Revisiting transport policy through idling exhaust measurements from two-wheelers - A case study

The automobile sector in India contributes significantly to the ambient air pollution, with two-wheelers (2-Ws) dominating the urban vehicular fleet. The existing phase-out policy for 2-Ws is only based on its age, regardless of other vehicle-specific parameters (VSPs). It is imperative to ascertain key VSPs affecting 2-Ws emissions from the perspective of strengthening such policy. Through real-time exhaust emission testing of 575 2-Ws, the present study finds that VSPs such as mileage, age, and complying emissions standards have a very strong influence on the tailpipe CO and HC (carbon monoxide and hydrocarbon). 2-Ws age and mileage were both significantly correlated with CO and HC (For age, R² = 0.85 and 0.82, respectively, and for mileage, R² = 0.84 and 0.81 respectively). Further, the fuel ignition system played a significant role in CO and HC emissions as it was discovered that more recent and sophisticated versions of 2-W engines had lower maximum emissions values when compared to older versions.. Also, kerb weight has a weak correlation to HC and CO emissions (R² < 0.3), implying that approximately 30 percent of vehicles with the same kerb weight had the similar CO and HC emissions. At present, the 2-W scrapping policy is solely based on its age of fifteen years regardless of any other variables. The study recommends that the relevant environmental and scrappage policy for 2-Ws be suitably upgraded to include mileage as a key factor. It is need of the hour in achieving the desired results towards safer and sustainable transportation.