Nitrogen Oxides

This report addressed the hypothesis that exposure to oxidant air pollutants enhances susceptibility to viral infection. Drs. Kulle and Clements exposed healthy human volunteers who were seronegative to cold-adapted influenza A virus to clean air or nitrogen dioxide concentrations of 1, 2, or 3 ppm for two hours a day for three consecutive days. Live influenza A virus was administered intranasally to all participants after the second day of exposure.

Addressing the need for better assessment of human exposure to mobile source emissions, this report investigates proteinase inhibitor activity as a potential biomarker of oxidant exposure. In this study by Dr. Johnson, human participants were exposed to 0.5 ppm ozone for four hours on consecutive days and to concentrations ranging from 0.6-2 ppm nitrogen dioxide for three hours. Blood samples were obtained and the functional activity of the proteinase inhibitors, alpha-1-proteinase, and bronchial leukocyte proteinase was assessed.

Previous research has reported that the lung development of animals exposed to oxidant gases early in life might be impaired, or that developing lungs might be more susceptible than adult lungs to inhaled toxicants. Dr. Mauderly and colleagues at the Lovelace Biomedical and Environmental Research Institute examined the age-related differences in the physiological responses of rats to inhaled automotive emissions. The younger group was exposed during gestation and through the age of six months, while the older group was exposed between the age of six and twelve months.

Acute hemolytic anemia is associated with a deficiency in glucose 6-phosphate dehydrogenase (G6PD), an X-linked inheritable characteristic. Hemolytic anemia is thought to be caused by a depletion of glutathione and other reducing compounds in red blood cells. Dr. Amoruso and colleagues sought to experimentally test the Calabrese hypothesis, which suggests that G6PD-deficient individuals may be at an increased risk of hemolysis during exposure to low levels of oxidants such as ozone.