When Delhi Became The World's Pollution Capital
The Troubling Discovery: In May 2014, the World Health Organization released its Ambient Air Pollution database covering nearly 1,600 cities across 91 countries. The report delivered shocking news for India's capital. Delhi had the highest concentration of dangerous PM2.5 particulate matter of any major city in the world. PM2.5 refers to tiny particles less than 2.5 microns in diameter, about 25 to 100 times thinner than a human hair. These microscopic particles penetrate deep into the lungs and can enter the bloodstream, causing serious respiratory and cardiovascular diseases. Delhi's air contained PM2.5 concentrations of 153 micrograms per cubic meter, while PM10 particles measured 286 micrograms per cubic meter. Both levels exceeded permissible safety limits by enormous margins.