India's notoriously poor air quality causes nearly 1.1 million premature deaths every year, almost on par with China, concluded a joint report by two US-based health research institutes

India's air now rivals China's as the world's deadliest, according to a new study published Tuesday amid warnings that efforts to curb pollution from coal won't yield results any time soon.

India's notoriously poor causes nearly 1.1 million every year, almost on par with China, concluded a joint report by two US-based health research institutes.

But where deaths linked to in China have steadied in recent years, the rate has soared in India where smog readings in major cities routinely eclipse safe exposure levels.

India has recorded a nearly 50 percent increase in premature deaths linked to PM2.5—fine particles that lodge deep in the lungs—between 1990 and 2015, the report found.

"India now approaches China in the number of deaths attributable to PM2.5," said the report by the Health Effects Institute and the Institute for Health Metrics and Evaluation.

Anti-pollution steps in China—which jostles with India for the unenviable title of world's most polluted country—has seen the number of smog-related deaths largely stabilise since 2005.

In India that number has steadily climbed from an estimated 737,400 deaths a year in 1990 to 1.09 million in 2015.

India and neighbouring Bangladesh have experienced the steepest increases in pollution since 2010 "and now have the highest PM2.5 concentrations" in the world, the report said.

Pollution in New Delhi in November reached crisis levels, with crop burning, car exhaust, dust and coal plants blamed for the record smog.

The government shuttered schools and temporarily closed a coal-fired power plant as a stop gap, but experts say the energy-hungry nation will need to do more if it's to clean the air for India's 1.25 billion people.

"Coal isn't going to go away very fast. Coal-based in the environment will always be very significant in India," Sumant Sinha, the chairman of Indian clean energy firm ReNew Power told AFP.

"Renewables are not going to be expanding fast enough for us to be able to impact that particular problem. Unless all of those (factors) are also brought under control, I don't think it's going to come anywhere close to really solving the problem."