The effect of odd-even driving scheme on PM2.5 and PM1.0 emission.

Graphical abstract Highlights • We monitored PM levels pre and post odd-even driving scheme in Delhi city, India. • We find that the scheme has reduced the PM 2.5 and PM 1 levels at traffic corridors. • The reduction of PM 1 is found higher than that of PM 2.5 during the days of scheme. • We find gross non-conformance towards NAAQS values for PM at traffic corridors. • Timely implementation of more stringent emission norms need to be ensured in Delhi. Abstract According to a global survey of 1600 cities by WHO in 2015, Delhi was found to be the most polluted city in the world, highlighting immediate need to bring in appropriate and effective measures to ensure a healthy air quality throughout the city. In a bid to do so, the odd-even driving scheme was implemented a few years ago in Delhi city on a trial basis requiring the vehicles bearing odd and even registration numbers to run on alternative days with effect from 1st January 2016. Applied for the very first time in India and lasting on a pilot basis for 15 days and also referred to as Phase 1 of implementation, the scheme ended on 15th January 2016 with primary goal of assessing the extent to which such a scheme could serve as an effective measure to bring down and control the excessively high ambient air pollution levels. Other associated benefits, which the study considered, were decongestion of city roads, and promoting use of public transport system and carpooling, besides other alternative modes of transport. The paper presents a comparative analysis of particulate matter concentrations recorded before and during the implementation of odd-even scheme of Phase 1 for three key traffic corridors of the city. The study reports an average reduction of PM 2.5 of 5.73% and that of PM 1.0 of 4.70% in the ambient air across all the corridors during the days of implementation of scheme, which depicts a small but positive impact of the measure adopted towards abatement of urban air pollution in the megacity of Delhi. Capsule: The study finds that the odd-even driving scheme can help to reduce particulate matter levels compared to non-scheme days at traffic corridors. [ABSTRACT FROM AUTHOR]