In 1996, the air in Delhi was black with smog. The difference between then and 2016 – when the smog came back with a vengeance – was that Delhi did not know what had engulfed it. It was breathing poison. Dirty air had crept upon it. But we were oblivious to all this. There was no information about air pollution and its hazards. We merely put it down to “dark winter days”.

This is when the CSE [Centre for Science and Environment] began its work on air pollution. It was in November 1996 – now over twenty years ago – that we published Slow Murder, the deadly story of vehicular pollution in India. The book started with the investigation into the pollution-under-control (PUC) system. It asked if Delhi or any city could clean up its air by checking the tailpipe emissions of each car. Anil Agarwal, one of the authors of the book and our director, had given us a simple task: find out if PUC actually works. He called it “tailpipery”. He posed questions about what it would actually take to clean up Delhi’s air – in terms of vehicle technology, emission standards and fuel quality. This was the first such inquiry and it brought results.

For the first time the CSE was not just doing research – we had decided that this was a fight to the finish. Slow Murder would launch a campaign to fix what we had found was wrong with Delhi’s air. Remember, this was the time when air pollution was not being discussed much. It was not on anyone’s agenda yet. In fact, we were asked more than once why we were so worried about some black air.

The lieutenant governor of Delhi said this was only dust, and nothing to be worried about. The health minister said air pollution was not a health concern.

We deliberately called the book Slow Murder, as pollution did not kill instantly but instead led to the suppression of the body’s immune system, destroyed lung function or added to the cancer or cardiovascular disease burden – it was slow, but murder nevertheless. We indicted the government and industry.

We put three faces on the cover of our fortnightly, Down to Earth, November 15, 1996. They were of Jai Narain Prasad Nishad, then minister of environment and forests; TR Baalu, then minister of petroleum (there was no natural gas ministry); and Rahul Bajaj, the owner of Bajaj Motors, and at that time, India’s sole auto king.

Why? Because our research had indicted the three. Proposals for vehicular standards were being shunted from one agency to another. This was a time when India had no Bharat Stage (BS) vehicle emission standards. We had absolutely no pollution control measures. The proposal for cleaner fuel was being similarly bandied about, without any resolution. This was when fuel had 10,000 parts per million (ppm) or more of sulphur (today with BS-IV, sulphur is down to 50 ppm and this will go down to 10 ppm when we hit BS-VI).

Rahul Bajaj was on the cover of our magazine because of the extremely polluting two-stroke technology that two- and three-wheelers used. Bajaj had a monopoly on vehicles at that time – this was before the advent of the four-stroke technology. The four-stroke technology saw the rise of Hero Honda and personal car mobility, which in turn saw the rise of Maruti Suzuki and all the other companies. Our agenda was not personal. It was to bring about policies for fuel technology standards and to use this to drive out polluting vehicles. This is what we now call first-generation reform.

We were young and we were angry. But first we did what all gentrified researchers do. The then vice president of India, KR Narayanan, released Slow Murder. He agreed to do this at the vice president’s residence. This raised the book’s profile and brought attention. We followed this up with a public meeting – our very first – at the capital’s FICCI auditorium. We said: cough, wheeze, suffocate, or it’s time to take a stand. This was on 1 November 1996.

On 18 November – two weeks later—the Supreme Court issued a suo moto notice to the government of Delhi, effectively telling it to “clean up”. This case was merged with an existing matter filed by the lawyer MC Mehta. The case continues to date – writ petition number 13029 of 1985; MC Mehta versus Union of India and others.

As it happens, nothing much changed. A year went by. The automobile industry pushed against any reform and the government shuffled papers around. In 1997, we went to the public again. This time we had data to show the number of deaths caused by pollution. Our analysis (based on a World Bank model) showed that in just three years, between 1991–92 and 1995, there had been a shocking 30 per cent increase in the number of premature deaths because of pollution. Cardiologist Naresh Trehan told us that when he operated on someone, he knew where the person came from by the colour of their lungs.

If they came from Delhi, even non-smokers had black lungs, he said, showing us a photograph. And then he presented one of a resident from Himachal Pradesh, which showed pink lungs.

All this spurred action. In December 1997, Saifuddin Soz, the then Union minister for environment and forests, issued a white paper on pollution in Delhi. This became the basis of an action plan. In January 1998, the Ministry of Environment and Forests constituted the Environment Pollution (Prevention and Control) Authority (EPCA) for the national capital region (NCR). Anil Agarwal was made a member of this organization, which was unusual, as the government normally shies away from including strong civil society organizations in such authorities.

But it was an unusual time. EPCA, also known as the Bhure Lal Committee after its chairperson, who was then a serving bureaucrat in government, also continues to play a key role in pushing clean air policies.

In June 1997, the EPCA put out its first report on priority actions, in which it detailed steps that were needed to clean Delhi’s air. These included controls on diesel vehicles and the move to CNG. In July 1998, the Supreme Court’s top bench, then headed by Chief Justice AS Anand, issued directions based on EPCA’s report. It set a deadline for conversion of all three-wheelers and diesel buses to CNG.

Delhi was now on schedule for a clean-up. But even as the Supreme Court proposed, the government deposed. Powerful vested interests did not allow anything to move. Why? Because diesel had big friends.

Meanwhile, science had discovered the real pollution villain – small particulates. Till then we had only one pollutant in our lexicon – suspended particulate matter, or SPM. Now there was evidence that toxicity really resulted from the smaller particulates, then called respirable suspended particulate matter (RSPM). These were called so because they were small enough to be inhaled. RSPM was later called PM 10, and then PM 2.5, as the size of the particulate became clearer and its deadly toxicity better understood. The first study of RSPM was done in 1998. The monitoring by the Central Pollution Control Board (CPCB) showed that the level of RSPM was five times above the national twenty-four-hour standard. This was deadly. But where did RSPM come from?

By then, global research had begun to point to diesel. The size and toxicity of the particulate depended not just on how the fuel was burnt, but also on the fuel itself. Studies had found 90 per cent of the exhaust from a diesel vehicle to be below 1 micron in size; these were coated in the highly carcinogenic poly-aromatic hydrocarbons (PAH). In 1998, after a decade of work, the California Air Resources Board formally designated diesel particulates as toxic air contaminants. This was followed by studies in Japan, which discovered the most potent carcinogen to be from diesel exhaust.

This news was unpalatable to the automobile industry. They hit back. Things got messy. Really messy.

Excerpted with permission from Conflicts of Interest: My Journey through India’s Green Movement, Sunita Narain, Penguin Random House India.