Health effects of subchronic inhalation exposure to simulated downwind coal combustion emissions

Objective: This was the fourth study by the National Environmental Respiratory Center to create a database for responses of animal models to combustion-derived pollutant mixtures, to identify causal pollutants--regardless of source. Methods: F344 and SHR rats and A/J, C57BL/6, and BALB/c mice were exposed 6 h/day 7 days/week for 1 week to 6 months to three concentrations of a mixture simulating key components of downwind coal combustion emissions, to the highest concentration filtered to remove particulate matter (PM), or to clean air. Emissions from low-sulfur subbituminous coal were modified to create a mixture recommended by an expert workshop. Sulfur dioxide, nitrogen oxides, and PM were the dominant components. Nonanimal-derived PM mass concentrations of nominally 0, 100, 300, and 1000 mu A mu g/m