These particles are classed as PM2.5, which means particulate matter less than 2.5 micrometres in diameter – so small they can travel deep into the lungs and enter the bloodstream.

These tiny particles are treated like a foreign object by the body, which will trigger a defensive response with inflammation.

As well as irritations including sore eyes and itchy throats, short-term exposure to PM2.5 can trigger underlying conditions like atrial fibrillation, spark heart attacks and worsen conditions including asthma and chronic obstructive pulmonary disease.

Head of Monash’s Air Quality Research Unit and lead researcher Yuming Guo said the health effects of exposure to air pollution had been well documented, but this was the first study to show the global impacts of exposure to short bursts of pollution.

He said air-pollution warning systems and community action plans on high-risk days, as well as individual protective actions including face masks and limiting outdoor exposure, could help protect people.

“People should pay attention to protecting their health on these days, and wear a face mask and other measures.”

Australia and New Zealand had among the lowest level of deaths attributable to short-term PM2.5 exposure globally, with an average of 614 deaths across both countries attributable to fine-particulate air pollution each year between 2000-19.

In contrast, Asia accounted for 65 per cent of global deaths due to short-term exposure to air pollution, with an annual average of 663,889 people losing their lives to PM2.5 exposure across the region.

Within Asia, the worst region was East Asia, including China and Hong Kong, where an average of 316,290 annual deaths were recorded.

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