Atmospheric Pollutants and the Pathogenesis

Abstract

Influenza-infected mice exposed continuously to 20 ppm of sulfur dioxide (SO₂) for seven days after virus exposure developed more pneumonia than virus control mice. Dose-response experiments suggested that the post virus SO₂-induced increase in influenzal pneumonia began at about 7 to 10 ppm. The increase in pneumonia was not influenced by altering the virus dosage within a 5 to 100 mouse infectious dose range. A similar increase (15% to 20%) in influenzal pneumonia was observed when mice were exposed to 25 ppm of SO₂ prior to initiation of virus infection. The SO₂ exposure had no effect on the growth of influenza virus in the lungs of mice. Rather, the increase in She amount of pneumonia was associated with SO₂ concentrations which induced low-grade, inflammatory lesions in the lung.