Airway responses to nitrogen dioxide in asthmatic subjects.
Nitrogen dioxide is a common indoor air pollutant. In order to characterize the respiratory responses to this gas, 10 asthmatics (mean age +/- SD = 30 +/- 8 yrs) were exposed to air and 0.5 ppm NO2 gas for 1 h in a 30-m3 environmental chamber on different days in a double-blind randomized fashion. The forced vital capacity, (VC), functional residual capacity, forced expiratory volume in 1 s, partial expiratory flow at 40% VC (Vp 40), and specific airway conductance were measured before and after exposure. Airway reactivity to methacholine inhalation was determined after each exposure. The dose of methacholine in milligrams per milliliter to cause a 40% decrease in Vp 40 was measured. None of the subjects reported any significant symptoms after exposure. Significant potentiation of airway reactivity was noted after NO2 exposure in asthmatic subjects as a group [PD40(AIR) = 9.2 +/- SD 15.0 versus PD40(NO2) = 4.6 +/- SD 8.2 mg/ml, p = 0.042]. No significant changes were noted in other lung functions after NO2 exposure. These findings indicate that asthmatics exposed to 0.5 ppm NO2 develop heightened airway reactivity.
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John B. Pierce Foundation Laboratory, New Haven, Connecticut 06519.
D000328:Adult; D000393:Air Pollutants / Q000633:toxicity*; D001249:Asthma / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008168:Lung / Q000187:drug effects / Q000503:physiopathology; D008297:Male; D016210:Methacholine Chloride; D008688:Methacholine Compounds; D008834:Microclimate; D009585:Nitrogen Dioxide / Q000633:toxicity*; D012129:Respiratory Function Tests; D012137:Respiratory System / Q000187:drug effects / Q000503:physiopathology*
D000393:Air Pollutants; D008688:Methacholine Compounds; D016210:Methacholine Chloride; D009585:Nitrogen Dioxide