OA-03-518-21 How does exposure to fine particulate matter in Malawi vary by gender, exposure source, and cooking characteristics? Fine-grain data from an ethnography-linked exposure study

Background: Air pollution exposure through the life course contributes to a range of respiratory pathology in adults and children, including acute infections and non-communicable diseases. In Malawi a great majority of the population use solid fuels for cooking, causing frequent exposure to high concentrations of air pollu- tion including fine particulate matter (PM2.5). We use personal air quality data to describe PM2.5 exposures by gender, exposure source and cooking features in a Malawian village.

Design/Methods: Reported exposure data comprise a preliminary analysis of data from a mixed methods study of air pollution in rural Malawi. Researchers spent extended periods of time over seven months alongside men and women living in the village. Portable moni- tors worn during a range of activities captured real-time PM2.5 data (μg/m3) on cooking and other exposures. The resulting 203 hours of data and 6 104 datapoints were analysed in Stata V15.1 using appropriate statisti- cal methods.

Results: Thirty-one exposure intervals were included for female participants; fourteen paired with a male counterpart. For women, median [IQR] PM2.5 levels differed significantly between cooking 418.8 [143.3- 926.7], other exposures 106.6 [57.4-369.2] and baseline (no identified source) 35.2 [21.7-50.7], p=0.001. Paired male data revealed similar median PM2.5 levels to their female counterparts at baseline (39.7 [21.7-47.2]), but without the large cooking-related increases experienced by women: median 46.5 [32.3-70.7] and 38.8 [32.4-51.1] while women cooking and performing other activities respectively.

Biomass was used for all cooking activity. Mixed model regression analysis adjusting for activity, fuel, cooking device, and location showed that lowest cooking related PM2.5 levels were associated with use of cookstoves in well ventilated spaces (typically an unwalled veranda). Conclusions: Cooking constituted the main PM2.5 ex- posure source in this setting. The subsequent gender disparity in exposures is a key finding. Data on variables influencing exposure levels will inform a village-based clean air intervention.