The History Of How Delhi’s Air Pollution Got So Toxic


It was April 1999 and I was at my first press conference. It had been organized to tell the world that we had received a legal notice from Tata Motors for a whopping Rs 100 crore. This was over an article that my late colleague Anil Agarwal and I wrote, stating about harmful toxins emitted by diesel vehicles that were dangerous to human health.

My exact message was: Diesel vehicles emit fine particles. They were named back then as PM 10 and are now known as PM 2.5—simply because measuring devices have improved over the years. It has been shown conclusively that because of their small size, these particles can penetrate deep into our lungs and enter our bloodstream, leading to cardiac and respiratory problems. The World Health Organization (WHO) had classified these particles as “likely carcinogen” (since then, it has upgraded the threat to “carcinogen”). Our conclusion was: Cars should not use diesel. Buses should shift to compressed natural gas (CNG), which emits much lower levels of PM 10 and PM 2.5. The government should rapidly and urgently clean up the quality of fuel and improve vehicle technologies.

Our conclusion was: Cars should not use diesel

My colleagues at the CSE (Centre for Science and Environment) had spent over a year trying to understand the cause of pollution in the city…there had been an explosion in the number of vehicles on the road—a phenomenon driven by the easy availability of the affordable Maruti cars.

This, combined with the fact that there was absolutely no standard for the quality of fuel or limits on vehicle emissions, meant that the air of the national capital was toxic.