Effect of nitrogen dioxide, ozone, and peroxyacetyl nitrate on metabolic and pulmonary function.

The metabolic and pulmonary function responses were investigated in 32 non-smoking men and women (8 men and 8 women 18-26 years of age, and 8 men and 8 women 51-76 years of age) who were exposed for 2 hours to each of 8 conditions: 1) filtered air (FA), 2) 0.13 ppm peroxyacetyl nitrate (PAN), 3) 0.45 ppm ozone (O3), 4) 0.60 ppm nitrogen dioxide (NO2), 5) 0.13 ppm PAN + 0.45 ppm O3 (PAN/O3), 6) 0.13 ppm PAN + 0.60 ppm NO2 (PAN/NO2), 7) 0.60 ppm NO2 + 0.45 ppm O3 (NO2/O3), and 8) 0.13 ppm PAN + 0.60 ppm NO2 + 0.45 ppm O3 (PAN/NO2/O3). The subjects alternated 20-min periods of rest (n = 3) and cycle ergometer exercise (n = 3) at a work load predetermined to elicit a ventilatory minute volume (VE) of approximately 25 L/min (BTPS). Functional residual capacity (FRC) was determined pre- and post-exposure. Forced vital capacity (FVC) was determined before and after exposure, and 5 min after each exercise period. Heart rate was monitored throughout each exposure, and VE was measured during the last 2 min of each exercise period. Exposure to FA, PAN, NO2, and PAN/NO2 had no effect on any measure of pulmonary or metabolic function. Ozone was primarily responsible for the pulmonary function effects observed. There was no significant difference between the responses to O3 exposure and the responses to the three O3 mixtures, indicating no interactions between the pollutants. The results suggest that women may be somewhat more responsive to O3 exposure than men, and that older people (51-76 years of age) may be less responsive to O3 than younger people (18-26 years of age).