In parliament, this week environment ministry reiterated its stand that foreign studies that attribute deaths happening in India to air pollution are not correct because they rely on extrapolated data. The environment minister has in the past insisted that the media and public should rely on data generated in India.

“We should stop being in denial there is plenty of evidence from India,” SagnikDey, a scientist at IIT Delhi, said. He went on to list studies done by Indian authors that capture the health impacts of air pollution. There is, in fact, a 2015 Ministry of Health steering committee report on air pollution and health-related issues.

“Actions don’t need to wait for more and more evidence, there is sufficient evidence,” ManjeetSaluja from World Health Organisation said. He added that WHO figures for the disease burden attributable to air pollution are conservative estimates suggesting that the real numbers might be larger.

“WHO in its studies only focuses on health impacts that have the strongest impact and linkage that is available,” he said. “These studies are very conservative, whenever we talk about health impacts like mortality figures and disability-adjusted life years.”

There is enough data relating air pollution to acute lower respiratory disorders, Chronic Obstructive Pulmonary Disease, lung cancers and cardiovascular diseases. There is a longer list of other impacts that are still being studied like low birth weight and other cancers.

“Air pollution can cause cancer,” emerging research has shown, according to Dr SachidanandTripathi from IIT Kanpur.

The Global Burden of Disease 2015 report estimated that PM 2.5 contribute to 4.2 million deaths globally, a majority of which occur in India and China.

“These numbers are often criticised, but why this is relevant, even if you say there is some uncertainty in the calculated numbers, the most important thing is that qualitatively it can tell you how important is the pollution problem,” Dey said of the Global Burden of Disease data.