PROJECTION OF CRITERIA AIR POLLUTANTS EMISSION FROM ON-ROAD VEHICLES IN THE MEGACITY OF LAGOS, NIGERIA
The increase in the mode of transportation has become a serious environmental threat that has resulted in the emission of criteria air pollutants (CAPs) into the atmosphere. These CAPs are sulphur oxides (SOx), particulate matter (PM), lead (Pb), carbon monoxide (CO), and nitrogen oxides (NOx). This study examined the emission of CAPs from road traffic use in Lagos State. Data for the inventories of the production of these five sources were taken from 1997–2011 and were used to forecast CAPs emissions from 2012–2030. The petroleum products consumption data were sourced from the Nigerian National Petroleum Corporation (NNPC). Five categories of CAPs were studied and their corresponding emissions from 1997–2011 were computed as follows: SOx: 209–15,358t, NOx: 2,038–25,692t, CO: 24,996–186,202t, PM: 155–995t, Pb: 0.8 4.5t. Projection and forecasting of CAPs emissions from 2012 to 2030 were carried out using the Box Jenkins ARIMA method. There were close similarities between the observed and forecast values. The predicted CAPs emissions between 2012 to 2030 will be 309t for SOx, 22,600 – 41,300t for NOx, 100,000 – 300,000t for CO, 414t for PM, and 0.7t for Pb. The study concluded that there is tendency for these CAPs emissions to increase if the authorities and stakeholders do nothing. Several mitigation measures aimed towards reducing future CAPs emissions in Lagos State were recommended for the various sources.