Effects of exposure to 0.06 ppm ozone on FEV1 in humans:: A secondary analysis of existing data

BACKGROUND: Ozone is a potent photochemical oxidant that produces transient, reversible decrements in the lung function of acutely exposed individuals. A recent study provided previously unavailable clinical data for 30 healthy young adults exposed to O-3 at 0.06 ppm. That study showed significant effects of 0.08 ppm on lung function, confirming the findings of others. However, exposure to 0.06 PPM O-3 was not reported to significantly affect lung function. OBJECTTVES: We conducted this analysis to reevaluate the existing lung function data of the volunteers previously exposed to 0.06 PPM O-3 METHODS: We obtained pre- and postexposure data on forced expiratory volume in 1 see (FEV1) for all subjects who were previously exposed for 6.6 hr to filtered air or to 0.06 ppm or 0.08 ppm O-3. We used standard statistical methods appropriate for paired comparisons to reanalyze FEV1 responses after exposure to 0.06 PPM O-3 relative to filtered air. RESULTS: Controlling for filtered air responses, 24 of the 30 subjects experienced an O-3-induced decrement in FEV1. On average, 0.06 ppm O-3 exposure caused a 2.85% reduction in FEV1 (P 0.002), which was consistent with the predicted FEV1 response from existing models. Although the average response was small, two subjects had > 10% FEV1 decrements. CONCLUSIONS: Exposure to 0.06 ppm O-3 causes a biologically small but highly statistically significant decrease in mean FEV1 responses of young healthy adults.