Impacts of Improved Cookstove Interventions on Personal Exposure to Carbon Monoxide and Particulate Matter in Zambia

Eighty‐four percent of sub‐Saharan African households rely on polluting fuels (e.g., wood, charcoal) for cooking, leading to high levels of household air pollution (HAP). While switching to modern fuels/stoves could decrease HAP levels, they are not always available or affordable. Improved biomass cookstoves could provide an intermediate step supporting transitions from traditional biomass to clean burning fuels/stoves. We conducted two stove intervention trials in Lusaka, Zambia using targeted marketing/incentives to motivate participants to use improved biomass stoves, either the Mimi Moto (pellet) or the EcoZoom (charcoal). Before the intervention, 65% of participants exclusively used charcoal, while 27% relied on electricity to some extent for cooking. We measured 24‐hr personal exposure to CO ( n  = 747) and PM 2.5 ( n  = 90) of primary cooks. We implemented several statistical approaches to estimate the effects of interventions on exposure: household‐specific endline minus baseline exposure, ranksum testing, difference‐in‐differences analyses, and cross‐sectional analyses. We found that switching from traditional charcoal stoves to either intervention stove was not associated with significantly reduced exposures. However, cooks using electric stoves independent of the intervention did have significantly lower CO exposures than those using traditional charcoal, with greater electric stove use corresponding to greater exposure reductions. Variability in exposure was dominated by seasonal, regional, and neighborhood differences rather than household stove/fuel choices. A focus on HAP exposure from cooking in urban settings is unlikely to yield expected exposure reductions. Policy makers should consider pollution reduction policies/interventions that target ambient air quality in tandem with HAP‐mitigating strategies to address air pollution health burden. Plain Language Summary In 2019, almost 7 million deaths worldwide were linked to air pollution. In sub‐Saharan Africa, 84% of households use polluting fuels like wood and charcoal for cooking, which leads to high levels of air pollution. While cleaner energy options such as electricity could reduce pollution, they are often not accessible or affordable. Improved biomass cookstoves might offer an intermediate solution, helping people transition from traditional fuels to cleaner options. We conducted two studies in Lusaka, Zambia to encourage traditional stove users to switch to improved biomass stoves, either the Mimi Moto (using wood pellets) or EcoZoom (using charcoal). We measured exposure to carbon monoxide and particulate matter among household cooks. We found that switching to improved stoves did not significantly reduce exposures compared to traditional charcoal use. However, cooks using electric stoves did have lower exposures, with greater exposure reductions as more meals were cooked with electricity. Factors such as season and neighborhood also had substantial impacts on exposure. This suggests that focusing only on reducing pollution from cooking in urban areas may not be enough to improve health. Policymakers should consider broader strategies that also target outdoor air quality to effectively address the health risks of air pollution. Key Points In two interventions, the use of improved biomass stoves was not associated with reduced personal exposures Household cooks using existing electric stoves did have significantly lower exposures than traditional charcoal users Changes in exposure were dominated by seasonal, regional, and neighborhood differences rather than household stove/fuel choices