Kanawha County, West Virginia, is one of the largest chemical manufacturing centers in the United States. In 1988, a survey of respiratory and irritant symptoms was administered to all third grade to fifth grade children attending 74 elementary schools in Kanawha County, and concentrations of 15 volatile organic compounds were measured at each school. Exposures were characterized by school location, by the sum of the concentrations of five petroleum-related compounds, and by the sum of the concentrations of 10 compounds more specific to industrial processes. Children enrolled in schools within the valley had higher rates of doctor-diagnosed asthma (odds ratio (OR) = 1.27, 95% confidence interval (CI) 1.09-1.48) and a higher score on a composite indicator of five chronic lower respiratory symptoms (OR = 1.13, 95% CI 1.02-1.26) than children who were enrolled in schools outside of the valley. The incidence of chronic respiratory symptoms was also positively associated with the concentrations of volatile organic compounds. The estimated change in the odds ratio for chronic lower respiratory symptoms associated with a 2-micrograms/m3 change in process-related compounds was 1.08 (95% CI 1.02-1.14). No consistent pattern was found between acute irritant symptoms in the 2 weeks preceding questionnaire administration and either proximity to industry or exposure to volatile organic compounds. The authors conclude that exposure to volatile organic compounds, including emissions from chemical manufacturing plants, is associated with increased rates of chronic respiratory symptoms characteristic of reactive airways.
A large scale study of human exposure to nitrogen dioxide (NO2) was conducted in the Los Angeles Basin, the only metropolitan area in the United States that exceeds the NO2 NAAQS. Data are available for a population representative sample of 482 households and 682 individuals. Personal exposures, as well as indoor and outdoor home levels, were monitored using passive time-integrating filter badges. Monitoring extended over a one-year period (May 1987 to May 1988), with each individual providing two consecutive days of data. Information was also collected on activity patterns, household and personal characteristics, and spatial and temporal variables. This paper describes the study design, summarizes the sample characteristics and representativeness, and presents the distribution of personal, indoor, and outdoor NO2 concentrations recorded by the monitors. Over the entire sample, median personal and outdoor levels were 35 ppb; median indoor levels were 24 ppb. Personal exposures for those in homes with gas ranges with pilot lights average 10 ppb greater than those with electric ranges, and 4 ppb greater than those with gas ranges without pilot lights. Forty percent of the variation in indoor concentrations is explained by outdoor levels; 59 percent of the variation in personal exposures is explained by indoor levels; and 48 percent of the variation in personal exposures is explained by outdoor levels.
Nitrogen dioxide is an oxidant gas that contaminates outdoor air and indoor air in homes with unvented gas appliances. A prospective cohort study was carried out to test the hypothesis that residential exposure to NO2 increases incidence and severity of respiratory illnesses during the first 18 months of life. A cohort of 1,205 healthy infants from homes without smokers was enrolled. The daily occurrence of respiratory symptoms and illnesses was reported by the mothers every 2 wk. Illnesses with wheezing or wet cough were classified as lower respiratory tract. Indoor NO2 concentrations were serially measured with passive samplers place in the subjects' bedrooms. In stratified analyses, illness incidence rates did not consistently increase with exposure to NO2 or stove type. In multivariate analyses that adjusted for potential confounding factors, odds ratios were not significantly elevated for current or lagged NO2 exposures, or stove type. Illness duration, a measure of illness severity, was not associated with NO2 exposure. The findings can be extended to homes with gas stoves in regions of the United States where the outdoor air is not heavily polluted by NO2.
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