Geo-Spatial Mapping of Air Pollution in Benin City, Nigeria

Abstract

The study investigates the distribution and mapping of air pollutants in Benin City using land use and administrative maps, a Global Positioning System (GPS) device, Geographic Information System (GIS) techniques and field sampling. Air sampling for the study covered a period of six months, between mid-October 2013 and mid-April 2014. Air pollutants of concern included particulate matter (PM0.3, 0.5, 1.0, 2.5, 5.0 and 10 µm) and carbon monoxide (CO). Particulate matter was measured using a hand-held particle counter, while CO was measured with a single gas monitor (T40 Rattler). Five sampling points, coordinates of which were determined using the GPS device, were selected based on stratified sampling technique and they represented the five land use types monitored in the study area (i.e. institutional, agricultural, commercial, industrial and residential). Sampling was carried out twice weekly in accordance with the guidelines of Central Pollution Control Board, Delhi India. Sampling height was two meters above ground level. Field data was inputted into a GIS data base from which interpolation and spatial correlation analyses were carried out. The results showed that commercial and industrial areas were characterized by higher concentration levels of pollutants, while institutional and agricultural areas were characterized by less of same. The study recommended appropriate actions by town planning authorities in addressing the challenges of air pollution resulting from improper zoning systems, adjacent placement of incompatible land uses, inadequate barricading of high air polluting land uses and non compliance to land use permitting process.