Over 90% of 91 day care centers in greater Montréal, Québec exceeded 1000 ppm of CO2 during January through April 1989. Four variables were independent positive predictors of CO2 levels: the density of children in the center; presence of electric heating; absence of a ventilation system; and building age. High levels of CO2 are associated with respiratory tract and other symptoms. Clear standards and inspection policies should be established for day care center air quality.
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Exposure to respirable suspended particles (RSP) from all sources and environmental tobacco smoke (ETS) was assessed for 190 nonsmokers in Stockholm during 1994. Each subject wore a personal monitor for 24-h, provided saliva samples for cotinine analysis, and completed a detailed questionnaire about air quality and life-style. The subjects consisted of housewives and househusbands in one main group and working men and women in the second. The housewives and househusbands wore a single monitor throughout the 24-h period and the working subjects wore one monitor at work and a separate monitor while not at work. The geodemographic distribution of the recruited subjects accurately reflected the population of Stockholm. For most of the subjects, exposure to ETS and nicotine was at or below the limits of quantification (LOQ). This finding was supported by the fact that about 80% of the recruited subjects claimed that their exposure to ETS was "none" or "low". The concentration of RSP was found to be highest (median 39 micrograms.m-3) in homes where smoking occurred and below the LOQ in the workplace irrespective of its smoking status. These levels are at the lowest end of typical indoor air levels for RSP. For the housewives and househusbands living in smoking homes (nonsmoking homes in parentheses), the median exposure levels were 39 micrograms.m-3 (18 micrograms.m-3) for RSP, 17 micrograms . m-3 (0.12 micrograms . m-3) for ETS particles, and 1.1 micrograms.m-3 (0.05 micrograms.m-3) for nicotine. Both the pre- and postmonitoring continine saliva levels measured for these housewives and househusbands were 2.9 ng.ml-1 (pre-0.56 ng.ml-1, post-0.41 ng.ml-1). The highest exposure levels were recorded for the housewives and househusbands in the age range of 35-49 years. For the working subjects, the exposure measured in smoking workplaces (nonsmoking workplaces in parentheses) gave median levels of 16 micrograms.m-3 (16 micrograms.m-3) for RSP, 1.1 micrograms.m-3) for ETS particles and 0.2 micrograms.m-3 (0.15 microgram.m-3) for nicotine. Similarly measured exposures at home (nonsmoking homes in parentheses), including all other locations outside the workplace, gave median levels of 24 micrograms.m-3 (19 micrograms.m-3) for RSP, 1.4 micrograms. m-3 (0.2 microgram.m-3) for ETS particles, and 0.15 microgram.m-3 (0.07 microgram.m-3) for nicotine. Overall, the exposure levels of ETS due to living with smokers in Stockholm was found to be much lower than similar exposures measured previously in the United Kingdom and the United States. Over 70% of all the nicotine measurements and 60% of all the ETS measurements were below the LOQ. When the median values for nicotine and ETS particles are converted to cigarette equivalents, Stockholm housewives and househusbands living with smokers would receive 6-9 cigarette equivalents per year, working nonsmokers living with smokers would receive 0.6-0.7 cigarette equivalents at home, and nonsmokers working with smokers would be exposed to 0.1-0.2 cigarette equivalent at work. The exposures were therefore up to six times greater at home than in workplaces where smoking was occurring. Although all the subjects were recruited as nonsmokers on the basis of their self-reported nonsmoking status, saliva continine measurements were used for confirmation. Subjects with continine levels below 25 ng.ml-1 were considered to be nonsmokers although the selection of a threshold level within the range of 10-50 ng.ml-1 was not considered to be critical. With a threshold of 25 ng.ml-1, between 2.7% and 5.3% were later shown to be misclassified as nonsmokers, depending on the definition of misclassification used. During the study period the air quality in Stockholm could be described according a British nomenclature as "very good" for the majority of the time. The daily average at no time fell below "good," and the maximum hourly nitrogen dioxide level was 111 micrograms.m-3 (inner city at street level) on the coldest day
Measurements of gaseous and particulate concentrations are used to characterize the indoor environment, but such measurements may reflect temporary conditions that are not representative of longer time periods. Moreover, indoor air quality (IAQ) measurements are autocorrelated, a result of limited mixing and air exchange, cyclic emissions, HVAC operation, and other factors. This article analyzes the autocorrelation and variability of IAQ measurements using time series analysis techniques in conjunction with a simple IAQ model. Autocorrelations may be estimated using the air exchange rate (alpha) and ventilation effectiveness (epsilon) of the building or room under study, or estimated from pollutant measurements. From this, the variability, required sample size, and other sampling parameters are estimated. The method is tested in a case study in which particle number, fungi, bacteria, and carbon dioxide concentrations were continuously measured in an office building over a 1-week period. The estimated air exchange rate (1.4/hr) for area studied was predicted to yield autocorrelation coefficients of approximately 0.5 for measurements collected on 30-min intervals. Autocorrelation coefficients based on airborne measurements (lag 0.5 hr) ranged from 0.5 to 0.7 for 1-25 microm diameter particles, fungi, and CO2, but near zero for particles
Chlorinated paraffins (CPs) are large production volume chemicals used in a wide variety of commercial applications. They are ubiquitous in the environment and humans. Human exposure via the indoor environment has, however, been barely investigated. In the present study 44 indoor air and six dust samples from apartments in Stockholm, Sweden, were analyzed for CPs, and indoor air concentrations are reported for the first time. The sumCP concentration (short chain CPs (SCCPs) and medium chain CPs (MCCPs)) in air ranged from
Both building materials and consumer products have been identified as possible sources for potentially hazardous substances like phthalates, polychlorinated biphenyls (PCBs), organophosphorous flame retardants (OPFRs), polybrominated diphenyl ethers (PBDEs) and short chain chlorinated paraffins (SCCPs) in indoor air. Thus, indoor air has been suggested to contribute significantly to human exposure to these chemicals. There is lack of data on the occurrence of several of the aforementioned chemicals in indoor air. Therefore, indoor air (gas and particulate phase) was collected from 48 households and 6 classrooms in two counties in Norway. In both the households and schools, median levels of low molecular weight phthalates (785?ng/m3), OPFRs (55?ng/m3) and SCCPs (128?ng/m3) were up to 1000 times higher than the levels of PCBs (829?pg/m3) and PBDEs (167?pg/m3). Median concentrations of dimethyl phthalate (DMP), diethyl phthalate (DEP), di-isobutyl phthalate (DiBP) and SCCPs were 3-6 times higher in households compared to schools. The levels of OPFRs, PCBs and PBDEs were similar in households and schools. In univariate analysis, the indoor concentrations of different environmental chemicals were significantly affected by location of households (OPFRs), airing of living room (some PCBs and PBDEs), presence of upholstered chair/couch (OPFRs), pet animal hold (some PBDEs) and presence of electrical heaters (selected PCBs and PBDEs). Significant correlations were also detected for the total size of households with OPFRs, frequency of vacuuming the living room with selected PCBs and PBDEs, frequency of washing the living room with selected PCBs and the total number of TVs in the households with selected phthalates and SCCPs. Finally, intake estimates indicated that indoor air contributed more or equally to low molecular weight phthalates and SCCPs exposure compared to food consumption, whereas the contribution from indoor air was smaller than the dietary intake for the other groups of chemicals.
Alternative plasticizers to phthalate esters have been used for over a decade, but data regarding emissions, human exposure and health effects are limited. Here we review 20 alternative plasticizers in current use and their human exposure, hazard and risk. Physicochemical properties are collated for these diverse alternatives and log KOW values range over 15 orders of magnitude and log KAW and log KOA values over about 9 orders of magnitude. Most substances are hydrophobic with low volatility and are produced in high volumes for use in multiple applications. There is an increasing trend in the total use of alternative plasticizers in Sweden compared to common phthalate esters in the last 10 years, especially for DINCH. Evaluative indoor fate modeling reveals that most alternatives are distributed to vertical surfaces (e.g. walls or ceilings). Only TXIB and GTA are predicted to be predominantly distributed to indoor air. Human exposure data are lacking and clear evidence for human exposure only exists for DEHT and DINCH, which show increasing trends in body burdens. Human intake rates are collected and compared with limit values with resulting risk ratios below 1 except for infant's exposure to ESBO. PBT properties of the alternatives indicate mostly no reasons for concern, except that TEHPA is estimated to be persistent and TCP toxic. A caveat is that non-standard toxicological endpoint results are not available and, similar to phthalate esters, the alternatives are likely "pseudo-persistent". Key data gaps for more comprehensive risk assessment are identified and include: analytical methods to measure metabolites in biological fluids and tissues, toxicological information regarding non-standard endpoints such as endocrine disruption and a further refined exposure assessment in order to consider high risk groups such as infants, toddlers and children.
Methylcyclopentadienyl manganese tricarbonyl (MMT), is an additive in gasoline, and its combustion leads to the emission of Mn particles, which increase atmospheric metal concentrations. The objective of this study was to determine the level of outdoor and indoor respirable Mn (MnR) in Montreal, Canada, where MMT has been used since 1976. Ten women were involved in this study: five living in an urban area, near an expressway with high traffic density, and five residing in a rural area characterized by low traffic density. Outdoor and indoor air samples were collected each week (5 in total) during 3 consecutive days; blood samples were collected at the end of the air sampling period. The average concentration of outdoor MnR in the urban area was 0.025 microg/m3, which is significantly different from the average of 0.005 microg/m3 found in the rural area. The average indoor MnR concentration was also significantly different from teh average MnR indoor concentrations within both areas. The mean blood Mn concentrations were not significantly different between the urban area (0.017 microg/m3) and the rural area (0.007 microg/m3). The average outdoor MnR concentrations within both areas. The mean blood Mn concentrations were not significantly different between the two groups. Data suggest that a high outdoor atmospheric MnR leads to a high indoor MnR, but not to an increase in blood Mn levels.
Indoor air problems in schools appear to influence learning outcomes and absence rates. However, previous research has not investigated whether indoor air problems influence the social climate of schools. Therefore, we studied whether indoor air problems observed in schools associate with students' perceptions of the teacher-student relationship and class spirit. The nationwide sample of Finnish schools (N=194 schools/27153 students) was analyzed using multilevel structural equation modeling. Data on the schools' social climate collected from students were merged with independently collected data on observed indoor air problems from school principals. We found that the teacher-student relationship was reported to be worse in schools with observed indoor air problems compared to those without observed indoor air problems. Furthermore, the reported class spirit was worse in schools with observed indoor air problems, but only among students with a high grade point average. Our findings indicate that indoor air problems may affect the student-perceived social climate.
Long-term measurements of thoron progeny concentrations (equilibrium-equivalent thoron concentration) have been carried out in Swedish dwellings with the aim of investigating if thoron and its progeny pose a health risk. Measurements were performed in 93 houses and 25 apartments. In addition to thoron progeny concentration, thoron gas concentration near the wall surface, ambient dose equivalent rate of gamma radiation and radon gas concentration were also measured. The results show that the mean value of thoron progeny was 2.2 Bq m(-3) in houses and 1.6 Bq m(-3) in apartments. Ten per cent of the dwellings (both houses and apartments) had thoron progeny concentrations exceeding 10 Bq m(-3). Thoron progeny concentration is not significantly different in dwellings built of alum shale-based aerated concrete ('blue concrete') than dwellings built of other construction materials. For the dwellings in this study (not representative of the Swedish population), the mean dose estimated due to exposure to thoron was found to be 0.4 mSv y(-1).
An extensive study has been conducted on the prevalence of organophosphorous flame retardants/plasticizers and phthalate ester plasticizers in indoor air. The targeted substances were measured in 45 multi-storey apartment buildings in Stockholm, Sweden. The apartment buildings were classified as high or low risk with regard to the reporting of sick building symptoms (SBS) within the project Healthy Sustainable Houses in Stockholm (3H). Air samples were taken from two to four apartments per building (in total 169 apartments) to facilitate comparison within and between buildings. Association with building characteristics has been examined as well as association with specific sources by combining chemical analysis and exploratory uni- and multivariate data analysis. The study contributes to the overall perspective of levels of organophosphate and phthalate ester in indoor air enabling comparison with other studies. The results indicated little or no difference in the concentrations of the target substances between the two risk classifications of the buildings. The differences between the apartments sampled within (intra) buildings were greater than the differences between (inter) buildings. The concentrations measured in air ranged up to 1200 ng m(-3) for organophosphate esters and up to 11?000 ng m(-3) for phthalate esters. Results in terms of sources were discerned e.g. PVC flooring is a major source of benzylbutyl phthalate in indoor air.