A new study suggests that low air pollution levels cause an additional 1.5 million premature deaths per year.
The World Health Organization (WHO) estimates that over 4.2 million people die prematurely each year due to long-term exposure to fine particulate outdoor air pollution (PM2.5). A recent study by researchers at McGill University now suggests that the annual global death toll from low pollution levels may be significantly higher than previously thought.
They found that mortality risk was increased, even with very low exposure to PM2.5, which had not previously been recognised as deadly. These microscopic toxins cause a range of cardiovascular and respiratory diseases, as well as cancer.
“We found that outdoor PM2.5 may be responsible for as many as 1.5 million additional deaths around the globe each year, due to effects at very-low concentrations that were not previously appreciated,” said Scott Weichenthal, an Associate Professor in the Department of Epidemiology, Biostatistics, and Occupational Health at McGill University and lead author of the study.
The full report, titled ‘How low can you go? Air pollution affects mortality at very low levels,’ was published in the journal Science Advances.
Understanding the effects of fine particulate matter
The researchers reached this conclusion by combining health and mortality data for seven million Canadians, which was gathered over a 25-year period, with information about the levels of low air pollution across the country.
Canada is a country with some of the lowest levels of outdoor PM2.5, which made it the perfect place to study its impact at low rates.
Information collected in Canada was then used to update the lower end of the scale, which is used to describe how mortality risk changes with outdoor PM2.5 levels. The results were able to show an improved understanding of how low air pollution levels affect society on a global scale.
Recently, the WHO set out ambitious new guidelines for annual average outdoor fine particulate air pollution, which cut its earlier recommendations in half, from concentrations of ten to concentrations of five micrograms (ug) per cubic metre. The current United States Environmental Protection Agency standard of 12 (ug) per cubic metre is now more than double the value recommended by the WHO.
Next steps
“One take away is that the global health benefits of meeting the new WHO guidelines are likely much larger than previously assumed,” Weichenthal stated.
“The next steps are to stop focusing only on particle mass and start looking more closely at particle composition, because some particles are likely more harmful than others. If we can gain a better understanding of this, it may allow us to be much more efficient in designing regulatory interventions to improve population health.”
