the Total Environment 487 (2014) 255–259
pollution were the materials used in the laying of the floor which showed several macroscopic and microscopic anomalies. The microscopic structure of the resin layer appeared uneven with small channels and interconnected cells that communicated with the surface through 5–10 micro pores. The inhomogeneity of the polymer layer was caused by the indane and other solvents that were still present at high concentrations in the slab during the polymerization of the resin. The permeable layer of resin slowed down but did not block the evaporation of solvents used for the proofing/consolidation of the concrete support. Considering the concentrations of residual solvents, the evaporation and diffusive pathways, it was conceivable that the phenomenon would not stop in the short term and that the pollution would follow a fluctuating trend with seasonal peaks dependent on the floor temperature and the degree of aeration of the environments. The municipality, following the results of this work, independently of the ongoing civil claim against the company which laid the flooring, removed the entire floor and the underlying layers to replace them with the originally chosen materials. Successively the municipality has won the court case and the entire cost of the damage was charged to the company. References Alves CA, Calvo AI, Castro A, Fraile R, Evtyugina M, Bate-Epey EF. Indoor air quality in two university sports facilities. Aerosol Air Quality Res 2013;13:1723–30. Bent S, Zwiener G. Solvent emissions in school building after using a construction moisture protection substance. Gesundheitswesen 1996;58:234–6. Bohm M, Salem MZM, Srba J. Formaldehyde emission monitoring from a variety of solid wood, plywood, blockboard and flooring products manufactured for building and furnishing materials. J Hazard Mater 2012;221–222:68–79.
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Destaillats H, Maddalena RL, Singer BC, Hodgson AT, McKone E. Indoor pollutants emitted by office equipment: a review of reported data and information needs. Atmos Environ 2008;42:1371–88. Fantuzzi G, Aggazzotti G, Righi E, Cavazzuti L, Predieri G, Franceschelli A. Indoor air quality in the university libraries of Modena (Italy). Sci Total Environ 1996;193:49–56. Jones AP. Indoor air quality and health. Atmos Environ 1999;33:4535–64. Molhave L. Indoor air due to organic gases and vapours of solvents in building materials. Environ Int 1982;8:117–27. Molhave L. Volatile organic compounds, indoor air quality and health. Proceedings of the 5th International Conference on Indoor Air Quality and Climate, Indoor Air '90, 5. 1990. p. 15–34. Oriani A, Bellometti D, Dari A, Invernizzi A, Penati F, Taddei M, Vavassori E. Il Codice di Buona Pratica. Roma: Comitato Tecnico Resine CONPAVIPER; 2005. Pegas PN, Nunes T, Alves CA, Silva JR, Vieira SLA, Caseiro A, et al. Indoor and outdoor characterisation of organic and inorganic compounds in city centre and suburban elementary school of Aveiro, Portugal. Atmos Environ 2012;55:80–9. Rella R, Sturaro A, Vianello A. 2-Butoxyethanol from cleaning products responsible for complaints in workplaces: a case study. J Environ Monit 2012;14:2659–62. Schwenk M, Gabrio T, Papke O, Wallenhorst T. Human bio-monitoring of polychlorinated biphenyls and polychlorinated dibenzodioxins and dibenzofuranes in teachers working in a PCB-contaminated school. Chemosphere 2002;47:229–33. U.S. EPA. Compendium of methods for the determination of toxic organic compounds in ambient air, Methods TO-17. Determination of volatile compounds in ambient air using active sampling onto sorbent tubes. 2nd ed. 1999 [Cincinnati]. Watt D, Colston B. Preliminary investigations of pentachlorophenol emissions from biocide-treated masonry: a source of indoor air contamination. Build Environ 2003; 38:1385–8. Weschler CJ. Changes in indoor pollutants since 1950s. Atmos Environ 2009;43:153–69. Yamashita S, Kume K, Horiike T, Honma N, Fusaya M, Amagai T. Emission sources and their contribution to indoor air pollution by carbonyl compounds in a school and a residential building in Shizuoka, Japan. Indoor Built Environ 2012;21:392–402. Yu CWF, Kim JT. Building pathology, investigation of sick buildings — VOC emissions. Indoor Built Environ 2010;19:30–9.
Contents lists available at ScienceDirect
Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv
Incorrect installation and use of materials as the cause of a severe air pollution incident in a school building Rocco Rella ⁎, Alberto Sturaro, Alvise Vianello Institute for the Dynamics of Environmental Processes, C. N. R., C.so Stati Uniti 4, 35127 Padua, Italy
H I G H L I G H T S • • • • •
Epoxy resin floor produced a significant air contamination in a school. School users felt discomfort and irritation of the upper airways and eyes. There was correspondence between the GC/MS chromatograms of air and the floor resin. The indane, or a mixture containing it, was used as diluent. The flooring was to be performed with low VOC emission materials.
a r t i c l e
i n f o
Article history: Received 20 February 2014 Received in revised form 4 April 2014 Accepted 7 April 2014 Available online 3 May 2014 Editor: Adrian Covaci
a b s t r a c t The proofing treatment of the floor slabs with a solvent based material and successive treatment with epoxy resin resulted in significant air contamination in a primary school. The contamination caused illnesses in many occupants of school. The GC/MS investigations of the air showed the presence of indane and other aromatic solvents, which was unusual as they are not correlated to outdoor pollution and derived from inner layers of the new flooring. The total concentration of these chemicals in air was in the order of several mg/m3. © 2014 Elsevier B.V. All rights reserved.
Keywords: Aromatic solvents Epoxy resin floor Indane Tenax TA Radiello
1. Introduction People spend much of their time surrounded by sources of air pollution: consumer products, gas appliances, building materials, cigarettes, and furniture can all contribute to the problem. Yet, the toxic emissions from many of these sources are not controlled or are only partially controlled by Environmental Protection Agencies. People spend more than 80% of their 24-hour day indoors. If pollutants are present indoors, people will inhale them. For most of the common people, the amount of air pollution breathed is primarily determined by what is in indoor air. Typically indoor air pollution consists of a mix of gases or particles that can harm our health. These pollutants can build up rapidly indoors to levels much higher than those usually found outdoors. Generally, the indoor/ outdoor ratio of VOCs is above unity, showing the important influence ⁎ Corresponding author at: IDPA-CNR, C.so Stati Uniti, 4, 35127 Padua, Italy. Tel.: +39 498295668; fax: +39 498295662. E-mail address: [email protected] (R. Rella).
http://dx.doi.org/10.1016/j.scitotenv.2014.04.031 0048-9697/© 2014 Elsevier B.V. All rights reserved.
of indoor sources on the air quality (Pegas et al., 2012). This is especially true if large amounts of a pollutant are released indoors. The effects of indoor air pollutants range from short-term effects, such as eye and throat irritation, to long-term effects, including respiratory disease. Infants, the elderly, those with heart and lung diseases, people with asthma, and individuals who have developed extreme sensitivity to chemicals are particularly susceptible to the health effects of indoor pollutants. The most effective way to protect these people from indoor air pollution is to prevent or minimize their release. Since 1989, many building materials, products, and furnishings were found to emit a large number of organic chemicals into the air (Alves et al., 2013; Bohm et al., 2012; Pegas et al., 2012; Rella et al., 2012; Yamashita et al., 2012; Yu and Kim, 2010; Weschler, 2009; Destaillats et al., 2008; Watt and Colston, 2003; Schwenk et al., 2002; Jones, 1999; Bent and Zwiener, 1996; Fantuzzi et al., 1996; Molhave, 1982). Most of these chemicals are either volatile organic compounds — VOCs (Alves et al., 2013; Bohm et al., 2012; Rella et al., 2012; Yamashita et al., 2012; Yu and Kim, 2010; Destaillats et al., 2008; Fantuzzi et al., 1996; Molhave,
256
R. Rella et al. / Science of the Total Environment 487 (2014) 255–259
1982) or semi-volatile organic compounds — SVOCs (Watt and Colston, 2003; Schwenk et al., 2002). Building designers, owners, operators, occupants, and product manufacturers are increasingly involved in reducing the problems caused by indoor air contaminants emitted from building products and furnishings. Indoor air quality will be enhanced by utilizing materials that have minimal emissions of volatile organic compounds. These materials should be installed using minimal quantities of volatile compounds (preferably none) and should not require cleaning with harsh chemicals. This should be demonstrated by the manufacturer for each product and should be reported on a fact sheet after appropriate testing. The use of unsuitable building materials and procedures represents a frequent source of harmful effects and illness for the people occupying the building (Bohm et al., 2012; Watt and Colston, 2003; Schwenk et al., 2002; Molhave, 1982). This paper is to highlight a particularly severe problem that was verified in a new building projected and realized for a primary school. It was and remains the school for hundreds of children, from six to eleven years old, and the work place of the teachers, administrative and technical personnel. Since the opening of the new school, the users felt discomfort, and irritation of the upper airways and eyes. The problems were accentuated, in the winter season, by the activation of the under-floor heating. After a long series of complaints and surveys on the air quality, the competent authorities closed the school, allocating, with numerous problems, students and teachers to other locations. While confirming the inadequacy of the air quality, the causes were not identified until the intervention of our laboratory. This paper summarizes the analytical chemistry carried out, the results obtained, the identification of the origin of the problem and the dynamics of the environmental pollution that was responsible for the discomfort felt in the new school. 2. Materials and methods 2.1. The school The building had a main body of circular shape on two floors with a large hall giving access to six classrooms, to the many didactical environments, and to the rooms for staff and services. Two flights of stairs led to the semi-circular first floor, where nine classrooms, the services and some didactical environments were located. From the circular hall, a long corridor led to the gym and to the related services. The building housed 218 students, teachers, and administrative and technical staff. At the time of sampling, the school was completely empty, devoid of any furniture. The available materials were only those of construction. Plaster and paint were declared free of solvents. Only the ceiling of the entrance was formed by fir beams and planks, treated, as in the project, with water-based paints and primers. The internal and external fixtures were in painted aluminum. Over 80% of the floor was formed by epoxy resin. Only the services and the gym had floors in gres and specific materials respectively. The heating system consisted of underfloor heating panels fed with a low-temperature boiler. The maximal temperature of the water inside of the radiant panels was 37 °C, thermo-regulated, by electronic control unit, in function of the outside temperature up to a minimum of 28–30 °C. The air was continuously filtered and reintroduced after mixing with fresh air, 2.5 vol./h for classrooms and dressing rooms 7 vol./h for the services.
retained their original structure and the chemical components to be analyzed by GC/MS. The materials collected were stored in glass jars prior to GC/MS analysis. The results were used to interpret the indoor air quality results. The indoor air contaminants were sampled using Tenax TA, active adsorbents, by flushing air at 50 ml/min for 2 h (U.S. EPA, 1999). The Radiello passive system was also used, by exposing the cartridges for a week to ensure a significant capture of volatile chemicals. The four sampling sites were chosen on the basis of a previous report by the municipality on the level of uneasiness perceived by the students and staff of the school. The selected sites were also representative of the entire building which was emptied of all the furniture and school supplies after abandonment. The sampling points chosen were a classroom, the gym and a changing room on the ground floor and a classroom on the first floor. Moreover, at the same points, resin floor samples were collected, together with the materials mentioned above. Table 1 reports the sampling sites, the sampling systems, the materials collected and additional information on the sampling procedures.
2.3. Chemicals and materials The high purity (N 98%) VOC standards used for the identification and quantification of air pollutants, and the Radiello, passive adsorbents, specific for BTEX sampling were purchased from AldrichChimica (Milan, Italy). The Tenax TA (35/60 mesh), cartridges for active sampling, were from DTO Service (Spinea, Venice, Italy).
2.4. Analytical instrumentation All the determinations from the Tenax TA and Radiello cartridges were performed by thermal desorption–gas chromatography–mass spectrometry (TD/GC/MS). The analytical instrumentation composed of a Markes Unity 2 thermal desorption unit coupled with a HP 7890A GC and HP 5975C quadrupole mass spectrometer. The thermal desorption conditions were 10 min at 250 °C for the Tenax TA and 10 min at 300 °C for the Radiello cartridges, with the transfer line at 140 °C and a total flow rate of 80 ml/min. The solid materials such as floor resins, wall material, and wood were analyzed directly by placing 6 mg of each sample into the thermal desorption cold trap (TCT) device tube and heating it for 5 min at 80 °C. GC separation was performed using a HP-5MS capillary column (30 m length; 0.25 mm internal diameter and 0.25 mm film thickness) with the following temperature program: 50 °C for 3 min, followed by a ramp of 10 °C/min up to 250 °C and hold for 15 min at a column flow of 1.5 ml/min. The analytes were determined using the quadrupole mass analyzer operating in scan acquisition mode in the mass range between 50 and 300 Da, with electron ionization at 70 eV with the ion source at 230 °C. Table 1 The main samples collected in the school. Sample site
Sample
Notes
Ground floor, classroom
Tenax TA Floor resin Wall material Radiello BTEX Tenax TA Floor resin Radiello BTEX Floor resin Wood beam Tenax TA Floor resin Radiello BTEX Tenax TA Floor resin Radiello BTEX Tenax TA
5.04 l Drill (4 Drill (2 7 days 5.16 l Drill (4 7 days Drill (4 Drill (2 4.76 l Drill (4 7 days 4.84 l Drill (4 7 days 4.76 l
Ground floor, changing room
2.2. Samplings Sampling was executed during the winter season. The internal and external temperatures were 20 °C and below 10 °C respectively. The materials inside the school, such as paints, plaster, fixtures, and wood were collected using a drill at different sites of the school. A hole saw with 25 mm diameter and a low speed penetration were used, except for the fixtures where a 4 mm tip for metal was used. This operation has ensured the collection of the materials that almost completely
Ground floor, gym Entrance hall First floor, classroom
First floor, English classroom
Outdoor control
cm deep) cm deep)
cm deep) cm deep) cm deep) cm deep)
cm deep)
2.00
toluene 4.00
6.00
8.00
10.00
benzoic acid
Indane
2000000
benzaldehyde
1e+07
C3-Benzenes
xylenes
2e+07
benzene
Abundance (counts)
3e+07
257
benzylalcohol
R. Rella et al. / Science of the Total Environment 487 (2014) 255–259
12.00
14.00
Retention time (min) Fig. 1. TD/GC/MS total ion chromatogram from the Tenax TA, changing room sample.
school where children spend a lot of their daily time. The presence of aromatic compounds such as benzene and toluene could be due to various internal and external sources in and around the school; this is not the case for indane, benzyl alcohol or benzaldehyde, as they are not normally present as contaminants in the air. In addition, the seasonal trend and the increase following the activation of the heating system indicated an internal source with a continuous emission that is directly influenced by the floor heating system. The construction materials most representative within the school are reported in Table 1; they were analyzed using the same technique as the air samples (TD/GC/MS). Comparing the chromatographic data from each analyzed material the following evidence were found:
2.5. Quantification Quantification of the samples trapped on Tenax TA was carried out against an external calibration produced by spiking blank tubes with standard solutions followed by desorption as described above. For the quantification of the Radiello samples, a calibration was made by introducing known concentrations of each standard, dissolved in methanol, into 10 ml vials containing fresh cartridges. The vials were heated at 40 °C for 2 h and the cartridges were then analyzed. 3. Results and discussion Both samplers, Radiello and Tenax TA showed the presence of the same solvent profile in indoor air, at different concentrations for each monitoring site. The GC/MS solvent profile was very different from the external control, so its origin was not from outdoor air pollution. The GC/MS analysis detected other organic solvents in addition to toluene, xylenes and higher homologues. Fig. 1 shows the GC/MS total ion chromatogram from analysis of Tenax, while the corresponding Radiello cartridges gave an overload signal, due to saturation of the adsorbent because an excessively long sampling time was used. Despite this overload, the same solvent profile found with Tenax was identified. The results from the Tenax TA analyses were used for the quantitation of the pollutants at each site; the results are reported in Table 2. All the data show the unusual presence of indane, together with some aromatic compounds as xylenes and C3-benzenes. Moreover benzyl alcohol and benzaldehyde were present in all air samples. A partial contribution from outdoor pollution may be considered for xylenes and C3-benzenes but the higher mass contaminants cannot be explained by outdoor contamination. The concentrations of the main contaminants were in the order of several mg/m3. Although such concentrations are under the working place threshold limits, they are certainly not negligible for environments such as a
✓ there were no overlaps between the air chromatograms and those from the walls, wood beams or gym floor; ✓ there was a high correspondence between the total ion chromatograms of air and the floor resin that was sampled together with the floor slab as shown in Fig. 2. 3.1. Causes of the pollution The analyses shown above demonstrated that the origin of the pollution was the floor. However, it was not clear why. In the original project, the municipality had specified the use of materials with low emissions of VOCs. Also, it was not clear why indane was present; it is an unusual solvent that is not present among the main air pollutants (U.S. EPA, 1999). The initial project of the school expected gres flooring, which is a kind of nonporous ceramic tiling. Subsequently, a variation was proposed and accepted. The gres was substituted with a self-leveling polymeric floor, consisting of a top polymer layer of about 2 mm whose technical data sheet reported: “… formulation based on epoxy resins, two-component, pigmented, containing mineral fillers and extenders in powder form”.
Table 2 VOC concentrations in air from four most representative sites of the school. Retention index
Ground floor classroom
Ground floor changing room
First floor English classroom
First floor classroom
2.06 1.43 1.30 0.96
8.96 3.07 0.58 0.95
0.68 0.50 0.32 0.71
1.43 1.10 0.49 0.94
0.30 0.13 6.20 6.97
0.18 0.65 14.42
0.47 0.06 2.75
0.40 0.15 4.51
mg/m3 Indane C3-benzenes Xylenes Benzaldehyde+ benzyl alcohol Benzene + toluene Chlorinated compounds Total conc. Average conc.
1170
1133 1208
Indane
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Benzaldehyde
5000000
C3-benzenes
1e+07 xylenes
Abundance (counts)
1.5e+07
Benzylalcohol
258
1000000 2.00
4.00
6.00
8.00
10.00
12.00
14.00
Time (min) Fig. 2. TD/GC/MS total ion chromatograms of air (blue line) and floor resin (red line) from the changing room.
The laying of the new floor required the proofing of the underlayer that had been already prepared for the gres. The proofing was to be performed with low VOC emission materials. This condition was disregarded by the company responsible for the flooring which had hoped that the polymeric layer would prevent the evaporation of the residual solvent. The proof surface was made by a “ … two-component epoxy impregnating product, diluted in special solvents with high wettability. … For its particular solvent composition it allows the passage of the epoxy binder through the capillarity of the support, thus creating a substrate anchor suitable to receive all subsequent treatments resin base” (from the Technical data sheet). The indane, or a mixture containing it, was used to dilute the impregnating product. The company did not observe the time required for the complete evaporation of the solvent. It was found that during the exothermic phases of the polymerization the evaporating solvents caused bubbles and deformations,
making the layer permeable. The unexpected permeability allowed the solvents, still present in the slab, to evaporate with a speed influenced by the temperature of the floor heating system, as seen in Fig. 3. A technical report, by the same company, states that the application of the epoxy resin must be performed on a surface without any porosity or trace of solvent (Oriani et al., 2005).
4. Conclusions and implications The school environment was heavily contaminated by volatile organic compounds (VOCs). The solvent indane was almost 50% of TVOC. The extent of the pollution was likely to have caused the various symptoms and discomfort found by the staff and students hopefully with no long term toxic effects (Molhave, 1990). The origins of the
Fig. 3. In the top left, macroscopic appearance of an area of the self-leveling epoxy flooring. In the top right, macroscopic appearance of the section of the floor with the under layer. In the lower left, a particular detail of the polymeric layer section using stereo optical microscopy. At the lower left, The surface of the polymeric layer under scanning electron microscopy.
R. Rella et al. / Science of the Total Environment 487 (2014) 255–259
pollution were the materials used in the laying of the floor which showed several macroscopic and microscopic anomalies. The microscopic structure of the resin layer appeared uneven with small channels and interconnected cells that communicated with the surface through 5–10 micro pores. The inhomogeneity of the polymer layer was caused by the indane and other solvents that were still present at high concentrations in the slab during the polymerization of the resin. The permeable layer of resin slowed down but did not block the evaporation of solvents used for the proofing/consolidation of the concrete support. Considering the concentrations of residual solvents, the evaporation and diffusive pathways, it was conceivable that the phenomenon would not stop in the short term and that the pollution would follow a fluctuating trend with seasonal peaks dependent on the floor temperature and the degree of aeration of the environments. The municipality, following the results of this work, independently of the ongoing civil claim against the company which laid the flooring, removed the entire floor and the underlying layers to replace them with the originally chosen materials. Successively the municipality has won the court case and the entire cost of the damage was charged to the company. References Alves CA, Calvo AI, Castro A, Fraile R, Evtyugina M, Bate-Epey EF. Indoor air quality in two university sports facilities. Aerosol Air Quality Res 2013;13:1723–30. Bent S, Zwiener G. Solvent emissions in school building after using a construction moisture protection substance. Gesundheitswesen 1996;58:234–6. Bohm M, Salem MZM, Srba J. Formaldehyde emission monitoring from a variety of solid wood, plywood, blockboard and flooring products manufactured for building and furnishing materials. J Hazard Mater 2012;221–222:68–79.
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