Bronchial responsiveness of non-smoking women exposed to environmental tobacco smoke or biomass fuel combustion.

We studied bronchial responsiveness (BR) in three groups of housewives with or without history of exposure to tobacco smoke or combustion of biomass fuels. Methacholine bronchoprovocation test was used to study BR. The group I subjects (60), who served as controls, were nonsmokers and had no chronic exposure to passive smoking or environmental tobacco smoke (ETS) or biomass fuels. Three of these women showed a 20 per cent FEV1 fall with a cumulative methacholine dose of 72.5 mg or less. Of 60 women in group II (ETS-exposure) and 52 in group III (biomass exposure), 26 (43.3%) and 10 (19.2%) respectively showed bronchial hyper-responsiveness (BHR). The odds ratios for BHR in groups II and III were 14.53 and 4.52 respectively. The number of hyper-responders was significantly more and the mean PD20 less in the exposed than the non-exposed groups. The occurrence of BHR in the ETS exposed group was more (P < 0.05) than the biomass combustion group. There were more hyper-responders (both groups II and III) amongst those who had an exposure index (EI) of 50 or more compared to those with EI of less than 50. We conclude that chronic cumulative exposure to both ETS and biomass combustion produces significant BHR. Further, BHR developed more often on ETS exposure, and when the exposure was present for a longer period.