Pollution levels were higher in Delhi this Diwali as compared to last year due to bursting of firecrackers and stubble burning, according to the Central Pollution Control Board’s (CPCB) report filed before the National Green Tribunal (NGT). In the report, the CPCB said Pitampura recorded an increase in PM (particulate matter) and SO2 indicating the impact of firecracker bursting on Diwali.
In 2020, on Diwali day, a decrease in PM 10 and PM 2.5 was observed as compared to pre-Diwali day by about 16 per cent and 18 per cent. This reduction is perhaps due to about 6 per cent reduction in the contribution of stubble burning this year, it added.
The board also apprised that as observed from real-time monitoring network (37 CAAQM stations), the hourly average concentration of PM 2.5 started increasing since 11 pm on November 14, it reached a peak in most of the stations at around 1 am and continued at higher levels till 5 am.
“The city-level average calculated for PM 10 and PM 2.5 concentrations on Diwali, were 645 ug/m3 and 483 ug/m3 respectively.” According to the report, in 2019 the PM 10 was increased by 70 per cent and PM 2.5 was surged by 149 per cent on Diwali day in comparison to pre-Diwali day.
It also cited comparative meteorology on pre-Diwali day and Diwali day observed during the last five years, which reveals that average mixing height on pre-Diwali day as well as Diwali day was lowest this year (2020), and said that this was due to the falling of Diwali in mid-November when the winter starts impacting decline in temperature and inversion starts.
“Mean wind speed at Parivesh Bhawan was 1.3 m/sec (3.4 Km/hour) on Diwali day which is lowest in the last five years creating unfavorable dispersion condition,” the report said. The CPCB carried out ambient air quality and noise level monitoring on the selected pre-Diwali day (November 9) and on Diwali in Delhi like previous years.
Ambient air quality was monitored at 40 locations — 3 manual stations and 37 real-time stations. The ambient noise level was monitored at 16 locations — 6 manual and 10 real-time noise monitoring stations.