Determinants of early-life household air pollution exposure (HAP): carbon monoxide (CO) and PM2.5 concentrations in Bukavu, eastern Democratic Republic of Congo (DRC).

Early-life exposure to key pollutants such as carbon monoxide (CO) and PM2.5 is associated with adverse maternal and child health outcomes. However, data on household CO and PM2.5 concentrations in urban African settings remain limited. This sub-study of the MUTOTO (Swahili: 'child') cohort was conducted in Bukavu, eastern Democratic Republic of Congo (DRC). Pregnant women attending Bukavu Referral Hospital were recruited from three municipalities. Demographic, socioeconomic, housing, and behavioural determinants of HAP were assessed by questionnaire. Personal CO and household PM2.5 concentrations were measured over 24 hours using LASCAR EL-USB-CO loggers and PurpleAir Zen sensors (March 2025 - January 2026). A total of 405 households participated. Mean 24-hour concentrations were 5.3 ppm (SD 8.7) for CO and 53.8 μg/m3 (SD 34.2) for PM2.5. Maximum 24-hour household means values were 65.1 ppm (CO) and 244.3 μg/m3 (PM2.5). Cooking more frequently and biomass fuel use were important associated factors of elevated pollutant concentrations. Households in the extreme and high CO exposure groups were more likely to use biomass fuel than those in the low exposure group (87%, 76% and 56%, respectively; p < 0.001). Most kitchens lacked chimneys (96%). Early-life exposure to HAP remains high in urban eastern DRC, driven by biomass fuel combustion and suboptimal housing conditions. These findings highlight the need for integrated interventions, including clean cooking solutions and improved ventilation, to reduce exposure and protect maternal and child health.