Nigerian Journal of Environment and Health 2 (2019) 1–11 Prognosis of Emission Limits and Regulations for Vehicular Emission Pollutants in Nigeria A. F. Oluwole a , O. H. Joshua b,* , O. Oyediran a , S. Guttikunda c , O. I. Asubiojo b , I. I. Omoniyi d a SEEMS Nig. Ltd, 23B, Ixora Drive, M.K.O Abiola Gardens, Lagos. b Department of Chemistry, Obafemi Awolowo University, Ile-Ife, Nigeria. c Desert Research Institute, Reno, USA. d LAMATA, Block C 2nd Floor Motorways Centre, Motorways Avenue, Alausa, Ikeja, Lagos. Abstract The main purpose of this study is to propose a limit and regulation for vehicular emission in Nigeria using a prediction tool. Two (2) gas Analysers (the UEI – Automotive 5 gas fuel efficiency analyzer and Infrared Industries Inc – DC 5 gas analyzer) were used to measure concentrations of CO, CO 2 , HC, NO X ,O 2 and A/F Ratio from vehicular exhaust both in the idle and motion mode. The analyzer determines the Emission Factors (EFs) in gram per kilometer of pollutants based on distance covered and fuel consumption. EFs for both new and used vehicles are, at best, as good as EURO II. But EF for CO is 3 to 4 times that of EURO II. The determined EFs were used to calculate the Emission Inventory along a chosen corridor in Lagos Metropolis. A Simple Interactive Model is applied to estimate percentage reduction on emission from various six scenarios. Optimal reduction values are obtained when emission standards are changed from EURO II to EURO V, currently in vogue in India, Egypt and Brazil. Fuel switch from gas oil to CNG gives promising results. Emission standards based on EURO IV are proposed and methods of regulation and enforcement are discussed. c  NJEH 2019 Published by Living Science Foundation. 1. Introduction Vehicular emission is one of the major contributors to urban air pollution (Ostro and Chestnut, 1998). This is particularly so in developing countries like Nigeria where there is a preponderance of old, rickety vehicles with atten- dant air pollution-related health problems. The problem is compounded by increasing vehicle fleets, infrastructural limitations, poor engine/emission control technologies and limited provision for vehicle maintenance practices and emission standards. A country-wide inventory of air pollutants in Nigeria has been published (Obioh et al., 1988). The same workers also carried out an inventory and emission measurements of various transport modes in Nigeria (Obioh et al., 1994). Their results showed that the transport sector contributed over 10% of the greenhouse gases nationally and is responsible for about 30% of total fossil fuel consumption annually. More recent studies have esti- mated the contribution of transport sector to air pollution along a major corridor in Lagos State to be around 30-45% (LAMATA, 2007, 2009). Received April 2019; Accepted 17 August 2019. * Corresponding author Email address: trjoshua247@gmail.com (O. H. Joshua) 1