Acute exposure to biomass smoke causes oxygen desaturation in adult women.

Long-term exposure to biomass fuel smoke indoors is causally associated with chronic obstructive pulmonary disease (COPD) but the effect of acute exposures has not been studied. Should acute effects occur, this might increase the risk of an exacerbation of pre-existing lung disease. We studied acute changes in lung function and oxygen saturation in individuals exposed regularly to biomass smoke in Nepal. Spirometry (EasyOne spirometer using AmericanThoracic Society (ATS) criteria) and oxygen saturation data were collected from 26, randomly selected, life-long non-smoking women (mean6SD age 38.0611.7 years) before and after cooking (morning or evening). Smoke concentrations were measured using a DustTrak (TSI, Shoreview, Minnesota, USA) during cooking events and expressed as PM2.5 (particulate matter of <2.5 mm in diameter). Geometric mean (range) PM2.5 exposures were 2742 (1951e3853) mg/m for a mean 6SD period of 164634 min. Spirometry results are presented in table 1. Taking the best values, group mean forced expiratory volume in 1 s (FEV1) was 1.95 litres (77% predicted), group mean forced vital capacity (FVC) was 2.44 litres (84% predicted) and group mean FEF25e75 (forced expiratory flow between 25% and 75% of FVC) 2.19 l/s (60% predicted). Three (12.5%) women had COPD (2 severe and 1 moderate, GOLD (Global Initiative on Obstructive Lung Disease classification), 8 (33%) had a restrictive defect ranging from mild to severe and 9 (37.5%) had small airways disease. When rested after cooking FEV1 and FEF25e75 fell but not significantly (FEV1: morning p1⁄40.264 and evening p1⁄40.421; FEF25e75 morning p1⁄40.142 and evening p1⁄41.000)) when re-tested after cooking. All subjects had normal SaO2 (arterial oxygen saturation) values before cooking but values fell significantly after cooking (mean difference before and after cooking in the morning, 1.56%, 95% CI 0.94 to 2.18 (p<0.001) and in the evening, 1.53%, 95% CI 0.76 to 2.30 (p1⁄40.001)). Heart rate fell significantly after the morning cooking period ( 5.469.7, 95% CI 10.3 to 0.6, p1⁄40.029) but not during the evening