Real-world emissions of gaseous pollutants from motorcycles on Indian urban arterials

Abstract

Motor vehicles contribute significantly to the total emissions in a city. Several studies have attempted to quantify emissions from cars, buses, and trucks using laboratory-based or real-world emission tests. However, real-world emissions from motorcycles (or motorized two-wheelers) has not received adequate attention. Unlike developed countries where cars are predominantly used for personal transport, motorcycles are widely used in developing countries. In this study, we quantify emissions of carbon monoxide (CO), hydrocarbons (HC), and nitric oxide (NO) from four typical motorcycles (MC 1, MC 2, MC 3, and MC 4) using real-world emission measurements and develop emission models. We also compare the observed real-world speed-time profiles with the laboratory test cycles and the emission factors developed using real-world emission measurements with the Bharat Stage (BS) emission standards. The real-world emission factors of CO for MC 1, MC 2, MC 3, and MC 4 were 12.3 times, 3.18 times, 9.71 times, and 5.84 times above the respective BS emission standard values. Also, the CO and [HC + NO] emissions from a two-stroke motorcycle (MC 1) were higher than the four-stroke motorcycles. The models presented in this paper can be used to accurately quantify real-world emissions from motorcycles on Indian urban arterials and to formulate policies for air quality improvement.