'No significant change in air quality during odd-even 2'

The impact of odd-even 2.0 on air quality was less in comparison to the first phase in January, green body TERI said, observing that the scheme should be brought out only during “high episodes” of pollutants concentration and cautioned Delhi government against its regularisation.

 According to an impact assessment study done by The Energy Resources Institute of India (TERI) on the road rationing scheme, there was a “small” four per cent reduction in pollution levels in the capital. This was lower than seven per cent reduction, which was estimated during phase one of the odd-even scheme.

To ascertain the effect of the odd-even scheme on PM 2.5 concentrations, a box model was applied.

The model was used to delineate the effect of the scheme from daily changes in air quality due to meteorological factors like wind speeds and mixing height.

 It was found that the four per cent reduction in PM 2.5 was due to 17 per cent decrease in car numbers.

Insignificant reduction

 “The reduction achieved from scheme seems is not insignificant but too small to be captured among other more dominating factors. The air quality benefit is limited,” said Sumit Sharma, Fellow, TERI, while presenting the findings.

 Along with the decline in impact of odd-even in curtailing pollution from the last phase, the study also found out a decline in the improvement of average speed of cars this time.

 An increase of 13 per cent was observed in the average speed in the second round, compared to 17 per cent registered in January.  TERI carried out traffic counts at six locations – Ghazipur border, DND Noida, Gurgaon border, Shankar Road, Ring Road (Hyatt Hotel), and BSZ Marg between 7 am and 11 pm during, before and after the scheme.

 “This could be probably due to people opting for second cars with alternative number plates, CNG kit installations or enhanced use of taxis,” said Sharma.

 Experts pointed out that regularising the scheme is “not a good idea” as it not going to give large benefits over the years. The scheme, they suggested should be brought out in winter months when pollutants are trapped in the air to see a “perceptible” difference.

 “We feel there was a lower compliance during the second odd-even. The analysis of both the phases of the scheme suggests that regularising it can reduce its impact. It is only useful when high pollution episodes are expected like when inversion layer is down, wind speed and mixing height is low. The longer this scheme is continued, the more ways people will find to adapt to the system,” said Ajay Mathur, Director General, TERI.

Comparative study

 The Delhi government is currently doing a comparative study of the two models of odd-even (January and April) and has said any decision on its third round will be taken after its completion.

 Further, TERI recommended alternative solutions such as ‘congestion pricing’ which is based on a ‘pay-as-you-use’ principle with an aim to reduce the number of vehicles and in turn encourage modal shift by charging vehicles on entry in restricted/congested zones/times.