Visibility as a proxy for air quality in Nigeria from 1950 to 2020

Nigeria is the largest country in Africa by population. Currently, the population is estimated to be 219 million making it the 7^th largest country worldwide. Demographic trends suggest that rapid population growth will lead to a population of approximately 400 million by 2050, which would make it the 3^rd largest country worldwide. 

Air quality in Nigeria is routinely reported to be poor due to both natural and anthropogenic sources of air pollution.  There are a limited number of air monitoring stations within Nigeria, and a corresponding lack of long-term air quality data, with which to assess its long-term trends. With the advent of low-cost monitoring, there has been a recent upsurge in measurements in Nigeria, but these measurement campaigns tend to short term and difficult to discern long term trends from. Nonetheless, these measurements show clearly that particulate matter (PM) air pollution regularly exceeds the WHO guidelines for both PM₁₀ and PM_2.5 size fractions, and hence PM places a high health burden upon the population.

This study uses visibility readings in Nigeria, measured since the 1950s, to study and understand historical and contemporary levels of air pollution. Visibility is related to the atmospheric extinction coefficient that is largely determined by the amount of PM in the atmosphere. New machine learning calibration techniques allow for PM_2.5 mass concentrations to be estimated directed from visibility and other meteorological measurements.  This presentation will discuss the visibility derived PM findings for the different regions of Nigeria. It will highlight trends in both regional scale and more localized sources of PM.  The implications of population growth and other socio-economic factors upon potential air quality scenarios for Nigeria will also be discussed.