Air pollution is associated with increased level of exhaled nitric oxide in nonsmoking healthy subjects

The authors sought to determine which air pollutant is responsible for the increase in exhaled nitric oxide observed in healthy subjects. Exhaled nitr ic oxide was measured in 16 nonsmoking healthy subjects on 14 workdays, dur ing which there were varying air-pollution levels. Contamination of samples by ambient nitric oxide was excluded. The baseline value of exhaled nitric oxide, determined at times when outdoor air pollution was low, ranged from 7 to 43 ppb (mean = 28 +/- 5 ppb). The daily value of exhaled nitric oxide (range = 5-60 ppb) was associated positively with ambient carbon monoxide (r = .85) and nitric oxide (r = .81). Exposure during the morning hours to high levels of outdoor pollution was associated with increased exhaled nitr ic oxide (i.e., 50% above baseline), which persisted for up to 5 h (i.e., 3 2% above baseline). These results indicated that exhaled nitric oxide level s represent a useful biomonitor of individual exposure to air pollutants.