Research Reports

In Part III of the National Morbidity, Mortality, and Air Pollution Study (NMMAPS), Dr. Daniels and colleagues at Johns Hopkins University and Harvard University evaluated the shape of the relation between PM₁₀ concentrations measured at fixed monitoring sites and daily mortality among residents from all causes (excluding accidental causes), from all cardiovascular and respiratory causes combined, and from causes other than cardiovascular-respiratory disease.

Dr. Laskin and her colleagues at the Environmental and Occupational Health Sciences Institute at Rutgers University tested the hypothesis that oxidants in ambient air, such as hydrogen peroxide, may be transported by fine particulate matter into the lungs and thus contribute to lung tissue injury. The investigators used ammonium sulfate particles because of their prevalence in the ambient air of the eastern United States and their reportedly low toxicity in animals and humans.

Stephen Holgate and his colleagues at the University of Southampton proposed that inflammatory changes in lung fluids and blood from humans exposed to PM were related to the chemical composition of the particles. He obtained samples from two human studies in which participants were exposed to diesel exhaust and concentrated ambient particles (CAPs). At a Swedish laboratory 25 healthy and 12 asthmatic participants were exposed to diesel exhaust or filtered air on separate days. At a US laboratory, 12 healthy participants were exposed to filtered air and 30 different healthy participants were exposed to a range of CAPs concentrations. All participants underwent bronchoscopy to obtain lung tissues and fluids to analyze inflammatory markers, including numbers of specific white blood cells, expression of activation markers, and levels of cytokines in addition to analysis of lung function, lung fluids, and blood.

Dr. Albertini and colleges organized a group of researchers from the United States, Czech Republic, The Netherlands, and the United Kingdom to determine whether biomarkers in the blood and urine of workers exposed to butadiene in occupational settings correlated with their personal exposure. Samples were collected from male workers employed either in a plant that used butadiene and styrene to produce rubber polymer in Prague. They also collected blood and urine from male administrative workers at the plant who had no direct occupational exposure to butadiene and served as control subjects.

Drs Turteltaub and Mani at Lawrence Livermore National Laboratory investigated benzene metabolism in rodents over a large dose range that encompassed concentrations close to those of human ambient exposure. Understanding benzene metabolism at low exposure levels is critical to benzene assessment to determine the shape of the dose-response curve at low concentrations.The investigators administered radioactive benzene to mice and rats and subsequently analyzed bone marrow, liver, urine, and plasma from these animals.

Dr. Aust and her colleagues at Utah State University and Ford Motor company hypothesized that transition metals (metals that can participate in possibly toxic oxidative reactions) associated with particulate matter are released within lung epithelial cells and catalyze the formation of reactive oxygen species. The investigators focused their study on coal fly ash that was produced in the laboratory and separated into four size fractions.

Dr. Schlesinger and colleagues at the New York University School of Medicine used a well-established animal model of airway hyperresponsiveness (a heightened tendency of the bronchial airways to constrict) and allergic asthma to determine whether ozone can induce airway hyperresponsiveness or exacerbate existing airway hyperresponsiveness. Male and female guinea pigs were exposed to ozone concentrations comparable to levels to which humans are exposed during periods of ozone pollution.

This report describes two studies that measured emissions in roadway tunnels. Dr. Alan Gertler and colleagues at the Desert Research Institute studied particulate matter emissions in the Tuscarora Mountain Tunnel located on the Pennsylvania Turnpike. Dr Daniel Grosjean and colleague at DGA, Inc studied carbonyl emissions in the Tuscarora Mountain Tunnel and in the Caldecott Tunnel in California. The unique environment in tunnel studies allows the investigators to measure emission rates averaged over many vehicles, to determine the physical and chemical character of emissions under ambient conditions, and in some instances to compare current emissions with past emissions at the same location. Both groups of investigators also measured emissions at times when the proportions of gasoline engine vehicles and diesel engine vehicles differed, allowing them to estimate the differences between emissions from the two sources.