Effect of sulfur dioxide(SO₂) exposure on airway is well known but little about the effect of SO₂ exposure on lung parenchyme. This study is to determine if short term exposure to SO₂ in concentration commonly found in industrialized environment cause potentially harmful effect on the lung parenchyme, and to evaluate the exposure time-response relationship between short term exposure to SO₂ and the inflammatory response in mouse lung.

5ppm SO₂ gas was used and 48 mice were grouped into control(10), 30(9), 60(11), and 120 minute exposure(18) group. In each group, bronchoalveolar lavage(BAL) was done immediately after and at 1,2,3 days after exposure. Histological examination was performed in control and 120 minute exposure group.

1) Cell response in bronchoalveolar lavage fluid. In 30 and 60 minute exposure group, compared to the control group, lymphocyte count has significantly increased(p<0.05) at 1 day after exposure but did not differ at 2 days after exposure. In 120 minute exposure group, also compared to the control group, there was significant increase in total cell, macrophage, and lymphocyte count at 1 day after exposure, (p<0.05) which lasted for 2 days but did not significantly differ at 3 days after exposure. 2) Histological findings in 120 minute exposure group. In the airway, mild epithelial cell damage and ciliary loss were noted but there was no evidence of inflammatory cell infiltration. Interstitial inflammatory infiltration was noted at 1 day after exposure, which lasted for 3 days after exposure and there was no evidence of edema or fibrosis in the interstitium

These data indicate potentially noxious effect of SO₂ on the lung parenchyme as well as the airway at exposure level that are regarded as relatively safe, and the duration of injury depends on the exposure time.