Effect of 3 hours' passive smoke exposure in the evening on airway tone and responsiveness until next morning

Abstract

To study the effect of environmental tobacco smoke (ETS) exposure in the evening on nocturnal changes in airway tone and responsiveness, 17 subjects with mild asthma (mean +/- SD age, 26 +/- 5 years, FEV1% pred., 89 +/- 14%) were exposed to either ambient air (sham) or ETS (20 ppm CO) for 3 h (7:00 to 10:00 p.m.). Seven subjects had a history of ETS-induced respiratory symptoms. Spirometry was performed 2 h before exposure (5:00 p.m.), every 30 min during exposure, and at 11:00 p.m., 3:00 a.m., and 7:00 a.m. The provocative concentrations of methacholine necessary to decrease FEV1 by 20%, PC20FEV1, were assessed at 5:00 p.m., 11:00 p.m., 3:00 a.m., and 7:00 a.m. Compared with pre-exposure measurements, mean FEV1 values during and after ETS exposure were significantly lower than with sham exposure = 0.013 and 0.026). This effect, however, was due to a significant response in single individuals. The higher bronchial responsiveness after ETS than after sham exceeded one doubling concentration in 4, 5, and 4 patients at 11:00 p.m., 3:00 a.m., and 7:00 a.m., respectively. The opposite effect was observed in 2, 2, and 2 patients, respectively. There was no statistically significant mean effect of ETS on airway responsiveness during night; however, there was significant heterogeneity in individual responses (P = 0.0002). Patients with and without a history of ETS-induced symptoms did not show different responses to experimental ETS exposure. In conclusion, our data suggest that in single adult subjects with mild asthma, acute exposure to ETS in the evening can produce a deterioration of airway tone and responsiveness during the night, with wide interindividual variability in the response.

Environmental tobacco smoke exposure and pulmonary function among adults in NHANES III: impact on the general population and adults with current asthma.

“…Controlled chamber exposure studies support the biologic plausibility of ETSrelated asthma exacerbation. After shortterm exposure of 1-3 hr, many asthmatics experience a decline in FEV 1 (50)(51)(52)(53). Pretreatment with bronchodilators appears to prevent the acute decline in FEV 1 in previously reactive subjects (54).…”

Environmental Tobacco Smoke Exposure and Asthma in Adults

“…Perhaps protection by antioxidants accounts for some of the variability of the ETS-induced responses. Finally, Nowak and colleagues (37) observed that the nocturnal decrease in FEVy was more pronounced after ETS than after sham; this observation may be important for patients with bronchial asthma, for whom one of the Thus, ETS exposure has not yet been confirmed as a hazard for adults with asthma. Given the importance of this issue, there is a strong rationale for additional epidemiologic studies of ETS in the indoor environment.…”

Methacholine PC20 In African Americans And Whites With Asthma With Homozygous Genotypes At ADRB2 Codon 16

“…Previous studies have found that post-pubertal female children with asthma have greater airway hyperresponsiveness compared to males [38,39] though no differences between sexes were found in a recent study in mostly adults [17]. Cigarette smoke exposure can also increase airway hyperresponsiveness in patients with asthma but there is large heterogeneity in effect [40,41]. Thus we may have identified a subgroup of patients with asthma by race, ADRB2 genotype, sex, and smoking history that are at increased risk for having airway hyperresponsiveness.…”