Mucociliary clearance of inhaled particles measured at 2 h after ozone exposure in humans.
Acute exposure of humans to ozone is known to acutely cause pulmonary function decrements, inflammation, and increased permeability of pulmonary epithelium. A single study in humans has also shown that mucociliary transport increases during acute ozone exposure. Because different responses have shown a different time course of recovery after exposure, it was important to examine mucociliary transport at a different time after the cessation of ozone exposure. We exposed 15 healthy male and female nonsmoking subjects, on different occasions, to clean air and 0.4 ppm ozone for 1 h while they exercised continuously. Pulmonary function was measured immediately before and after exposure and 90 min and 24 h after exposure. Between 2 and 5 h after each exposure, retention of inhaled 5-microns mass median aerodynamic diameter 99mTc-labeled Fe2O3 particles was measured. Each subject returned the next day for a final particle retention measurement. Despite significant changes in pulmonary function, there was no difference in mean whole lung retention time of particles between clean air [77.9 +/- 0.8 (SE) min] and ozone (78.0 +/- 0.8 min) exposures, indicating that mucociliary transport is unaffected by ozone exposure when it is measured 2 h after exposure.
Gerrity
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TR
Clinical Research Branch, US Environmental Protection Agency, Research Triangle Park 27711.
Bennett
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WD
Kehrl
H
H
DeWitt
P J
PJ
D000293:Adolescent; D000328:Adult; D000336:Aerosols; D001980:Bronchi / Q000187:drug effects / Q000502:physiology; D005260:Female; D006801:Humans; D008168:Lung / Q000187:drug effects / Q000502:physiology; D008297:Male; D009079:Mucociliary Clearance / Q000187:drug effects* / Q000502:physiology; D010126:Ozone / Q000008:administration & dosage / Q000009:adverse effects*; D010316:Particle Size; D013997:Time Factors; D014132:Trachea / Q000187:drug effects / Q000502:physiology
D000336:Aerosols; D010126:Ozone