Interaction of peroxyacetyl nitrate and ozone on pulmonary functions

The metabolic and pulmonary function effects were investigated in 10 nonsmoking, young adult men who were exposed for 2 h (20 degrees C (wet-bulb globe temperature) (WBGT] to 4 conditions: (1) filtered air (FA), (2) 0.30 ppm peroxyacetyl nitrate (PAN), (3) 0.45 ppm ozone (O3), and (4) 0.45 ppm O3 + 0.30 ppm PAN (PAN/O3). The subjects alternated 15-min periods of rest and 20-min periods of bicycle ergometer exercise at a work load predetermined to elicit a ventilatory minute volume (VE) of 27 L/min (BTPS). Functional residual capacity (FRC) was determined pre- and postexposure. Forced vital capacity (FVC) was determined before and after exposure, and 5 min after each exercise period. Heart rate was monitored throughout the exposure, and (VE), oxygen uptake (VO2), respiratory rate (fR), and tidal volume (VT) were measured during the last 2 min of each exercise period. There were no changes in any variable consequent to FA or PAN exposure. The only metabolic changes to occur because of O3 and PAN/O3 exposure were a decrease in VT, a concomitant increase in fR, and consequently no change in VE. Both O3 and PAN/O3 induced significant (p less than 0.05) decrements in FVC, FEV1.0, FEV2.0, FEV3.0, FEF25-75%, IC, ERV, and TLC. The decrements after PAN/O3 exposure averaged 10% greater than the decrements after O3 exposure. The results suggest an interactive effect between PAN and O3, possibly explained by total oxidant load.