Limited exposure of rats to H(2)SO(4) with and without O3.

The purpose of this study was to determine the effects of sulfuric acid (H(2)SO(4)) alone and with ozone (O(3)) on rats. To accomplish this, rats were exposed for 8 hours daily to an atmosphere containing either nebulized H(2)SO(4), H(2)SO(4) plus 0.9 ppm O(3), or 0.9 ppm O(3). The atmosphere in the exposure chambers was maintained at a fairly constant temperature and humidity. Nebulized H(2)SO(4) was delivered uniformly to provide a particle size of about 0.3 micron mass median diameter (MMD) and a mass concentration of 2 mg/m(3). In preliminary experiments, animals exposed to 2 mg/m(3) of H(2)SO(4) daily for 82 days showed very slight morphologic injury to the respiratory tract. In contrast, biological effects were readily demonstrable in rats exposed to H(2)SO(4) plus O(3) or to O(3) alone, possibly with some enhancement of effect in animals exposed to the mixture. The effects observed were characteristic of the response to O(3) alone.