Presentation for Osho.Y.B(June 2015)
- 1. MULTIVARIATE ANALYSIS OF THE ENVIRONMENTAL IMPACT OF TRAFFIC DENSITY ON AIR QUALITY IN LAGOS, NIGERIA – Osho Y. Babatunde. Gap in Knowledge: Existing research often overlook the importance of land use mix, traffic density, road intersection density and topography in accounting for spatial variability in the predicted air quality surface. In addition, spatial autocorrelation and high standard errors have limited the utility of some existing air quality models. Aim:The research aim to develop a robust methodology for air quality data collection and on the basis of this, identifying traffic-related predictors of air pollution in the Lagos metropolis, Nigeria. Methodology: Road network map, vehicle count data, number of road intersections and average slope per square kilometer were derived from existing road network data and the Shuttle Radar Topographic Map (SRTM). Data was converted to density map using a 1x1Km grid and subsequently converted to raster maps. To overcome the inconsistency in data values, the different maps were rescaled and standardized to between 0-1 data range and were combined using a Weighted Linear Combination (WLC). Pixels in the resultant map were classified into three categories and subsequently overlaid on the land use map to guide field data collection. Stratified random sampling strategy was adopted to ensure that data collection covered all the identified land use types and different traffic related hierarchies. Air quality parameters- carbon monoxide (CO), nitrogen dioxide (NO2), particulate matter (PM2.5) were collected at each identified locations using digital air quality monitoring equipment. Empirical Bayesian Kriging (EBK) was used for the interpolation because it accounts for spatial dependence and accurate standard error in prediction. The predicted surface serves as the basis for modelling the distributional pattern of air quality within Lagos metropolis and was subsequently used for the land use regression. Results: The study showed significant relationship between vehicular traffic and emissions (F= 783.018, P<0.05). Further work: A preliminary study was undertaken to demonstrate the feasibility of the methodology using the Apapa LGA within metropolis. Additional LGAs (Ikeja and Lagos Mainland) are being considered. Criteria for selection of additional LGAs include; health records, population density and vehicle registration per LGA. Seasonal variations is in air quality is also being considered.