Pollution in Delhi breached emergency levels on the Diwali night and the air quality has since progressively deteriorated, but compared to last year, the city was relatively better off, the pollution monitoring agencies today concurred. The Central Pollution Control Board (CPCB) released data showing a significant fall in volume of particulates PM2.5, PM10 and gaseous pollutant SO2 (sulphur dioxide) recorded by its stations across the national capital on the Diwali night, as compared to last year.
However, the volume of pollutants were almost identical, at places even higher, when placed against the figures of 2014 or 2015, making it difficult to attribute the marginal dip to any particular factor, such as the ban on the sale of firecrackers in the region by the Supreme Court on October 10.
The CPCB’s Diwali day air quality index had a score of 426 last year, which falls in the ‘severe’ – or the most polluted – category. This year, it was 326, in the ‘very poor’ category, a shade better.
However, the overall air quality index (AQI) of the city, as recorded by CPCB, was 403 today, which is in the severe category. CPCB’s monitoring network has also expanded over the the last one year with the addition of around 10 new stations.
Dipankar Saha, head of CPCB’s air lab, said inspite of non-favourable meteorological conditions such as lesser distribution of pollutants and low wind speed leading to their stagnation, the air quality on Diwali has shown an improvement over 2016.
The Centre for Science and Environment (CSE) said the pollution levels worsened this morning due to calm wind and higher moisture in the air – as was predicted. “Since October 1, PM2.5 levels have largely hovered around ‘poor’ to ‘very poor’ categories. But this breached the emergency level on Diwali night,” Anumita Roychowdhury, executive director-research and advocacy, CSE, said.
CSE’s analysis also established the fact that this year’s Diwali morning and evening were promising indeed, with little or no firecrackers being burst across localities. But as the revelry picked up, the air quality declined.
“During the day (about 13 hour average – 6 am to 7 pm) the levels in Delhi and NCR towns of Gurugram and Ghaziabad were in ‘very poor’ category (Delhi – 139 micrograms per cubic metre (ug/m3); Gurugram – 121 (ug/m3); and Ghaziabad – 142 (ug/m3).
“However, during Diwali night (about 12 hour average – 7 pm last night to 7 am this morning) the levels in Delhi, Gurugram and Ghaziabad were in emergency level. (Delhi- 548 (ug/m3); Gurugram – 382 (ug/m3); Gaziabad – 501 (ug/m3)),” CSE said in a statement. The 24-hour safe limit of PM2.5 and PM10 are 60 and 100 respectively.
The Delhi Pollution Control Committee (DPCC) also released data based on monitoring at 16 sites. According to its data, levels of PM2.5 and PM10 showed a marginal dip compared to last year.