Predictors Of Personal Exposure Research Articles

Particle exposures and health effects in peri-urban South India: findings from the CHAI Project

We provide an overview of findings from the Cardiovascular health effects of air pollution in Telangana, India (CHAI) project, a recent effort to investigate health effects of household and ambient particle exposure in a cross-sectional cohort study. We developed a local land use regression model to estimate particle exposure for all households within 28 villages outside the city of Hyderabad using data from a measurement campaign. Mean measured PM2.5 was 34 (sd 3.2) µg/m3 and black carbon (BC) was 2.7 (sd 0.5) µg/m3. Approximately 60% of households reported using biomass as the primary cooking fuel. To integrate across multiple relevant sources of particle exposure in the population, we developed a model of average personal exposure based on personal exposure measurements (n=610, 24 h avg) and participants’ self-reported usual activities and behaviours. Personal exposure to PM2.5 and BC was predicted for all participants in the cohort (n=6000). Personal exposure measurements were not correlated (Rspearman < 0.2) with annual ambient concentration at residence modeled by land-use regression. Predictors of personal exposure in women included cooking activities and household socioeconomic position, while in men predictors were smoking and occupation. We provide an overview of results from epidemiological analyses to estimate the independent effects of ambient particles and primary cooking fuel on carotid intima media thickness, blood pressure, and blood glucose levels. We also present results regarding the association between predicted personal exposure and vascular function measures over a wide exposure range (e.g. mean PM2.5 51 µg/m3 (IQR=9.4) for men, 61 µg/m3 (IQR=12.9) for women). We discuss lessons learned regarding investigating ambient air pollution in settings with high exposure to household air pollution and challenges using more personalized exposures in epidemiological analysis and how findings from CHAI fit within the broader context of air pollution health effects studies in Indian populations.

Relationships between Nitrogen Dioxide Personal Exposure and Ambient Air Monitoring Measurements among Children in Three French Metropolitan Areas: VESTA Study

In epidemiological studies, investigators have routinely used ambient air concentrations, measured by air-quality monitoring networks, to assess exposure of subjects. When there is great spatial variability of ambient air concentrations or when there are specific indoor exposures, this approach may yield substantial exposure misclassification and distort the associations between exposure and the health endpoints of interest. In 3 French metropolitan areas, the cross-sectional relationships between 48 hr of nitrogen dioxide personal exposure of 73 children and the corresponding 48-hr background ambient air concentrations were analyzed. The crude correlation between ambient air concentrations and personal exposures was poor in all cities (r2 = .009 for Grenoble, r2 = .04 for Toulouse, and r2 = .02 for Paris). These correlations were improved when the authors took into account other ambient air or indoor air sources of nitrogen dioxide emissions (the corresponding multiple linear regression, r2, increased to .43 in Grenoble, .50 in Toulouse, and .37 in Paris). The main variables that explained personal exposures were an index of traffic intensity and proximity and use of a gas cooker at home. The results of this study confirm that ambient air-monitoring site measurements are poor predictors of personal exposure. Investigators should carefully characterize the proximity of roads occupied by dense traffic to the home/school as well as indoor sources of nitric oxide emissions; both of these careful characterizations will assist researchers in the prediction of personal exposure in epidemiological studies.

Personal exposure to benzene and the influence of attached and integral garages.

Benzene is an air pollutant that is a recognised human carcinogen. An air quality standard has been established for ambient air in the UK to reduce the population's exposure. It has been estimated that about 70% of benzene emissions to air in the UK come from petrol vehicles. A number of studies, including the Avon Longitudinal Study of Pregnancy and Childhood in the UK, have found that benzene concentrations in homes with attached or integral garages tend to be higher than in those without such garages. The present paper reviews these studies and reports a detailed investigation of five homes with either an attached or an integral garage. Indoor and outdoor locations were monitored using diffusive sampling to determine the average benzene concentration over approximately 28 days each month for 18 consecutive months (June 1998-November 1999). For one of these homes, ten years of data had shown the indoor benzene concentration to be consistently higher than outdoors. Personal exposure monitoring of one adult in this home showed that the benzene concentration in the main bedroom was a better predictor of personal exposure than the concentration outdoors. In the homes where a car was regularly parked in the garage, 18-month average benzene concentrations of up to 101.3 micrograms m-3 were measured in the garage, which is more than six times the ambient air quality standard for benzene (16.25 micrograms m-3 running annual average). Mean benzene values in all cars and most of the garages studied exceeded the benzene standard. Mean benzene concentrations in the room above the garage ranged from 3.7 micrograms m-3 in one home, where the car was rarely parked in the garage, to 39.9 micrograms m-3 in another home where a car with high benzene emissions was parked in the garage for six of the 18 months monitored. The mean benzene concentration in the room above the garage in this latter home was nearly 2.5 times the ambient air standard. The study demonstrates that there is a potential for people to have a higher exposure to benzene as a result of living in a home with an attached or integral garage. An understanding of routes of personal exposure is important to develop effective policies to reduce risks to health.

Development of a Long-Term Personal Radon Monitor

A personal monitor using track etch technology was developed to obtain a more accurate measure of individual exposure to radon. The monitor is housed in a watch casing, and is worn as such; it is waterproof and can be worn continuously. Field testing of the monitor took place at two locations in British Columbia and involved 49 subjects ranging in age from 5–82 years (mean 36.7 years), in 23 dwellings. Monitors were worn for two months. Simultaneously each home was measured with standard REM AT-100 monitors placed in the basement and the main living area. One questionnaire was completed specific to the home, and another was completed by each resident regarding personal activity patterns in the house and elsewhere. It was found that a good correlation between standard and watch monitors was obtained (r2=0.83). The best predictor of personal exposure was based on a time-weighted average, followed by main floor and basement radon levels. The watch monitors were well received by the participants (both adults and children) for continuous wear and indicate potential for use in domestic and occupational settings.

Development of a Long-Term Personal Radon Monitor

A personal monitor using track etch technology was developed to obtain a more accurate measure of individual exposure to radon. The monitor is housed in a watch casing, and is worn as such; it is waterproof and can be worn continuously. Field testing of the monitor took place at two locations in British Columbia and involved 49 subjects ranging in age from 5–82 years (mean 36.7 years), in 23 dwellings. Monitors were worn for two months. Simultaneously each home was measured with standard REM AT-100 monitors placed in the basement and the main living area. One questionnaire was completed specific to the home, and another was completed by each resident regarding personal activity patterns in the house and elsewhere. It was found that a good correlation between standard and watch monitors was obtained (r2=0.83). The best predictor of personal exposure was based on a time-weighted average, followed by main floor and basement radon levels. The watch monitors were well received by the participants (both adults and children) for continuous wear and indicate potential for use in domestic and occupational settings.