The global health benefits of meeting the new WHO guideline are likely much larger than previously assumed.
Millions of people die prematurely each year as a result of chronic exposure to outdoor air pollution with microscopic particles causing and worsening a whole host of ailments when they are breathed in.
Air pollution is responsible for everything from cardiac arrests to severe mental ailments and from learning disabilities in children to cancers in adults. It can even affect the workings of our genes.
In all, some 2.5 billion people suffer from chronic air pollution worldwide. The World Health Organization has estimated that around 4.2 million people succumb to air pollution-related causes every year.
That is a sobering statistic, but scientists in Canada say the number might be much higher. The reason is that exposure to even very low levels of outdoor PM2.5 drives up mortality rates worldwide, according to scientists at McGill University in Toronto.
“We found that outdoor PM2.5 may be responsible for as many as 1.5 million additional deaths around the globe each year because of effects at very-low concentrations that were not previously appreciated,” says Scott Weichenthal, an associate professor in the university’s Department of Epidemiology, Biostatistics, and Occupational Health who was the lead author of a study.
The scientists reached this conclusion after combining health and mortality data for 7 million Canadians with data on outdoor PM2.5 levels nationwide over 25 years. Because Canada has low levels of outdoor PM2.5, it is an ideal place to study the health impacts of low concentrations of airborne pollutants, they explain.
“One takeaway is that the global health benefits of meeting the new WHO guideline are likely much larger than previously assumed,” Weichenthal says, referring to new recommendations that reduce concentrations of 10 micrograms (ug) per cubic metre to 5 micrograms in guidelines on the level of pollution considered acceptable.
“The next steps are to stop focussing only on particle mass and start looking more closely at particle composition because some particles are likely more harmful than others,” the scientist notes.
“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,” he adds.