New Delhi, Sept. 11: The people of Calcutta and Mumbai may on average live three years longer with an improvement in air quality to meet World Health Organisation standards, new research suggests. For Delhi residents, the gain could be nine years.
A study released today by collaborating scientists in China, Israel and the US has found that every additional 10 micrograms per cubic metre of tiny particulate matter, sized 10 microns or less, reduces life expectancy by about six months.
The researchers, who used a unique social setting in two regions of China to study air pollution and life expectancy, have discovered a link they say could be applied to determine life expectancy gains in other countries with improved air quality.
They found that China's decades-old policy to provide free coal to a region north of the Huai river had led to higher pollution in the north of the river than its south. Also, people north of the river lived about three years less than those in the south, the increase in the death rates linked to air pollution-driven heart disease, stroke, lung cancer or respiratory illness. The findings appeared today in the journal Proceedings of the National Academy of Sciences.
"Particulates' impacts on the life expectancy in many parts of the world are similar to the effects of every man, woman and child smoking cigarettes for several decades," said Michael Greenstone, director of the Energy Policy Institute at the University of Chicago, who led the study.
The scientists have used their results from China to develop an air quality-life index that allows them to determine the gain in life expectancy in different parts of the world if tiny particulate matter (PM) is reduced to safe or permissible levels as prescribed by national standards or the WHO.
Several studies have suggested that the air pollution levels over several cities and towns in India are among the highest in the world.
Calculations based on the air quality-life index suggest that people in the National Capital Region could expect to live nine years longer if air quality met WHO standards. People in Calcutta and Mumbai would gain over three years, and those in Patna and Agra, seven and eight years, respectively.
"Such an analysis helps build a stronger case for why it is important for India to take action," said Anumita Roychowdhury, executive director for research and advocacy at the New Delhi-based non-government Centre for Science and Environment, who was not associated with the study.
"Earlier studies have tried to estimate premature deaths; here the focus is on gains to life expectancy," Roychowdhury said. "At the individual level, a gain in life expectancy is also likely to mean less expenses on treating air pollution-related illnesses."
While many earlier studies had demonstrated the adverse impacts of air pollution on health, scientists had until now been unable to use all the accumulated evidence to determine the effects of persistence exposure to pollution on a person's life expectancy.
Greenstone and his colleagues examined air pollution data from 154 cities in the north and south of the Huai river between 1981 and 2012 and sought to correlate these with mortality data from 2004 to 2012. They found that PM air pollution was 46 per cent higher in the north because of the heavy burning of coal.
The shorter life spans north of the river owed almost entirely to increases in heart disease, stroke, respiratory illness and lung cancer.
"The air quality-life index allows people around the world exposed to high air pollution levels to estimate how much longer they would live if they breathed cleaner air," Greenstone said. "It's a tool that will also allow policy-makers to appreciate the gains to health through improvements in air quality."