Aerosol pollution events pose serious threats to humans and ecosystems. Emissions from dust,
fossil fuels and wildfires have increased in many places since preindustrial times globally in both
urban and rural regions. Aerosol particles in these emissions directly alter the radiative budget of
the atmosphere and modify snow and ice surface albedos when deposited on the surface.
Aerosols also indirectly impact climate by modifying cloud properties and changing land and
ocean biogeochemistry. In addition to these impacts, aerosols from dust, fossil fuels and fires
pose major air quality and health concerns. Near-surface particulate matter (PM ) from
aerosols are associated with negative health impacts, including premature mortality. Most
studies have focused on anthropogenic emissions and their impacts on air quality. Natural
aerosols are much less studied for their air quality impacts, even though dust and wildfires have
likely changed because of anthropogenic activities and such changes have the potential to
impact global mortality.
This study seeks to understand how emissions of dust and wildfire aerosols (often referred to as
natural aerosols) have changed over the African continent since the preindustrial era to the
present day and how much they may significantly change in the future under the Coupled Model
Inter comparison Project (CMIP) scenarios. Some studies have shown that global dust mass
loading have increased by 55% since preindustrial times, with North Africa and Asia as the main
drivers, while the frequency and severity of wildfires has decreased significantly in recent
decades, at least globally. The indirect effects of these changes on human health have not yet
been adequately estimated. We will specifically consider the impact of changing aerosols on
premature deaths and outdoor air quality, but do not consider potentially important changes to
indoor air quality.
This current study will use the latest Community Earth System Model (CESM) Community
Atmosphere Model version 6 (CAM6) to simulate estimated preindustrial, present, and future
scenarios of aerosol PM concentrations, including changes in dust and wildfires and apply a
long-term concentration response function from epidemiological studies to estimate which
aerosol sources are most important for changes in African mortality due to exposure. This study
will also assess mortality changes due to differences in PM exposure between people in rural
and urban communities. As most studies on air quality are mainly focused on the urban areas