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Epidemiologic studies have consistently reported increased daily mortality and hospital admissions for ischemic heart disease related to daily changes in ambient particulate levels. One theory is that substances adhering to particulates might have a cardiovascular effect. Styrene has been found in very low doses in air and has chemical characteristics that would cause adherence to particles. Industrial studies have found an increase in cardiovascular disease among styrene-exposed workers. To explore a possible dose-response relation between styrene exposure and ischemic heart disease, the authors of this case-cohort study included 498 cases that died from ischemic heart disease and a 15% random sample (n = 997) of all male workers who were employed during 1943-1984 in two styrene-butadiene rubber-manufacturing plants in the United States. Proportional hazards models showed that recent styrene exposure was significantly associated with acute ischemic heart disease death among active workers. The relative hazard of death from acute ischemic heart disease for exposure during the most recent 2 years among active workers with 2 or more years of employment was 2.95 (95% confidence interval: 1.02, 8.57) at a time-weighted styrene concentration of 0.2-<0.3 ppm and 4.30 (95% confidence interval: 1.56, 11.84) at ≥0.3 ppm for the same exposure period, respectively. [ABSTRACT FROM AUTHOR]

The authors investigated the effect of charcoal smoke exposure on risks of acute upper and lower respiratory infection (AURI and ALRI) among children under age 18 months in Santo Domingo, Dominican Republic (1991–1992). Children living in households using charcoal for cooking (exposed, n = 201) were age-matched to children living in households using propane gas (nonexposed, n = 214) and were followed for 1 year or until 2 years of age. Fuel use and new episodes of AURI and ALRI were ascertained biweekly through interviews and medical examinations. Household indoor-air concentration of respirable particulate matter (RPM) was measured in a sample of follow-up visits. Incidences of AURI and ALRI were 4.4 and 1.4 episodes/child-year, respectively. After adjustment for other risk factors, exposed children had no significant increase in risk of AURI but were 1.56 times (95% confidence interval: 1.23, 1.97) more likely to develop ALRI. RPM concentrations were higher in charcoal-using households (27.9 μg/m3 vs. 17.6 μg/m3), and ALRI risk increased with RPM exposure (10-μg/m3 increment: odds ratio = 1.17, 95% confidence interval: 1.02, 1.34). Exposure to charcoal smoke increases the risk of ALRI in young children, an effect that is probably mediated by RPM. Reducing charcoal smoke exposure may lower the burden of ALRI among children in this population. [ABSTRACT FROM AUTHOR]