Air pollution now causes more diseases in India than the use of tobacco, and accounts for one in every eight deaths, said a study published in The Lancet Planetary Health on Wednesday. The organisation said the study is the first to make estimates of deaths, disease burden, and impact on life expectancy due to air pollution in each Indian state. The study was conducted by the India State-Level Disease Burden Initiative.

India accounts for 26% of the premature deaths and disease burden globally due to air pollution even though its share in the world population is 18%, the estimates showed. Air pollution caused 12.4 lakh deaths in India in 2017, which included 6.7 lakh deaths due to outdoor particulate matter air pollution and 4.8 lakh due to household air pollution. More than half of the 12.4 lakh persons died before they turned 70.

The study says that the average life expectancy in the country would have increased by 1.7 years if the air pollution was less than the minimal level causing a loss in health, with the main hazards including lower respiratory infections, chronic obstructive lung disease, heart attacks, strokes, diabetes, and lung cancer.

More than 75% of the country’s population is exposed to outdoor air pollution levels above the safe limit of the National Ambient Air Quality Standards. The northern states are the most vulnerable, with Delhi recording the highest annual population-weighted average of PM2.5 – particles in the air with a diameter of less than 2.5 microns – in 2017, followed by Uttar Pradesh, Bihar and Haryana.

Delhi and its surrounding states have grappled with alarming levels of pollution each winter for the past few years. The air quality level in the capital had deteriorated to levels beyond “severe” a day after Diwali celebrations on November 7.

Exposure to household air pollution is another cause of concern, with the most affected states being Chhattisgarh, Rajasthan, Madhya Pradesh and Assam. “Exposure to household air pollution due to solid fuel use for cooking is decreasing in India with the increasing provision of clean cooking fuel,” said the study. “This effort needs to be sustained to address the still high levels of this exposure in several less developed states.”

India is among the four largest carbon emitters in the world along with China, the United States and the European Union. The country’s carbon emissions, set to increase by as much as 6.3% in 2018, account for 7% of the global output and are projected to rise as the “economy booms”.

The biggest sources of air pollution in the country are transport vehicles, construction activity, industry and thermal power emissions, residential and commercial solid fuel use, waste and agriculture burning, diesel generators, and manual road dust sweeping, said the study.

Indian Council of Medical Research Director General Dr Balram Bhargava said the study provided robust estimates of the health impact of air pollution in every state, which would provide a reference for improving the situation. “There is increasing political momentum in India to address air pollution,” he said. “The findings reported today systematically document the variations among states, which would serve as a useful guide for making further progress in reducing the adverse impact of air pollution in the country.”