title: Ozone exposure increases respiratory epithelial permeability in humans.
abstract: Ozone is a respiratory irritant that has been shown to cause an increase in the permeability of the respiratory epithelium in animals. We used inhaled aerosolized 99mTc-labeled diethylene triamine pentacetic acid (99mTc-DTPA) to investigate whether human respiratory epithelial permeability is similarly affected by exposure to ozone. In a randomized, crossover double-blinded study, 8 healthy, nonsmoking young men were exposed for 2 h to purified air and 0.4 ppm ozone while performing intermittent high intensity treadmill exercise (minute ventilation = 66.8 L/min). SRaw and FVC were measured before and at the end of exposures. Seventy-five minutes after the exposures, the pulmonary clearance of 99mTc-DTPA was measured by sequential posterior lung imaging with a computer-assisted gamma camera. Ozone exposure caused respiratory symptoms in all 8 subjects and was associated with a 14 +/- 2.8% (mean +/- SEM) decrement in FVC (p less than 0.001) and a 71 +/- 22% increase in SRaw (p = 0.04). Compared with the air exposure day, 7 of the 8 subjects showed increased 99mTc-DTPA clearance after the ozone exposure, with the mean value increasing from 0.59 +/- 0.08 to 1.75 +/- 0.43%/min (p = 0.03). These data show that ozone exposure sufficient to produce decrements in the pulmonary function of human subjects also causes an increase in 99mTc-DTPA clearance.
mesh_terms: D000328:Adult; D004848:Epithelium / Q000187:drug effects / Q000502:physiology; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging / Q000187:drug effects* / Q000502:physiology; D008297:Male; D010126:Ozone / Q000009:adverse effects*; D010539:Permeability; D005082:Physical Exertion; D011877:Radionuclide Imaging; D012119:Respiration / Q000187:drug effects*; D014797:Vital Capacity
chemical_list: D010126:Ozone