Search for: All records

Long‐term exposure to ambient fine particulate matter (PM_2.5) is the second leading risk factor of premature death in Sub‐Saharan Africa. We use GEOS‐Chem to quantify the effects of (a) trash burning, (b) residential solid‐fuel burning, and (c) open biomass burning (BB) (i.e., landscape fires) on ambient PM_2.5and PM_2.5‐attributable mortality in Africa. Using a series of sensitivity simulations, we excluded each of the three combustion sources in each of five African regions. We estimate that in 2017 emissions from these three combustion sources within Africa increased global ambient PM_2.5by 2%, leading to 203,000 (95% confidence interval: 133,000–259,000) premature mortalities yr⁻¹globally and 167,000 premature mortalities yr⁻¹in Africa. BB contributes more ambient PM_2.5‐related premature mortalities per year (63%) than residential solid‐fuel burning (29%) and trash burning (8%). Open BB in Central Africa leads to the largest number of PM_2.5‐attributed mortalities inside the region, while trash burning in North Africa and residential solid‐fuel burning in West Africa contribute the most regional mortalities for each source. Overall, Africa has a unique ambient air pollution profile because natural sources, such as windblown dust and BB, contribute strongly to ambient PM_2.5levels and PM_2.5‐related mortality. Air pollution policies may need to focus on taking preventative measures tomore »avoid exposure to ambient PM_2.5from these less‐controllable sources.

Biomass burning (BB) is a major source of pollutants that impact local, regional, and global climate, air quality, and public health. However, the influence of burning conditions and fuel type on the emission factors of pollutants is still not well understood. Here, we present the results from a laboratory study of emission factors (EFs) of pollutants from six different sub‐Saharan African biomass fuels combusted under a wide range of burning conditions, ranging from smoldering to flaming. We found that particulate matter (PM) and carbon monoxide (CO) EFs (g (kg wood)⁻¹) are highly sensitive to the burning conditions, with an order of magnitude variation between flaming and smoldering burning conditions. Nitric oxide (NO) EF shows a fuel type dependence, with higher NO EFs for fuels with larger nitrogen content. While CO is not generally a proxy for PM_2.5emissions, in this work a correlation was found between CO and PM emissions generated by combustion of seven wood fuels with moisture content (dry basis) <10% in a tube furnace and measured from a laboratory smog chamber with a temperature of ∼21–24°C and an RH below 5%. Unlike total PM, EFs of inorganic particle‐phase species do not show dependence on burning conditions. Finally, wemore »showed that burning biomass fuels in a tube furnace would be a useful experimental approach to study BB emission under controlled burning conditions.