The ban observed on the sale of crackers during the festival of Diwali definitely brought down the levels of pollution on Diwali as the air quality this year was much better than compared to last year. The city may have chocked after that due to multiple reasons but the firecracker-free Diwali observed in the national capital saw a 39 per cent decrease in PM 2.5 levels compared to 2016. According to data collected by the Central Pollution Control Board (CPCB) from three monitoring stations — Pitampura, Janakpuri and from CPCB’s headquarters’ at Parivesh Bhavan — reductions in 12 of the 13 elements usually found in firecrackers were noted.
As per the data shared by CPCB, a 64 per cent decrease in Strontium was seen in Delhi’s air. Strontium is the element which gives firecrackers a red colour. However, the concentration of Titanium saw a marginal increase. Air laboratory Chief, D Saha of CPCB on Friday said that the better air quality on Diwali was ensured due to the Supreme Court’s decision to ban the sale of firecrackers in the Delhi-NCR. He stated that it was the apex court’s “foresight” helped the blow in a year that also saw adverse weather conditions coincide with the festival, reported The Indian Express.
The CPCB shared another report which compared “air pollution episode days” in 2017 and 2016. The report found that 2017 was more critical than the previous year with respect to meteorological conditions. D Saha said, “This year was more critical than last year with respect to mixing height, wind speed and relative humidity.” He continued, “With higher humidity, the weight of the pollutants moving in the air increases and then fall closer to the ground level,” he said.
The wind speed was in the range of 1.0-3.0 m/s between October 30-November 7, 2016, compared to 1.0-1.3 m/s between November 7 and 12, 2017. Further, mixing height was 146-618 m last year, compared to 336-479 m this year. While mixing height is the height of vertical mixing of air and suspended particles above the ground, a lower mixing height suggests worse air.
The relative humidity also decreased. It was seen in the 47.8-63.3 per cent range in 2016 compared to 60.2-75.8 per cent this year. This which weighs down pollutants to bring them closer to the ground. Meanwhile, among the elements found in firecrackers, the data shows a 51 per cent decrease in Barium. Barium is responsible for providing green colour in firecrackers.
Reductions were also seen in other hazardous chemicals. Iron concentrations at 48 per cent, Calcium at 37.8 per cent and Zinc was seen at 41 per cent among other elements. CPCB scientist Abhijit Pathak said, “Reduction was seen in most elements, including Aluminium, Potassium, Sulphur… and elements such as Calcium and Barium that provide the colours in firecrackers.” He added, “Except, there was an increase in Titanium levels.”