Pollutionthissummerworstin 4years; expertsblamedryspell

The national Capital saw the worst summer pollution since at least 2019 this year, with each of the four months from March to June recording pollutant levels higher than the prescribed national safe limits, research by Climate Trends, an organisation that works on climate and environment, has found.

The study, carried out using Central Pollution Control Board ( CPCB) data collated on the NCAP Tracker, analysed Delhi and nine other cities that breached limits to see the summer trends.

It found that Delhi failed to meet the annual safe standards of PM2.5 and PM10 (fine particulate matter of diameters less than 2.5 and 10 microns) in any of the four months.

The average PM2.5 level was 86.59ug/m3, over two times the annual national limit of 40ug/ m3, while the average PM10 level was 249.9ug/m3, over four times the national safe limit of 60ug/m3, the study found.

Besides Delhi, the other cities that were analysed include Agra, Bengaluru, Chandigarh, Chennai, Kolkata, Jodhpur, Mumbai, Lucknow and Patna. Aside from PM2.5 and PM10 levels, the study also looked at NO2 (nitrogen dioxide) levels for the months of March, April, May and June.

While the India Meteorological Department (IMD) considers June as a monsoon month, it is mostly dry in several parts of the country and was included in the analysis, researchers said.

The average PM2.5 level in March was 98.98ug/m3, which rose to 105.19ug/m3 in April, decreasing to 81.48ug/m3 in May and further to 60.73ug/m3 in June.

The average PM10 level, largely comprising dust, was even higher at 231.4ug/m3 in March, 291.12 ug/m3 in April, 246.51 ug/m3 in May and 230.74 ug/m3 in June.

In comparison, last summer (2021), when Delhi saw a partial impact of lockdown towards the end of April and May, the average PM 2.5 over the four months was 72.79ug/m3, while the average PM10 was 194.47ug/m3.

The figures for the summer of 2020, when a nationwide lockdown was in place to combat the pandemic, are not available, while in 2019, a pre-Covid year, the average PM2.5 level during the summer was 79.5ug/ m3, while the average PM10 was 218.3ug/ m3 -- both figures lower than the readings for this year.

While CPCB’s limits for PM2.5, PM10 and NO2 are 40ug/ m3, 60ug/ m3 and 40ug/ m3 respectively, the World Health Organization’s (WHO) safe limits are even more stringent, at 5ug/m3, 15ug/m3 and 10ug/m3, respectively.

The calendar heat map, another feature of the NCAP Tracker, which gives the average PM2.5 and PM10 levels for each day, showed that several cities had continuous streaks denoting highly polluted days.

In April 2022, Delhi did not have a single day when PM2.5 met the CPCB’s 24-hour safe limit of 60ug/m3, the analysis said.

“Several continuous days of high air pollution is far more damaging to human health than a few days of very high peak pollution. As can be seen from the Delhi data, the entire second week of April reported levels above 100ug/m3,” said Ronak Sutaria, Co-Founder and CEO, Respirer Living Sciences.

In terms of NO2, which is generally generated by vehicles, power plants and industrial emissions, Delhi’s average for the four months was 41.58ug/ m3, with a peak of 51.28ug/m3 in April.

“Extremely hot weather combined with winds has led to the re-suspension of coarse particles -- a fact that is seen in the high PM10 values across most cities. The rising temperatures during the heatwave have also pushed up the demand for air conditioning resulting in higher coal consumption and this is reflected in higher PM2.5 levels,” said professor SN Tripathi, steering committee member of NCAP.