Response to acute ozone exposure in healthy men. Results of a screening procedure.
We screened 64 healthy, nonsmoking men, 18 to 35 yr old, for their sensitivity to 0.35 ppm ozone (O3) administered for 130 to 150 min with intermittent exercise. The changes in FVC, FEV1, AND FEF25-75 (p < 0.0001) immediately after O3 exposure varied widely among subjects. Histograms of the percentage changes in FVC and FEV1 did not differ from a unimodal, skewed (gamma) distribution (p = 0.99 and p = 0.17, respectively); the changes in FEF25-75 tended to deviate from a gamma distribution (p = 0.055). To adjust FEF25-75 for the confounding effects of O3 on FVC, we used multiple linear regression analysis with contemporaneous FVC as a covariable, analysis of a subgroup of nine subjects whose O3-induced FVC changes were < or = 5%, and volume correction of FEF25-75 for any changes in FVC after exposure. These analyses showed reductions in FEF25-75 unexplained by and following a different time course than the O3-induced changes in FVC. In 26 subjects also exposed to filtered air, significant effects of O3 on respiratory frequency (p < 0.004) and tidal volume (p < 0.0007) correlated weakly with FVC changes. The results confirm the wide variability in spirometric responsiveness among individuals to O3 and suggest that intrinsic narrowing of the small airways may be a significant component of the functional response.
Weinmann
G G
GG
Department of Environmental Health Sciences, Johns Hopkins School of Hygiene and Public Health, Baltimore, Maryland 21205.
Bowes
S M
SM
Gerbase
M W
MW
Kimball
A W
AW
Frank
R
R
D000293:Adolescent; D000328:Adult; D001273:Atmosphere Exposure Chambers; D015444:Exercise / Q000502:physiology; D005541:Forced Expiratory Volume / Q000187:drug effects; D006801:Humans; D016014:Linear Models; D008297:Male; D008450:Maximal Midexpiratory Flow Rate / Q000187:drug effects; D010126:Ozone / Q000009:adverse effects*; D012016:Reference Values; D015656:Respiratory Mechanics / Q000187:drug effects* / Q000502:physiology; D013147:Spirometry / Q000706:statistics & numerical data; D013997:Time Factors; D014797:Vital Capacity / Q000187:drug effects
D010126:Ozone