There seems to be no early end to this debate on if the odd-even strategy implemented from the Delhi Government in January 2016 was a victory or not.

Representational image. PTIRepresentational image. PTI

A new research study, published in the journal Current Science, indicates that the rule did not lead to a reduction of vehicular emissions, and surprisingly, even resulted in an overall growth in emissions. It has found that there has been a substantial increase in the median concentration of gases which were measured from air samples as chemical tracers for vehicular emissions.

The median concentration of 13 from the 16 gases measured were higher in morning (7 am to 8 am) and afternoon hours (1.30 pm to 2.30 pm) on days when the plot was implemented as contrary to three random benchmark days before and after the fortnight-long odd-even campaign.

Speaking to India Science Wire, Dr Vinayak Sinha, a member of the study team from IISER, clarified the higher concentration of gases was likely due to the simple fact that though there was a reduction in the number of automobiles, there was an increase in the number of different vehicles on the street: public transportation buses, trucks, two wheelers, three wheelers along with CNG-operated automobiles which were exempted from the strategy.

A study by the Council on Energy, Environment and Water (CEEW) had discovered that the daily average number of vehicles rose by 10 percent during the odd-even interval in January 2016 compared to the last week of December 2015. The growth was attributed primarily to a 17 percent increase in two-wheelers, 12 percent increase in three-wheelers, 22 percent rise in taxis and 138 percent rise in the number of private buses.

In addition, a high number of personal vehicle owners seemed to have chosen to sail earlier in the afternoon and later in the evening, before and after the odd-even rule was enforced (from 8 am to 8 pm) to prevent penalty.

The study says “the odd-even rule could have led to traffic decongestion during peak hours, which might certainly have profited commuters. But it also has to be considered that improved traffic emissions through times of the day when the dilution effect due to the atmospheric boundary layer is low (early morning until 8 am and during the night after sunset) could lead to higher peak concentration vulnerability for many health-relevant carcinogenic VOCs (volatile organic compounds) such as benzene”.

The report indicated that in future, arrangements be made for deploying methods for internet measurement of VOCs at multiple strategic websites and webcams at sampling sites to get a better picture of the number and type of vehicles passing by. This would help address current uncertainties with regard to quantitative source apportionment of air pollutants.

Apart from Dr Sinha, the study team included Dr B.P.Chandra, H.Hakkim, A.Kumar, H.Pawar, A.K.Mishra, G. Sharma, Pallavi, and S.Garg of IISER, Mohali, SachinD.Ghude, D.M.Chate, Prakash Pithani, and Rachana Kulkarni of IITM, Pune and R.K.Jenamani of IMD, Delhi.


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