Spatiotemporal Assessment of Urban Particulate Matter Air Quality Index and its Implication on Human Health in the Kano Metropolis, Nigeria

Abstract

Rapid urbanization in Kano Metropolis, Nigeria, has led to significant air quality challenges, particularly concerning particulate matter  (PM) concentrations. This paper examined the spatiotemporal variations of the air quality of PM2.5 and PM10 in the Kano metropolis and  their implications for public health. Data on the pollutants were collected from 34 sampled locations across four distinct seasons hot and  dry (Bazara), warm and wet (Rainy), warm and dry (Kaka), and cold and dry (Harmattan) using HoldPeak Laser PM2.5-5800D Digital Meter  from March 2017 to February 2018. The data collected were subjected to Air Quality Index (AQI) computation, the outputs of which were used to spatially predict the concentrations of the unsampled areas through interpolation with the Inverse Distance Weighted (IDW)  model. Also, Analysis of Variance (ANOVA) was used to assess the spatial and temporal significance of the variation of the AQIs  over the metropolis. The results indicated no significant differences in the variation of PM2.5 AQI across seasons or locations [F(3, 135) =  0.453, p=0.0716] but with a significant difference in PM10 AQI [F(3, 132) = 5.360, p=0.002], with high pollutant concentrations exceeding  permissible guidelines in nearly all cases. This persistent pollution was attributed to the transboundary diffusion of emissions, leading to  a consistently poor AQI throughout the metropolis. The findings highlighted that all residents of the Kano metropolis are exposed to  dangerous levels of air pollutants, posing serious health risks. The paper concludes that air quality was poor across the study area all year  round. It recommends both local and regional monitoring of emission sources, to mitigate the adverse health impacts of pollution  and improve air quality for the urban populace.