CHENNAI: Chennaiites are breathing toxic air for at least 100 days in a year, although it may not always be visible except when it shows up as smog. The concentration of harmful particulate matter (PM) in the city is several times higher than the prescribed limit.
An analysis of the Central Pollution Control Board data of the last four years establishes that levels of PM 2.5 - the most harmful pollutant - has shot up to as high as 995 ug/m3 on many occasions. The WHO prescribes 25 ug/m3 as safe limit, while India has fixed a standard of 60 ug/m3.
PM 2.5 particles are 20 times smaller than the width of human hair. On breathing this air, these ultra-fine particles are quickly absorbed into the bloodstream, penetrating deep into the respiratory and circulatory systems. This air fills our lungs, affecting our ability to breathe properly and reducing our life expectancy. Even short-term exposures to these particles can trigger symptoms of asthma and cause respiratory or heart issues.
Chennai by no means breathes ‘clean air’. If you think Chennai’s poor air quality earlier this month was a freak show and one-off incident, you are mistaken.
An analysis of the Central Pollution Control Board (CPCB) data shows that for 980 days (Manali-567 days, Alandur-235 and Velachery-178), people have been exposed to polluted air where levels of PM 2.5 – the most harmful pollutant – has shot up to as high as 995 ug/m3. This year alone, the CPCB data shows air quality in Manali station breached the permissible limit for 106 days. The data is not available for 71 days. Since November 8, a week after the media started writing about deteriorating air quality in Chennai, the indicator at Manali station has been turned off without any explanation. It is not November, rather February and March that were the worst months in Alandur, which recorded four severely polluted days – February 13, when PM 2.5 levels reached 392 ug/m3, February 25 (504 ug/m3), February 28 (423 ug/m3) and March 1 (459 ug/m3).
Even Velachery station near IIT-Madras reported 44 poor air quality days ranging from moderate to severe, spread across the year and the real-time monitor relayed “no data” on 89 days. This shows pollution spikes are not incidental or rare for Chennai.
‘CPCB data not enough’
Senior officials of Tamil Nadu Pollution Control Board (TNPCB) told Express that data from three monitors of CPCB was not enough to draw conclusions on air quality of Chennai. “Manali is an industrial area and pollution spikes are common. The pollution control board has set up five continuous ambient air quality monitoring stations in the city and will shortly be linked to Air Quality Index (AQI), which will give more realistic values,” an official said.
But environmentalists said the authorities are simply trying to hide behind their own inefficiency. Ronak Sutaria, founder of UrbanSciences, said, in Delhi, there were about 40 government monitors and a bunch of private low cost monitors. “In all, Delhi gets data from about 400 points. The PCBs of other cities should also recognise the problem and beef-up monitoring mechanism.”
Shweta Narayanan of Healthy Energy Initiative (India) said the authorities cannot say Chennai is not polluted when they do not have data. “We have been conducting studies from 2016. The latest study was conducted in May-July this year carrying out sampling at 15 sites across Chennai using low cost monitors. The analysis show levels of PM 2.5 in all 15 locations were above statutory limits. It ranged from 70.46 ug/m3 to 187.36 ug/m3.”
The samples showed presence of heavy metals like manganese, nickel, lead and crystalline silica.