Delhi entered its fifth day of the odd-even scheme on Tuesday and the results, though premature, seem partially optimistic. According to data collected by The Energy and Resources Institute (Teri), pollution levels dipped on Monday, the first full-fledged traffic day since the start of the second road rationing scheme.
Monitoring stations across the city, set up by the Delhi Pollution Control Committee (DPCC), recorded lower pollution levels on Monday (April 18) than on Saturday (April 16). However, the data showed levels had spiked considerably when compared with last Tuesday (April 12), before the odd-even rationing began restricting odd and even number licensed cars to ply on alternate days.
Teri is collecting daily data from four DPCC monitoring stations and is also monitoring another five locations for air quality. This data, made available to Hindustan Times, showed that the city’s air was marginally cleaner on Monday than on Saturday, the second day of the scheme.
At Anand Vihar, one of the most polluted corners of the Capital, concentration of PM 2.5 – particulate matter with a diameter of 2.5 microns – was recorded at 122 micro gram per cubic metres (µg/m3) on Monday. On Saturday, PM2.5 levels were at 168 µg/m3 while last week they were 55 µg/m3.
The Indian permissible standard for PM 2.5 is 60 µg/m3 while the World Health Organisation, that listed Delhi’s air quality as the worst in the world last year, considers 25 µg/m3 to be of good quality.
PM 2.5 is huge concern as the particulate matter, released by vehicular and industrial emissions, is tiny enough to penetrate deep into lungs and cause severe respiratory and cardiac problems. The matter is so fine that even most protective masks available in the market cannot filter them out.
Teri experts monitoring pollution levels attribute the differing levels to the changing wind speeds.
“On Saturday, air pollution increased as the wind speed, which results in dispersion of pollutants, was comparatively less at 6km/h. On Monday, it was 8 km/hour. However, it is too early to link this dip in pollution level with odd-even scheme,” said Teri’s Sumit Sharma who led the monitoring team.
Sharma added that a detailed analysis is required to ascertain the actual impact of the second phase of road rationing after it concludes on April 30.
The Delhi government took the extreme measure for the first time in January as pollution levels touched alarming levels in the city.
The DPCC, which monitored a total of 74 locations, earlier said PM 2.5 levels were within the permissible limit of 60 µg/m3 at 42 locations on Saturday, underscoring that the government’s scheme was having a positive impact on air quality.
Officials said nearly 69 locations registered PM 2.5 levels at below 100, while PM 100 levels were below 200. The meteorological department however cautioned that Tuesday could be a bad day as very weak wind speeds could increase PM2.5 and PM10 levels across the city.