Odd-even formula has no clear trend, says Pollution Board

An analysis by the Central Pollution Control Board on the impact of odd-even formula in Delhi says that no clear trend has been observed in the concentration of pollutants during the scheme.

The Central Pollution Control Board (CPCB) monitored seven pollutants — PM 2.5, PM 10, SO2, Benzene, O3, NO2, and CO — through eight Continuous Ambient Air Quality Monitoring Stations (CAQMS) and seven manual stations, which operate on alternate days.

The data was collected for days during the scheme, preceding (from December 25 to 31, 2015) and post (from January 16 to 21, 2016) its implementation.

During January 1-15, PM10 ranged between 161-629 µg/m3 and PM 2.5 79-507 µg/m3. The data analyses for days preceding to the odd-even scheme shows PM10 between 142-454 µg/m3 and PM2.5 between 52-298 µg/m3. Similarly, during the post odd-even scheme, PM2.5 ranged between 76-342 µg/m3.

“With no clear trend and wide fluctuations observed in the concentrations, it is evident that the meteorology and emissions from other polluting sources have been major factors impacting air quality of Delhi during the period,” the report said.

“The odd-even scheme could have theoretically contributed to PM reductions in respect of exhaust emissions from off-road odd or even cars, marginal reduction in road dust and secondary particulates,” it added.

The analysis shows that meteorological factors have a huge role to play on the pollution levels in the city and that higher wind speeds and mixing height result in better dispersion and lower pollution levels.