6.6-hour inhalation of ozone concentrations from 60 to 87 parts per billion in healthy humans.

Abstract

Identification of the minimal ozone (O(3)) concentration and/or dose that induces measurable lung function decrements in humans is considered in the risk assessment leading to establishing an appropriate National Ambient Air Quality Standard for O(3) that protects public health. To identify and/or predict the minimal mean O(3) concentration that produces a decrement in FEV(1) and symptoms in healthy individuals completing 6.6-hour exposure protocols. Pulmonary function and subjective symptoms were measured in 31 healthy adults (18-25 yr, male and female, nonsmokers) who completed five 6.6-hour chamber exposures: filtered air and four variable hourly patterns with mean O(3) concentrations of 60, 70, 80, and 87 parts per billion (ppb). Compared with filtered air, statistically significant decrements in FEV(1) and increases in total subjective symptoms scores (P < 0.05) were measured after exposure to mean concentrations of 70, 80, and 87 ppb O(3). The mean percent change in FEV(1) (+/-standard error) at the end of each protocol was 0.80 +/- 0.90, -2.72 +/- 1.48, -5.34 +/- 1.42, -7.02 +/- 1.60, and -11.42 +/- 2.20% for exposure to filtered air and 60, 70, 80, and 87 ppb O(3), respectively. Inhalation of 70 ppb O(3) for 6.6 hours, a concentration below the current 8-hour National Ambient Air Quality Standard of 75 ppb, is sufficient to induce statistically significant decrements in FEV(1) in healthy young adults.