Explained | What has Delhi done over the decades to combat air pollution? 

How far back does Delhi’s air pollution problem go? What policy measures have been taken over the decades?

The story so far: Last week, Delhi was once again covered in a cascading haze of smog— witnessing very poor air quality, sticking to the trend that has existed during winter months for some years now. The last stage of the Graded Response Action Plan (GRAP) was activated and then revoked, primary schools closed, and the debate about the “main culprit” for the polluted air was rekindled.

As the situation becomes an annually recurring one, here’s a look at how far back it goes and what policies have been adopted by the Centre and Delhi’s elected governments over the years.

While civil society and media attention for Delhi’s air pollution problem and high PM2.5 concentrations peaked in the last decade, with annual episodes of pollution induced smog setting over the Capital in winter months, air pollution has been on the rise since the 1990s.

In March 1995, the Supreme Court, while hearing a plea by environmentalist and lawyer M.C. Mehta about Delhi’s polluting industries, noted that Delhi was the world’s fourth most polluted city in terms of concentration of suspended particulate matter (SPM) in the ambient atmosphere as per the World Health Organisation’s 1989 report. The Court took note of two polluting factors— vehicles and industries, and in 1996 ordered the closure and relocation of over 1,300 highly-polluting industries from Delhi’s residential areas beyond the National Capital Region (NCR) in a phased manner. Multiple brick kilns were also directed to be relocated outside city limits.

In 1996, Mr. Mehta filed another public interest litigation alleging that vehicular emissions were leading to air pollution and posed a public health hazard. In the same year, a report about Delhi’s air pollution by the Centre for Science and Environment made the apex court take suo motu action, issuing a notice to the Delhi government to submit an action plan to curb pollution. Both matters were later merged.

Later that year, the Delhi government submitted an action plan. The Supreme Court, recognising the need for technical assistance and advice in decision-making and implementation of its orders, asked the Ministry of Environment and Forests (now the Ministry of Environment, Forests, and Climate Change- MoEFCC) to establish an authority for Delhi, leading to the creation of the Environmental Pollution Control Authority of Delhi NCR (EPCA) in 1998.

The EPCA submitted its report containing a two-year action plan in June of that year and the Supreme Court subsequently ordered the conversion of the whole Delhi Trasport Corporation (DTC) bus fleet, taxis, and autos to Compressed Natural Gas (CNG), and the phasing out of all pre-1990 autos. Other measures between the late 1990s and early 2000s included the complete removal of leaded petrol, removal of 15 and 17-year-old commercial vehicles and a cap of 55,000 on the number of two-stroke engine auto rickshaws (which reports at the time said were contributing to 80% of pollution in the city). Coal-based power plants within Delhi were also later converted to gas-based ones.