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-hour
personal exposure to CO (n=747) and PM2.5 (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 did not find that switching from traditional
charcoal stoves to either intervention stove was 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.