Tamil Nadu’s capital Chennai was the only city among the ten ‘non-attainment cities’ in the country that recorded particulate matter (PM) 2.5 and PM10 levels within safe limits, as prescribed by the Central Pollution Control Board (CPCB), during the summer months.
This was part of an analysis of pollution data collected by the National Clean Air Programme (NCAP) tracker from ten cities across the country— Agra, Bengaluru, Chandigarh, Chennai, New Delhi, Kolkata, Jodhpur, Mumbai, Lucknow and Patna— between March and June.
The analysis showed that all other cities in the study recorded levels higher than permissible limits, and only Kolkata and Bengaluru joined Chennai in May. Chennai was also the only city that had PM10 levels within safe limits during April. The cities were chosen because they were classified as non-attainment cities, whose air did not meet the national ambient air quality standards of 2011 to 2015. The NCAP was launched for such cities, seeking to bring a 20% to 30% reduction in levels of PM2.5 and PM10 particles by 2024.
The breaching is a clear indication that air pollution is not just a winter problem, as commonly perceived, and more heat means more pollution. The CPCB’s annual average permissible limits for PM2.5, PM10 and NO2 are 40 microgram/metre cube, 60 microgram/metre cube and 40 microgram/metre cube respectively. However, the World Health Organisation’s (WHO)’ safe limits are much lower at 5 microgram/metre cube, 15 microgram/metre cube and 10 microgram/metre cube for the three pollutants respectively.
Ronak Sutaria, co-founder and CEO, Respirer Living Sciences, said, “Several continuous days of high air pollution is far more damaging to human health than a few days of very high peak pollution.
While regulatory standards are based on 24 hour and annual means, it is evident that weekly averages and the cumulative load of air pollution need to be tracked closely too.”
Unlike winters, the atmospheric boundary layer that keeps pollutants close to the surface is much higher during summer, and gives more space for the pollutants to disperse. If air pollution levels are higher despite this, it is a cause for concern.
Prolonged exposure to high pollution levels throughout most of the year impacts human health. According to a recent study commissioned by the Energy Policy Institute (EPIC) at the University of Chicago, air pollution has shortened life expectancy in New Delhi by up to 10 years and across the country by five years.
Mahesh Palawat, VP, Meteorology and Climate Change, Skymet Weather, said, “This year, pre-monsoon rains were almost nil during March and April. Heatwave conditions also started to affect many parts of the country as early as the second week of March. Usually, during such continuous dry spells, air pollution increases as rains don’t wash away the pollutants, and the dust particles which constitute PM10 continue to remain suspended in the lower levels of the atmosphere.”
Over the years with the NCAP, it is clear that the government too acknowledges the air pollution crisis in the country and policies are being put in place.
Recently, the New Delhi government also announced that the national capital would get a summer action plan to deal with high air pollution. Air pollution is one of the sectors that the Mumbai Climate Action Plan will focus on.
Public health experts from Healthy Energy Initiative (India) contested the claims and pollution levels in the report. Their contention was that the some areas of North Chennai were worst affected by dust and heavy metal pollution owing to the high concentration of polluting industries, oil refinery and thermal power plants in Manali and Ennore. They also laid stress on the need for more monitors to be placed in the city.