Ambient air pollution shortens an average Bangladeshi’s life by 1.87 years, say scientists who suggest that better air quality could lead to a significant extension of human lifespan around the world.

This is the first time data on air pollution and lifespan has been studied together in order to examine the global variations to find out how they affect the overall life expectancy, reports the UNB.

Average human life is about one year shorter because of PM2.5 ambient air pollution, with lives shortened by 1.5 to 2 years in the most polluted Asian and African countries, a new study that uses data from the Global Burden of Disease Project has found.

The researchers from the University of Texas, University of British Columbia, Brigham Young University in Utah, Imperial College London and the Boston-based Health Effects Institute looked at outdoor air pollution from particulate matter (PM) smaller than 2.5 microns.

These fine particles can enter deep into the lungs, and breathing PM2.5 is associated with increased risk of heart attacks, strokes, respiratory diseases and cancer, said the report.

Currently, the World Health Organization (WHO) estimates that, worldwide, seven million people die every year from exposure to such pollution with most deaths occurring in low and middle-income countries, chiefly in Africa and Asia.

Researchers said that if PM2.5 concentrations worldwide were limited to the WHO air quality guideline concentration of 10 microgrammes per square cubic metre, the global life expectancy would be on average 0.59 year longer.

The benefit of reaching the stringent target would be especially large in countries with the highest current levels of pollution, with approximately 0.8-1.4 years of additional survival in countries such as India, Pakistan, Bangladesh and China, according to the report.

PM2.5 is released from tailpipes of vehicles, coal-fired power plants, fires, agriculture and industrial emissions. Events like dust storms and wildfires produce large amounts of the particulate matter, too.

Bangladesh placed top among 185 countries in terms of average years of life expectancy lost due to exposure to PM2.5 followed by Egypt (1.85 years), Pakistan (1.56 years), India (1.53 years), Saudi Arabia (1.48 years), Nigeria (1.28 years), and China (1.25 years).

In Bangladesh, if PM2.5 levels were to be reduced from the current 98.6 microgrammes per cubic metre to 10, 15, 25 or 35 microgrammes/cu.m, the study estimated that the potential increments in life expectancy would be between a year and about half a year (see table).

The team used data from the Global Burden of Disease Study (GBD) to measure PM2.5 air pollution exposure and its consequences in 185 countries. GBD is a collaboration of over 1,800 researchers from 127 countries, spearheaded by principal investigator Christopher J.L. Murray in the Institute for Health Metrics and Evaluation (IHME) at the University of Washington and funded by the Bill and Melinda Gates Foundation.

They then quantified the national impact on life expectancy for each individual country as well as on a global scale.

‘The fact that fine particle air pollution is a major global killer is already well known,’ said Joshua Apte, who led the study published in the journal Environmental Science & Technology Letters on August 22. The journal is published by American Chemical Society.

‘We were able to systematically identify how air pollution also substantially shortens lives around the world. What we found is that air pollution has a very large effect on survival -- on average about a year globally,’ said Apte.

‘For much of Asia, if air pollution were removed as a risk for death, 60 year olds would have a 15 per cent to 20 per cent higher chance of living to age 85 or older,’ he added.

Right now, 95 percent of the global population are exposed to levels of PM2.5 that exceed the World Health Organisation’s (WHO) recommended level, the authors write.

The study also found that death rate from air pollution has increased. They calculated 3.5 million people died globally from breathing PM2.5 in 1990 while 4.2 million were killed by the same type of air pollution in 2015.