Previously observed (JAPCA 38:28-35, 1988) pulmonary responses of delta FEV1 (-13%), moderate to severe pain upon inspiration, and a doubling of PD100 for methacholine following prolonged moderate exercise at 0.12 ppm O3 were of sufficient magnitude to warrant the assessing of responses at a lower range of concentrations, i.e., 0.08, 0.10 and 0.12 ppm O3. Exposures consisted of six 50-min exercises (VE approximately equals 40 L/min), each followed by 10-min rest; a 35-min lunch break was included. When compared with exposures to 0.00 ppm, substantial pulmonary function decrements, respiratory symptoms and increases in nonspecific airway reactivity were observed at all three O3 concentrations. For example, decreases in FEV1 (P < 0.01) of 7%, 7% and 12% were observed at 0.08, 0.10 and 0.12 ppm O3, respectively. The ratios (P < 0.005) of PD100 observed in 0.00 ppm to that in O3 were 1.56 at 0.08 ppm, 1.89 at 0.10 ppm, and 2.21 at 0.12 ppm O3. It is concluded that exercise representative of a day of moderate to heavy work or play performed during exposures to O3 at levels and pattern often found in ambient air induced clinically meaningful pulmonary responses.

"Presented at the US-Dutch Scientific Symposium, Nijmegen, the Netherlands, May 9-13, 1988." "EPA/600/D-89/246." "PB90-129297." "Bibliography included." Microfiche.