Quantifying the Visibility and Human Health Effects of Aerosol Optical Depth Chemical Species in Some Cities of West Africa

The high level of chemical compounds in the atmosphere of many West African cities is worrying because of the potential threats to human health and other environmental problems they are known for. However, routine monitoring and adequate control measures are rare due to technical, social and economic problems. This paper analyzed the health and visibility effects of aerosol optical depth chemical species within some West African cities from (2010–2020) using the aerosol optical depth data set obtained from the European Center for Medium-Range Weather Forecasts (ECMWF-UK). The results of the analysis showed that the visual range of the study cities ranged from 4600 to 5600 km, while the potentials of human health effects T_PHhe existing in the cities are between 0.9 and 1.2 signifying low visibility and high potential threats to human health. There exist several weak and also inverse correlations between the variability of the aerosol optical depth chemical species in the study cities with a coefficient of determination \({r}^{2}\) $r^2$ ranging from 0.01 to 0.98. This implies that aerosol loads are not uniformly distributed across cities and also come from a plethora of sources across cities. The variability of aerosol optical depth chemical species in the West African cities presented is useful in evaluating and improving the accuracy of the models for aerosol prediction in the region and can assist in the easy determination of aerosol effects in the atmosphere. The total chemical composition of aerosol loads was gauged with acceptable standards limit set by Environmental Protection Agencies to determine the health effects on humans and the results are useful not only in measuring the health implication but also in evaluating safety measures to tackle the effects, while the identified poor visibility in the cities is a clear call for policymakers to step up regulation and design action to tackle the menace of visibility reduction in these cities.