Indoor molds, bacteria, microbial volatile organic compounds and plasticizers in schools--associations with asthma and respiratory symptoms in pupils

We investigated asthma and atopy in relation to microbial and plasticizer exposure. Pupils in eight primary schools in Uppsala (Sweden) answered a questionnaire, 1014 (68%) participated. Totally, 7.7% reported doctor-diagnosed asthma, 5.9% current asthma, and 12.2% allergy to pollen/pets. Wheeze was reported by 7.8%, 4.5% reported daytime breathlessness, and 2.0% nocturnal breathlessness. Measurements were performed in 23 classrooms (May-June), 74% had <1000 ppm CO(2) indoors. None had visible mold growth or dampness. Mean total microbial volatile organic compound (MVOC) concentration was 423 ng/m(3) indoors and 123 ng/m(3) outdoors. Indoor concentration of TMPD-MIB (2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, Texanol) and TMPD-DIB (2,2,4-trimethyl-1,3-pentanediol diisobutyrate, TXIB), two common plasticizers, were 0.89 and 1.64 microg/m(3), respectively. MVOC and plasticizer concentration were correlated (r = 0.5; P < 0.01). Mold concentration was 360 cfu/m(3) indoors and 980 cfu/m(3) outdoors. At higher indoor concentrations of total MVOC, nocturnal breathlessness (P < 0.01) and doctor-diagnosed asthma (P < 0.05) were more common. Moreover, there were positive associations between nocturnal breathlessness and 3-methylfuran (P < 0.01), 3-methyl-1-butanol (P < 0.05), dimethyldisulfide (P < 0.01), 2-heptanone (P < 0.01), 1-octen-3-ol (P < 0.05), 3-octanone (P < 0.05), TMPD-MIB (P < 0.05), and TMPD-DIB (P < 0.01). TMPD-DIB was positively associated with wheeze (P < 0.05), daytime breathlessness (P < 0.05), doctor-diagnosed asthma (P < 0.05), and current asthma (P < 0.05). In conclusion, exposure to MVOC and plasticizers at school may be a risk factor for asthmatic symptoms in children. PRACTICAL IMPLICATIONS: Despite generally good ventilation and lack of visible signs of mold growth, we found an association between respiratory symptoms and indoor MVOC concentration. In addition, we found associations between asthmatic symptoms and two common plasticizers. The highest levels of MVOC, TMPD-MIB, and TMPD-DIB were found in two new buildings, suggesting that material emissions should be better controlled. As MVOC and plasticizers concentrations were positively correlated, while indoor viable molds and bacteria were negatively correlated, it is unclear if indoor MVOC is an indicator of microbial exposure. Further studies focusing on health effects of chemical emissions from indoor plastic materials, including PVC-floor coatings, are needed.     

Identification and transport investigation of microbial volatile organic compounds in full-scale stud cavities

An experimental project was conducted to investigate mold products, namely spores and volatile organic compounds (VOCs) in the cavity of full-scale stud wall assemblies. Twenty specimens were constructed and tested to inquire the capacity of wall cavities to restrain mold products, emanating from studs with 10% of their surface covered with mold, from penetrating into the indoor space. The tests were designed primarily to study the movement of spores. The project was subsequently extended to investigate the identification of microbial volatile organic compounds (MVOCs) and their transport through the building envelope. This paper presents the experimental design, testing procedure and a summary of the analysis conducted to identify mold related VOCs and their transport from the cavity to the indoor space, and the evaluation of the influence of experimental factors on this transport. Six experimental factors were investigated: air leakage path; mold presence; wall construction configurations (insulation, vapor barrier and sheathing material) and ambient conditions (dry and wet conditions). The chemical analysis of VOCs (volatile organic compounds) was performed using gas chromatography/mass spectrometry (GC/MS). Results are analyzed using multiple regression analysis to identify the mold related VOCs, and to determine the transport through the building envelope. Five VOCs are confirmed to be related to the mold presence in the cavity and the transport of these MVOCs is supported by the data. However, no significant effect of the construction factors on MVOC transport is detected.     

Development of New Volatile Organic Compound (VOC) Exposure Metrics and their Relationship to “Sick Building Syndrome” Symptoms

Abstract Occupants of office buildings are exposed to low concentrations of complex mixtures of volatile organic compounds (VOCs) that encompass a number of chemical classes and a broad range of irritancies. “Sick building syndrome” (SBS) is suspected to be related to these exposures. Using data from 22 office areas in 12 California buildings, seven VOC exposure metrics were developed and their ability to predict self-reported SBS irritant symptoms of office workers was tested. The VOC metrics were each evaluated in a multivariate logistic regression analysis model adjusted for other risk factors or confounders. Total VOCs and most of the other metrics were not statistically significant predictors of symptoms in crude or adjusted analyses. Two metrics were developed using principal components (PC) analysis on subsets of the 39 VOCs. The Irritancy/PC metric was the most statistically significant predictor of adjusted irritant symptoms. The irritant potencies of individual compounds, highly correlated nature of indoor VOC mixtures, and probable presence of potent, but unmeasured, VOCs were variously factored into this metric. These results, which for the first time show a link between low level VOC exposures from specific types of indoor sources to SBS symptoms, require confirmation using data sets from other buildings.     

Microbial volatile organic compounds in the air of moldy and mold-free indoor environments

A single-blinded study was performed to analyze whether indoor environments with and without mold infestation differ significantly in microbial volatile organic compounds (MVOC) concentrations. Air sampling for MVOC was performed in 40 dwellings with evident mold damage and in 44 dwellings, where mold damage was excluded after a thorough investigation. The characteristics of the dwellings, climatic parameters, airborne particles and air exchange rates (AER) were recorded. The parameters mold status, characteristics of the interiors and measured climatic parameters were included in the multiple regression model. The results show no significant association between most of the analyzed MVOC and the mold status. Only the compounds 2-methyl-1-butanol and 1-octen-3-ol indicated a statistically significant, but weak association with the mold status. However, the concentrations of the so-called MVOC were mainly influenced by other indoor factors. 2-Methylfuran and 3-methylfuran, often used as main indicators for mold damage, had a highly significant correlation with the smoking status. These compounds were also significantly correlated with the humidity and the AER. The compounds 3-methyl-1-butanol, 2-hexanone, 3-heptanone and dimethyl disulfide were weakly correlated with the recorded parameters, the humidity being the strongest influencing factor. Only 2-methyl-1-butanol and 1-octen-3-ol showed a statistically significant association with the mold status; however, only a small portion (10% in this case) of the total variability could be explained by the predictor mold status; they do not qualify as indicator compounds, because such minor correlations lead to a too excessive part of incorrect classifications, meaning that the diagnostic sensitivity and specificity of these compounds are too low. PRACTICAL IMPLICATIONS: The assumption that mold infestations might be detected by microbial VOC emissions must be considered with great reservation. The major part of the total variability of the measured MVOC concentrations originates from not known influencing factors and/or from factors not directly associated with the mold status of the dwellings (confounders). More specific and sensitive markers for the assessment of the mold status should be found, if the screening for mold infestations should be performed by volatile organic compounds.     

Investigation of volatile organic compounds in office buildings in Bangkok,Thailand: Concentrations,sources, and occupant symptoms

To conserve energy, office buildings with air-conditioning systems in Thailand are operated with a tight thermal envelope. This leads to low fresh-air ventilation rates and is thought to be partly responsible for the sick building syndrome symptoms reported by occupants. The objectives of this study are to measure concentrations and to determine sources of 13 volatile organic compounds (VOCs) in office buildings with air-conditioning systems in the business area of Bangkok. Indoor and outdoor air samples from 17 buildings were collected on Tenax-TA^™ sorbent tubes and analyzed for individual VOCs by thermal desorption-gas chromatography/mass spectrometry (TD–GC/MS). Building ventilation was measured with a constant injection technique using hexafluorobenzene as a tracer gas. The results show that the VOC concentrations varied significantly among the studied buildings. The two most dominant VOCs were toluene and limonene with average concentrations of 110 and 60.5 μg m⁻³, respectively. A Wilcoxon sum rank test indicated that the indoor concentrations of aromatic compounds and limonene were statistically higher than outdoor concentrations at the 0.05 level, while the indoor concentrations of chlorinated compounds were not. Indoor emission factors of toluene and limonene were found to be highest with the average values of 80.9 and 18.9 μg m⁻² h⁻¹, respectively. Principal component analysis was applied to the emission factors of 13 VOCs, producing three components based on source similarities. Furthermore, a questionnaire survey investigation and field measurements of building air exchange pointed to indoor air complaints related to inadequate ventilation.     

A case of indoor air pollution of ammonia emitted from concrete in a newly built office in Beijing

A case of suspected indoor ammonia contamination from concrete was investigated in an airline company office in Beijing. A standardized questionnaire on indoor environment perceptions, medical symptoms and psychosocial work environment was distributed to all staff, and compared with a reference group of office workers from the same company in Stockholm. Temperature, relative humidity, formaldehyde, volatile organic compounds (VOC), ammonia, and carbon dioxide were measured both in Beijing and Stockholm. In Beijing mould and bacteria were also measured. Totally 95% (N = 14) participated. The Beijing staff reported a higher rate of complaints regarding poor work satisfaction, and work stress as compared to the Stockholm reference group. In the total material (N = 203) the psychosocial environment was related to general symptoms (headache and tiredness) but not odour perception or mucous membrane symptoms. Controlling for age, smoking habits, and psychosocial work environment the Beijing staff had more complaints on unpleasant odour and mucous membrane symptoms. An increased indoor concentration of ammonia (3–6 ppm) and benzene (26.8 μg/m³) was measured in the indoor air in the Beijing office, as compared to the office in Stockholm (<0.1 ppm ammonia and 0.4 μg/m³ benzene). The ammonia contamination in the Beijing office was confirmed, the probable source being additives in the concrete. The ammonia level was well below the Swedish threshold limit values (TLV) (25 ppm). In addition the exposure to benzene, an indicator of traffic exhaust pollution was high both indoors and outdoors in Beijing, possible related to increased levels of odour complaints and mucous membrane irritation.     

Onset of mucosal, dermal, and general symptoms in relation to biomarkers and exposures in the dwelling: a cohort study from 1992 to 2002

We examined the associations between biomarkers of allergy and inflammation, indoor environment in dwellings, and incidence and remission of symptoms included in the sick building syndrome (SBS) and changes in the home environment of 452 adults who were followed from 1992 to 2002 within the Uppsala part of the European Community Respiratory Health Survey (ECRHS). The 10-year incidence (onset) of general, mucosal, and dermal symptoms was 8.5%, 12.7%, and 6.8%, respectively. Dampness or indoor molds at baseline was a predictor of incidence of general (relative risk [RR] = 1.98), mucosal (RR = 2.28), and dermal symptoms (RR = 1.91). Women had higher incidence of general (RR = 1.74) and mucosal symptoms (RR = 1.71). Indoor painting increased the incidence of general symptoms (RR = 1.62). Bronchial responsiveness (BR), eosinophil counts in blood, total IgE and eosinophilic cationic protein (ECP) in serum at baseline were predictors of incidence of SBS. At follow-up, BR, total IgE, and C-reactive protein (CRP ) were associated with increased incidence of SBS. Moreover, subjects with doctor-diagnosed asthma at baseline had a higher incidence of general (RR = 1.65) and mucosal symptoms (RR = 1.97). In conclusion, female gender, dampness or indoor molds, indoor painting, and biomarkers of allergy and inflammation were associated with a higher incidence of SBS symptoms, in particular mucosal symptoms. PRACTICAL IMPLICATIONS: The focus in Sweden on indoor environment issues over the last few decades has resulted in improvements in dwellings, and reduced tobacco smoking, which could be beneficial for public health. Reducing dampness and molds in the dwelling place is another important way of reducing occurrence of SBS symptoms in the general adult population. The association between the incidence of SBS symptoms and clinical biomarkers of allergy and inflammation suggests a common etiology between inflammatory diseases, including asthma, rhinitis, and SBS. Lastly, good agreement between self-reported and clinically diagnosed atopy indicates that questionnaire data on atopy can be used in epidemiological studies.     

Source apportionment of human personal exposure to volatile organic compounds in homes, offices and outdoors by chemical mass balance and genetic algorithm receptor models

A number of past studies have shown the prevalence of a considerable amount of volatile organic compounds (VOCs) in workplace, home and outdoor microenvironments. The quantification of an individual's personal exposure to VOCs in each of these microenvironments is an essential task to recognize the health risks. In this paper, such a study of source apportionment of the human exposure to VOCs in homes, offices, and outdoors has been presented. Air samples, analysed for 25 organic compounds and sampled during one week in homes, offices, outdoors and close to persons, at seven locations in the city of Leipzig, have been utilized to recognize the concentration pattern of VOCs using the chemical mass balance (CMB) receptor model. In result, the largest contribution of VOCs to the personal exposure is from homes in the range of 42 to 73%, followed by outdoors, 18 to 34%, and the offices, 2 to 38% with the corresponding concentration ranges of 35 to 80 microg m(- 3), 10 to 45 microg m(- 3) and 1 to 30 microg m(- 3) respectively. The species such as benzene, dodecane, decane, methyl-cyclopentane, triethyltoluene and trichloroethylene dominate outdoors; methyl-cyclohexane, triethyltoluene, nonane, octane, tetraethyltoluene, undecane are highest in the offices; while, from the terpenoid group like 3-carane, limonene, a-pinene, b-pinene and the aromatics toluene and styrene most influence the homes. A genetic algorithm (GA) model has also been applied to carry out the source apportionment. Its results are comparable with that of CMB.     

A Study of Human Reactions to Emissions from Building Materials in Climate Chambers. Part II: VOC Measurements,Mouse Bioassay,and Decipol Evaluation in the 1–2 mg/m3 TVOC Range

Monitoring of human reactions to the emission of formaldehyde and volatile organic compounds (VOC) from four commonly used building materials was carried out. The building materials were: a painted gypsum board, a rubber floor, a nylon carpet, and a particle board with an acid-curing paint. The exposures were performed in climate chambers. The air quality was quantified on the decipol scale by a trained panel, measurements of formaldehyde and VOC being performed simultaneously. The irritating potency of the materials was measured by a mouse bioassay. The VOC measurements showed several malodorants and irritants. Some abundant VOC identified in the head-space analyses were absent in the climate chamber air. The rubber floor and the nylon carpet exhibited a marked increase in decipols compatible with a number of odorous VOC identified in the air. A high formaldehyde concentration (minimum 743μg/m³) was measured for the particle board coated with an acid-curing paint. This was not reflected by a corresponding relatively high decipol value but a long-lasting irritating potency was observed in the mouse bioassay. TVOC sampled on Tenax and expressed in mass per volume as well as in molar concentration, and decipol evaluation both have limitations and should be used with caution as indicators of (perceived) indoor air quality. Eye irritation expressed by means of the eye index reflecting the tear film quality index (comprised of break-up time, foam formation, thickness of the precorneal lipid layer of the tear film, and epithelial damage) was found to be insensitive to formaldehyde and a VOC mixture but sensitive to TVOC concentrations of 1–2 mg/m³. Lipophilic VOC may be the cause of reduced tear film quality by destabilization of the lipid multilayer of the tear film.