Delhi’s Terrible Air Quality

The capital’s residents know from looking out of the window every morning, or that cough that will not go, that their air quality’s bad. But new data from the Centre for Science and Environment can help understand just how bad Delhi’s air pollution is.

Earlier this year, the World Health Organization (WHO) concluded that Delhi’s air was the worst of 1600 cities in 91 countries that it measured. (Beijing is a pretty distant 76th.) This was on the basis of the most widely accepted measure of air quality – the density of PM2.5, or fine and extremely dangerous particles.

delhi air qulityThis ranking was on the basis of “ambient” or outdoor air quality, which is what our government pollution control boards measure. Here are the average readings from Delhi’s four fully functioning ambient air quality monitors for the last 40 days.

But here’s what’s even more worrying. Official monitors are not capturing what we’re really breathing, as we now know after CSE gave eight individuals portable monitors over the last two months.

Worse still, that’s just the 24-hour average of PM2.5 readings. At moments, especially late at night and early in the morning, the levels can shoot to 20 times the safe standard.

Last month, the union government launched a real-time Air Quality Index and health standards. But as CSE pointed out, no one has told us what are we to do on days that air quality goes above 250 microgrammes/ cubic metre of PM2.5, officially classified as “severe”, or with damaging health consequences even for healthy people. Beijing, meanwhile, shuts its schools and takes 80 per cent of government vehicles off the streets on such days. Time for India to start doing the same?