New Delhi, Oct 14 (PTI) Exposure to high levels of fine particulate air pollution (PM2.5) in India may have a lower than expected impact on mortality, according to the first study of its kind covering the whole country.
India has one of the highest levels of air pollution in the world, with most people living in areas where levels of fine particulate matter (PM2.5) are well above the safety limit set by the Organization World Health Organization (WHO).
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Findings from the Million Death Study (MDS), published in the journal Environmental Health Perspectives, linked PM2.5 concentrations derived from satellite measurements to deaths in more than 7,400 small areas covering a total population of 6.8 million.
Researchers quantified the relationship between PM2.5 exposures over multiple years and subsequent mortality risk, focusing on the top killers of adults: respiratory disease, heart disease, stroke and overall mortality .
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Their analyzes were adjusted for risk factors that make these diseases more common, such as smoking, urban or rural residence, and education. Since these diseases and PM2.5 tend to cluster in some areas but not others, they have also been adjusted for spatial clustering.
Analyzing more than 200,000 deaths between the ages of 15 and 69, the researchers found a 9% excess risk of death from stroke for every 10 microgram increase per cubic meter in PM2.5 exposure.
However, there were no excessive risks of respiratory or heart disease and total mortality (after excluding strokes), they said.
The study results were broadly similar across different age groups and across areas with higher or lower household solid fuel use – which itself is the main contributor to PM2.5 exposure such as as measured by satellites.
Contrary to these direct observations, previous estimates of air pollution deaths in India used complex models that assumed much higher mortality risks from PM2.5 exposure, the researchers said.
“Measuring the health effects of air pollution is complicated,” said the study’s lead author, Professor Patrick Brown, from the University of Toronto in Canada.
“There is so much to disentangle to establish whether a relationship with deaths is true, or just noise in the data. Even the modest excess risks we found for strokes could reflect the inherent uncertainty in these types of epidemiological studies,” says Brown.
The researchers noted that direct studies like the Million Death Study (MDS) are far preferable to extrapolation from models, many of which take reports from non-Indian settings and apply them to India.
Earlier models likely exaggerated the extent to which air pollution kills adults in India, they said.
“Most of the existing studies on air quality and health are carried out in high-income countries, where exposures to PM2.5 are much lower and disease patterns are significantly different from those in low-income countries. low and intermediate like India,” said the study’s co-author professor. George D’Souza, Dean of St. John’s Medical College, Bangalore, India.
“That has to change,” D’Souza said.
The results are one of many insights generated by MDS – one of the largest premature mortality studies in the world.
The study, covering deaths from 2001 to 2014, is a long-running effort to better understand the causes of death in countries like India, where the vast majority of people die at home without a death certificate.
Pioneered by Professor Prabhat Jha of the University of Toronto’s Dalla Lana School of Public Health, it has helped governments and health care providers better allocate limited public health funding.
Despite the good news, the researchers said there are many reasons to take action against air pollution in India.
“PM2.5 may not be the big killer in India as advertised, but measures to reduce PM2.5 exposure are still needed,” Jha said.
“Air pollution worsens children’s lung health and lowers quality of life, and that’s enough justification for action,” he added. PTI
(This is an unedited and auto-generated story from syndicated newsfeed, LatestLY staff may not have edited or edited the body of the content)