The national Capital’s air quality changed to “good” from “moderate” on Tuesday as the advisory status about Delhi air quality in the National Air quality Index (NAQI) was modified after the minimum value of Particulate Matter (PM) 2.5 was observed at 9 µg/m3(micrograms per cubic) and maximum value of the same pollutant was recorded 54 µg/m3.
Both the values are under the prescribed limit of the Indian Metrological Sensors.
The pollution levels were remarkably low not only in inner Delhi but in the outskirts of the city. During the first phase of odd-even, Anand Vihar area was considered as red zone because of high pollutant levels while this time round, mass concentrations of both the pollutants around Anand Vihar has been found to be very low.
Taking into account the real time air data of the Delhi Pollution Control Committee (DPCC), value of PM 2.5 was 24 µg/m3 in Anand Vihar area owing to normal wind speed.
However, RK Puram was an exception where the pollutants level was marginally high.
The pollution forecast of SAFAR, a unit of Ministry of Earth Science (MoES) also predicted that mass concentration of PM 2.5 is likely to fluctuate between 51 and 54 µg/m3 for the next three days.
Environmentalists with the National Physical laboratory (NPl) said Delhi climatography and geography is different. “Apart from weather, wind activities like dust storm or burning of agricultural waste are the main factors while in April and March month, none of these activities take place,” said the scientist.
Values of other pollutants that have adverse impact on humans have been recorded as “low” on the Ambient Air Quality Monitoring Systems. Value of carcinogenic compound Benzene was 1.5 µg/m3 while other pollutants like CO, Nitrogen Oxide, Ozone and Sulphur Dioxide were also on the lower side.
Meters of the United States Embassy at Chanakyapuri also reflected moderate values of PM 2.5 and PM 10. In New Delhi, value of PM 2.5 was 57 µg/m3 at 5 PM which is relatively low whereas in December -January 2015-16, value of same pollutant fluctuated between 400 and 800 µgm-3. Moreover in October and November, the concentration hit the highest point which was 1000 µgm-3.
IMD official said wind speed also plays pivotal role in bringing down pollutant values low. According to IMD sensors, wind speed recorded during day time was 1.4 meter per second with 233 degree.
It was observed that during the pilot run of odd-even scheme, no significant changes had occurred in pollutant values. Moreover, the observations of Central Road Research Institute (CRRI) during the pilot run of the scheme also showed that the overall impact of the scheme was more on traffic congestion not on air pollution, said an environmentalist.
“Implementation of odd-even vehicle by the Delhi’s Government led to significant reduction of 15-20 per cent in traffic volume across the most congested stretch (Matura Road) in the NCR,” the CRRI report then said.