Delhi may fast be losing the gains it made in its air quality from the odd-even restrictions, the Centre for Science and Environment (CSE) said Thursday. The first three weekdays after the conclusion of the 15-day scheme have seen spikes in levels of Particulate Matter (PM) 2.5, said the agency.
The agency’s findings — for the first week after the odd-even scheme — suggest that without the moderating influence of the measures accompanying the plan, pollution levels are building up more rapidly.
According to the CSE’s analysis, data from the Delhi Pollution Control Committee (DPCC) indicates that PM 2.5 levels rose by over 57 per cent on January 18, with an average concentration across the city of 277 micrograms per cubic metre, which falls in the ‘severe’ category.
According to the agency, pollution levels continued to be in the ‘severe’ category on January 19, as levels of PM 2.5 pollution increased further, to 281 micrograms per cubic metre.
The city got a slight reprieve on January 20, as PM 2.5 pollution levels fell to 266 micrograms per cubic metre. According to the CSE, this was possible due to higher wind speeds, which possibly dispersed the pollutants.
“This validates the importance of emergency action. The fortnight when the programme was implemented has clearly demonstrated that peak pollution levels are lower than the normal smog peaks of the season, despite adverse weather conditions,” said Anumita Roy chowdhury, executive director of CSE.
While comparing these trends to those witnessed during the odd-even scheme, Roychowdhury said the lowest pollution curve between January 1 and 15 could be seen largely during the afternoons, between 2 pm and 5 pm. “But this lowering of curve is getting gradually flattened in the days following the scheme. This means that pollution is building up throughout the day,” she explained.
Despite lower wind speed on January 1 in comparison to January 18, PM 2.5 pollution levels were higher on January 1, pointed out CSE.
While peak pollution during the odd-even scheme was much lower, “now, the smog episodes have much higher peaks and a more rapid build-up,” said Roychowdhury.
Other studies carried out by the School of Planning and Architecture (SPA) showed that traffic congestion had also reduced considerably while the scheme was in force. This had an impact on roadside pollution, said CSE scientists.
The ‘Traffic Survey and Travel Attributes Study’ — conducted by SPA’s department of transport planning — also found “substantial reduction in traffic volume and congestion”.
The survey was carried out in 11 locations along major arterial roads like the Gurgaon Expressway, Mathura Road, NH-24, NH-1, Bahadurgarh Road and Ring Road.
It found that the average speed of a journey was as high as 50 kmph during the odd-even plan, as against 20-25 kmph on regular days.
The busy Ring Road experienced about 30 to 50 per cent increase in the average speed of vehicles during the odd-even fortnight.
The study also found that the average occupancy in personal cars at major nodes increased from 1.4 to 2.1 during the odd-even scheme.