India's filthy air is cutting 660 million lives short by about three years - while nearly all of the country's 1.2 billion citizens are breathing in harmful levels of pollution, new research reveals.
The study, by a team of environmental economists at US universities, highlights just how extensive India's air problems have become after years of pursuing an all-growth agenda with little regard for the environment.
While New Delhi last year earned the dubious title of being the world's most polluted city, the problem extends nationwide, with 13 Indian cities now on the World Health Organisation's list of the 20 most polluted.
That pollution burden is estimated to be costing more than half the population at least 3.2 years of their lives, according to the study led by Michael Greenstone of the University of Chicago and involving economists from Harvard and Yale universities.
The most polluted regions, falling generally in northern India, are also among India's most populous.
"The extent of the problem is actually much larger than what we normally understand," said Anant Sudarshan, the India director of the Energy Policy Institute of Chicago and one of the study's co-authors.
"We think of it as an urban problem, but the rural dimension has been ignored."
Added up, those lost years come to a staggering 2.1 billion for the entire nation.
Greenstone said that while "the conventional definition of growth has ignored the health consequences of air pollution … this study demonstrates that air pollution retards growth by causing people to die prematurely."
For the study, published in Economic & Political Weekly, the authors borrowed from their previous work in China, where they determined life expectancy dropped by three years for every 100 migrograms of fine particulate matter, called PM2.5, above safe levels.
PM2.5 is of especially great health concern because, with the particles having diameters no greater than 2.5 micrometres, they are small enough to penetrate deep into the lungs.
The authors note, however, that their estimations may be too conservative because they're based in part on 2012 satellite data that tend to underestimate PM2.5 levels.
India has a sparse system for monitoring air quality, with sensors installed in only a few cities and almost unheard of in the countryside.
Yet rural air pollution remains high courtesy of industrial plants, poor fuel standards, extensive garbage burning and a heavy reliance on diesel for electricity generation in areas not connected with the grid.
Wind patterns also push the pollution on to the plains below the Himalayan mountain range.
India sets permissible PM2.5 levels at 40 micrograms per cubic metre - twice the WHO's safe level. Still, the study says, 99.5 per cent of the population is living with air pollution levels above the WHO's limit.
While India has pledged to grow its clean energy sector, with huge boosts for solar and wind power, it has also committed to tripling its coal-fired electricity capacity to 450 gigawatts by 2030.
Yet there are still no regulations for pollutants like sulfur dioxide or mercury emissions, while fuel standards remain far below Western norms and existing regulations are often ignored.
To meet its goal for coal-fired electricity, the Power Ministry says the country will double coal production to a billion tonnes within five years, after already approving dozens of new coal plants which experts say will double sulphur dioxide levels.
This article appeared in the South China Morning Post print edition as Pollution cuts 660m lives short