A cross-sectional study of exhaled carbon monoxide as a biomarker of recent household air pollution exposure

Rationale: Household air pollution causes 3.5 million deaths annually. Personal exposure assessments required for examining health associations are expensive and require technical expertize, limiting the quality of research in resource-poor settings. Objectives: To assess the feasibility of exhaled carbon monoxide and its relationship to continuous personal carbon monoxide monitoring and markers of respiratory health in female cooks primarily cooking with biomass fuels in Araihazar, Bangladesh. Methods and measure: For a 24-h period, exhaled carboxyhemoglobin (eCOHb) % saturation was measured before and after each cooking episode while simultaneous 24-h personal carbon monoxide monitoring was conducted. The Coburn-Forester-Kane (CFK) equation was used to convert continuous personal CO exposures to predicted COHb % saturation. Respiratory symptoms were assessed by St. George's Respiratory Questionnaire, airway inflammation measured by exhaled breath condensate pH, and lung function determined by spirometry. Spearman's correlation was used to examine the relationship between eCOHb and CKF-derived COHb, EBC pH, and lung function variables. eCOHb % saturation was dichotomized around the median and odds ratios calculated for each respiratory symptom. Main results: Measurement of eCOHb % saturation is feasible in a resource-poor setting. eCOHb % saturation responds to cooking episodes and demonstrates consistency when measured at the same time point 24-h later, suggesting that eCOHb may be a sensitive biomarker of recent HAP exposures.