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In 2016, the WHO estimated that fine particles are responsible for more than 4 million premature deaths per year worldwide. A new study suggests that this figure needs to be reassessed: low levels of these particles could kill 1.5 million more people every year!
As Cop 27, the international conference on climate change, continues in Egypt, a new study underlines the urgent need to fight against pollution and fine particle emissions. According to researchers at McGill University in Canada, the risk of death increases even at very low levels of PM2.5 (particles with a diameter of 2.5 microns), levels below the thresholds considered potentially fatal. Result: the number of deaths attributed to this type of pollution could be considerably higher than previously thought.
1.5 million more deaths per year taking into account a low level of pollution
The researchers combined data on the health and mortality of seven million Canadians collected over a 25-year period, with information on outdoor PM2.5 concentration levels across the country.
Known for having low levels of PM2.5 outdoors, Canada is an ideal place to study the health impacts of low levels. The Canadian results were then used to complete the estimates by taking into account the risk of mortality related to outdoor PM2.5 levels.
For example, the most recent estimates from the World Health Organization from 2016 indicate that more than 4.2 million people die prematurely each year due to long-term exposure to fine particulate outdoor air pollution. (often referred to as PM2.5). A figure which would therefore be underestimated, according to Scott Weichenthal, main author of the recent article in Science Advances.
“We found that outdoor PM2.5 may be responsible for an additional 1.5 million deaths worldwide each year due to effects at very low concentrations that were not previously appreciated.”
These microscopic toxins cause many cardiovascular and respiratory diseases, as well as cancers.
Towards more ambitious directives to fight against pollution?
This Canadian study makes it possible to better assess the impact of air pollution on health on a global scale. Thanks to these discoveries, the WHO recently established ambitious new guidelines to combat air pollution linked to fine outdoor particles, halving its previous recommendations: these have recently gone from a concentration of 10 to concentrations of 5 micrograms (ug) per cubic meter.
“Even at low concentrations, polluting particles have repercussions; no threshold has been identified below which they do not affect health. This is why the limits advocated in the WHO global guidelines aim to achieve the lowest possible particulate concentrations.” vsonfirms the organization in its latest recommendations in September 2021.
Recommendations that are however not followed everywhere: the current standard of the Environmental Protection Agency of the United States of 12 ug per cubic meter is therefore now more than double the value recommended by the WHO.
Look at composition more than mass
For the authors behind this reassessment of the risks, the important thing is to go even further in the investigations, if we want to treat the planet against pollution. “One of the takeaways is that the global health benefits of adhering to the new WHO guideline are likely much greater than previously thought.” insists the author of the study.
The next steps, they say, are to stop focusing only on the mass of the particles and now start looking more closely at their composition, as some are likely more harmful than others.
A message which is, today, in the hands of the rulers gathered in Sharm el-Sheikh.
According to Dr. Liath Guetta, pulmonologist and member of our expert committee, beyond the figures, the problem is already encountered in the field: “I am not at all surprised by this new data. We know that atmospheric pollution, and more specifically these fine particles, has a very strong impact on the lungs, with what is called hyperreactivity of the bronchi, an inflammatory reaction of the bronchi to pollution, originally asthma. A phenomenon that we see more and more in everyday practice. We also know today that there is a link between fine particle pollution and cancer, pollution and respiratory assistance, or even pollution and chronic non-smoking bronchitis. This is a real subject and it is likely to be the most important subject in the years to come.“