The effect of exposure to ozone and nitrogen dioxide on the airway response of atopic asthmatics to inhaled allergen: dose- and time-dependent effects.
Eleven mild atopic asthmatic patients were exposed for 6 h, in randomized order, to air, 100 ppb O3, 200 ppb NO2, and 100 ppb O3 + 200 ppb NO2, followed immediately by bronchial allergen challenge. Subsequently 10 of these patients were exposed for 3 h to air, 200 ppb O3, 400 ppb NO2, and 200 ppb O3 + 400 ppb NO2, followed immediately by bronchial allergen challenge. All exposures were carried out in an environmental chamber, with intermittent moderate exercise, and a minimal interval of 2 wk. Exposure for 6 h to 100 ppb O3, 200 ppb NO2, and 100 ppb O3 + 200 ppb NO2 did not lead to any significant increase in the airway response of these individuals to inhaled allergen, when compared with exposure for 6 h to air. In contrast, exposure for 3 h to 200 ppb O3, 400 ppb NO2, and 200 ppb O3 + 400 ppb NO2 significantly decreased the dose of allergen (in log cumulative breath units [CBU]) required to decrease FEV1 by 20% (allergen PD20FEV1), compared with exposure to air (geometric mean CBU: 3.0 for air versus 2.66 for O3 [p = 0.002]; 2.78 for NO2 [p = 0. 018]; 2.65 for O3 + NO2 [p = 0.002]). These results suggest that the pollutant-induced changes in airway response of mild atopic asthmatics to allergen may be dependent on a threshold concentration rather than the total amount of pollutant inhaled over a period of time.
Jenkins
H S
HS
Academic Department of Respiratory Medicine, St. Bartholomew's and the Royal London School of Medicine and Dentistry, London Chest Hospital, London, United Kingdom.
Devalia
J L
JL
Mister
R L
RL
Bevan
A M
AM
Rusznak
C
C
Davies
R J
RJ
D000328:Adult; D000393:Air Pollutants / Q000494:pharmacology*; D000403:Airway Resistance / Q000187:drug effects* / Q000502:physiology; D000485:Allergens; D001249:Asthma / Q000175:diagnosis / Q000503:physiopathology*; D001250:Asthma, Exercise-Induced / Q000175:diagnosis / Q000503:physiopathology; D001985:Bronchial Provocation Tests; D005260:Female; D005541:Forced Expiratory Volume / Q000187:drug effects / Q000502:physiology; D006801:Humans; D007428:Intradermal Tests; D008297:Male; D009585:Nitrogen Dioxide / Q000494:pharmacology*; D010126:Ozone / Q000494:pharmacology*; D012130:Respiratory Hypersensitivity / Q000175:diagnosis / Q000503:physiopathology*; D016037:Single-Blind Method
D000393:Air Pollutants; D000485:Allergens; D010126:Ozone; D009585:Nitrogen Dioxide