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Six gaseous pollutants may be included in Delhi-NCR’s AQI from next year

As of now, Delhi’s AQI is primarily based on two parameters – PM2.5 and PM10 – that dominate air pollution in the region. On certain days their levels shoot up nine to 10 times above the permissible limits in winter.

delhi Updated: Oct 21, 2017 23:26 IST
Joydeep Thakur
Joydeep Thakur
Hindustan Times
delhi,delhi news,delhi pollution
As of now, Delhi’s AQI is primarily based on two parameters – PM2.5 and PM10 – that dominate air pollution in the region. On certain days their levels shoot up nine to 10 times above the permissible limits in winter. (Sonu Mehta/HT PHOTO)

The Environment Pollution Control Authority (EPCA) is exploring options to take into account the levels of six gaseous pollutants in the Air Quality Index (AQI) of Delhi from the next winter.

It would give the Supreme Court-mandated panel a more holistic view of the Capital’s pollution scenario, based on which the Graded Response Action Plan could be enforced.

As of now, Delhi’s AQI is primarily based on two parameters – PM2.5 and PM10 – that dominate air pollution in the region. On certain days their levels shoot up nine to 10 times above the permissible limits in winter.

“This is the first time we are implementing the GRAP based on the AQI, which takes into account the levels of two primary pollutants – PM10 and PM2.5. We don’t want to disturb this setup as of now. But we are exploring options to include the levels of six other gaseous pollutants in the Delhi-NCR’s AQI from 2018 winter,” said Sunita Narain, a member of EPCA and director of the Centre for Science and Environment.

Even though PM10 and PM2.5 have been found to be the primary pollutants in the city’s air, the levels of some gaseous pollutants such as SO2, NO2 and Ozone among others spike occasionally after festive seasons because of cracker bursting and unfavourable meteorological conditions.

A task force of the Central Pollution Control Board headed by the member secretary of the country’s apex pollution monitoring is, however, constantly keeping a track on the levels of all the six gases round the year.

“The National Air Quality Index takes into account eight pollutants, including PM10, PM2.5 and six other gases. But as the levels of particulate matter exceeds several times the permissible limit in Delhi-NCR we take into account these two as far as region’s AQI is concerned,” said A Sudhakar member secretary of CPCB.

Firecrackers are loaded with a range of metals such as aluminium, strontium, copper and barium apart from the usual ingredients such as black powder, dextrin, paper and glue, which upon bursting emits a range of gases and pollutants such as SO2, NO2 and other compounds.

Experts, however, said that till Saturday, there had been no incidents of sudden spurt in the levels of any of the gases barring one incident, in which the level of carbon monoxide had shot up in one of the monitoring stations. It was, however, momentary and primarily because of the calm winds.

“The levels of PM10 and PM2.5 shoot up several times above the permissible limits. But the levels of NO2 and SO2 seldom cross the permissible limit. Even if they cross they remain within the safe range and never hit the ‘very poor’ or ‘severe’ levels,” said D Saha head of the air quality laboratory of CPCB.

For instance the level of NO2 touched 146 micrograms per metre cube at Anand Vihar around 3 pm on Saturday. It was in the ‘moderately polluted’ zone. It is considered ‘good’ if NO2 stays below 40 micrograms per metre cube.

First Published: Oct 21, 2017 23:25 IST