File photo of Smog in Delhi on 1 November 2019. AP
New Delhi: Delhi’s PM2.5 pollution average for the July-August-September quarter this year stood at 37 micrograms per cubic metre, only marginally higher than the five-year low of 36 micrograms per cubic metre recorded during 2020, according to an analysis by the Centre for Science and Environment.
Pollution levels in the July-August-September quarter were preceded by one of the most polluted summers this year, unlike in 2020 when the trimester followed the cleanest ever summer (March-May) due to extraordinary conditions created because of hard pandemic lockdowns, the green think tank said.
“Therefore, it is important to understand what aided in cleaning up the Delhi air. Looking at the rainfall data it becomes evident that distribution of rainfall has a relatively higher impact on seasonal air quality than the absolute quantity of rainfall,” it said.
There have been 45 rainy days in July, August, and September this year as compared to just 39 rainy days in the quarter last year.
“These six extra rainy days helped keep the seasonal average low despite total rainfall this monsoon having been just one-third of the previous monsoon,” the CSE said.
These additional rainy days also pushed the regular start of bad air quality days further down the month of October, it said.
The PM2.5 average for the quarter stood at 38 micrograms per cubic metre in 2021, 41 micrograms per cubic metre in 2019 and 43 micrograms per cubic metre in 2018.
The CSE had on Thursday said the average PM2.5 pollution in Delhi in the winter season has declined by about 20 per cent as compared to the pre-pandemic period.
The PM2.5 concentration for winter (1 October to 1 February) used to hover around 180-190 micrograms per cubic metre before the pandemic. It has come down to 150-160 micrograms per cubic metre since then, it said.
However, the seasonal average is still over 150 per cent above the 24-hour standard (60 micrograms per cubic metre) and almost four times the annual standard (40 micrograms per cubic metre) despite the improvement, the green think tank noted.
What is PM2.5?
PM2.5 means Particulate Matter 2.5. There are particles in the air that are two and one-half microns or less in width. Microns are a unit of distance like inches and meters, but so tiny that an inch can fit around 25,000 microns. Particles in this size range can reach deep inside our respiratory tract, to the lungs.
How does PM2.5 affect health?
Exposure to such fine particles can cause short-term health effects such as eye, nose, throat and lung irritation, coughing, sneezing, runny nose and shortness of breath. This can also affect lung function and worsen medical conditions such as asthma and heart disease.
With inputs from PTI
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