Investigating the Trend and Evolution of PM 2.5 Concentrations in Some West and Central African Countries Using the Clarity Low-Cost Sensors.

There is a dearth of atmospheric data, especially air quality data, across Africa. This is due to several factors including high cost of installation and maintenance, and lack of appropriate regulatory and monitoring policies. This limits, among other things, the ability to evaluate satellite-based measurements, global and regional chemical models. In these regions of the world, the numbers of citizens prematurely dying from poor air quality and those suffering from serious illnesses due to exposure of poor outdoor air quality are estimated to be significant and yet air quality measurements remain sparse. In 2020, an international collaborative team began a campaign to densify air quality monitoring in the West and Central African region. In this study, the pattern and progression of fine particulate matter fraction (PM_2.5) from the Clarity devices located in Angola, Cabo Verde, Nigeria, and Senegal during the period 2020 - 2022 are evaluated. The sensors are placed at different multi-sites, including urban and semi-urban zones and are influenced by emission sources that range from dust aerosols in Cabo Verde, Senegal and Northern Nigeria, to biomass burning in Southern parts of Nigeria and Angola. Other anthropogenic emissions sources are also present at different levels within each country, such as gas flaring, mining activities and urban traffic. We provide seasonal distribution of PM_2.5 along with diurnal patterns of PM_2.5 concentrations. The implications for human health are also considered in the context of the World Health Organization and US Environmental Protection Agency daily and annual guidelines.