While experts believe that restricting the number of vehicles on roads certainly helps in curbing air pollution due to emissions, there is no “drastic” change in the levels of pollution and there is still a long way to go to bring the air quality within the safe levels.

According to an analysis done by Delhi based NGO Social Action for Forest and Environment (SAFE), with respect to reduction in emissions, there was an approximate four-five per cent reduction in the pollution levels overall.

“This reduction is so minor that it is possible that it may not be visible on the air quality index. Maybe the results will be seen after some days. It was a good step, but, didn’t live up to the kind of hype created before,” said Vikrant Tongad, an environmentalist working with SAFE.

Most have hailed Chief Minister Arvind Kejriwal for showing “political will” in reducing pollution with the odd-even scheme, but, have maintained that it is difficult to link any improvement in air quality to the 15-day restriction.

Incidentally, the average levels of PM2.5 and PM10 recorded on Saturday (a day after the odd-even scheme ended) showed that both fell down sharply compared to previous days. While the former was in ‘Moderate’ range, PM2.5 was recorded at ‘poor’ category. It mostly falls under ‘very poor’ or ‘severe’ category.

Sumit Sharma, Fellow at TERI said, “Nobody should expect a very huge impact on the pollution levels due to the odd-even scheme. The share of private cars towards prevailing PM concentrations is less than five per cent, and hence, the effect of odd-even scheme on further reducing this could be even smaller. It is extremely difficult to delineate this small effect within the larger changes in pollutant concentrations due to meteorological factors”.

“Based on the contribution of private cars reported in previous studies, a marginal impact on air pollutant concentrations could be ascertained, which means that pollutant concentrations could have been marginally higher if the odd-even scheme had not been in place,” he added.

TERI analysed the ambient air pollutant concentrations in the city from December (before odd-even scheme) to January 15 at four stations – Mandir Marg, Punjabi Bagh, AnandVihar and RK Puram, managed by the Delhi Pollution Control Committee. It compared the 24-hourly averaged values against the prescribed 24-hourly average ambient air quality standard.

It was found that a decline was observed in the pollutant concentrations during the second week, but mainly due to meteorological influences.

“The percentage effect of odd-even scheme could be small, but when the concentrations are as high as in Delhi, the absolute reductions in PM2.5 concentrations are significant which can help reducing the health impacts,” a statement by TERI said.

However, the data captured by mobile vans during the implementation of the policy shows reduction in the concentration of peak levels of pollutants.

But experts argue that the peak values are not the best way to know if the pollution levels have come down or not.

Besides, the monitoring done by the mobile vans was only for twenty minutes at a particular location.

Analysis by Central Pollution Control Board (CPCB) and System of Air Quality and Weather Forecasting and Research (SAFAR) is awaited and are likely to be released on Monday.

Sharma and Tongad argue that both the Centre and the state government should look for other long term strategies to reduce pollution and use the current formula only in emergency cases.

“The vacuum cleaning of roads which Kejriwal has promised from April 1 should have been started by now. And the advisory issued by the Centre to the neighboring states to adopt measures to bring down pollution levels remains only on paper,” says Tongad.

Experts agreed that besides reducing congestion and bringing down traffic volumes, one major thing that the scheme has done is spreading awareness among the masses about the rising pollution levels in the capital and the need to tackle it.