The odd-even vehicle rationing scheme was started by the Delhi government on April 15 to clean up the air in Delhi which is considered the most polluted city in the world. The Delhi government was forced to take the road rationing measure for the first time in January as pollution levels touched alarming levels.

While most citizens agreed that the scheme helped bring down vehicular congestion in the first phase, its success in reducing pollution levels is still being debated. Incidentally, the city’s pollution control authority’s findings are at variance with those of other air monitoring agencies.

Reportedly, according to the Delhi Pollution Control Committee (DPCC), PM 2.5 levels were within the permissible limit of 60 micrograms per cubic metre of air (µg/m3) at 42 of 74 locations in the city on April 16. This, it said, was an improvement over the days preceding the scheme.

According to DPCC’s website, the PM 2.5 average between 8 am and 8 pm on Monday for three locations-Mandir Marg, Punjabi Bagh and RK Puram-was as low as 55 to 60 micrograms per cubic metre (g/m³) compared to 90-100g/m³ on April 15.

These findings, however, were at odds with The Energy and Resources Institute TERI’s claims that many places across the city witnessed an over-threefold increase in PM 2.5 levels on April 16 as compared to days before the scheme was implemented. It shows that while PM 2.5 levels at Anand Vihar stood above 160µg/m3 on that day (as compared to 55 on April 12) it was above 150µg/m3 at Punjabi Bagh (an almost four-fold jump from 41 on the earlier date).

Also for TERI, in Delhi and NCR, PM2.5 and PM10 concentrations violated the prescribed standards at many places, while NO2 levels are within the limits. 

The Ministry of Earth Sciences’ System of Air Quality and Weather Forecasting and Research (SAFAR), on the other hand on its website shows support to DPCC’s claims – stating that air pollution levels had undergone a steady decrease between Friday and Sunday. It remained constant on Monday and witnessed an increase on Tuesday.

Ozone levels in the atmosphere according to SAFAR were the lowest on Sunday as compared to the beginning of the month. It increased sharply on Monday but continued to remain in the safe zone. It however crossed the safe limit on Tuesday.

The picture may well become clearer by the time the scheme ends on April 30.