Nearly 8000 lives are being saved in the US every year thanks to the drop in air pollution from tiny particles in vehicle exhaust fumes, according to an analysis of deaths between 2008 and 2017.
Vehicles of all types have become less polluting over the past few decades, due to more efficient engines and cleaner fuels. The emissions of some pollutants, such as carbon monoxide, have been slashed by as much as 99 per cent in the US since 1970.
But the release of particles less than 2.5 micrometres in diameter, known as PM2.5, remains a dangerous problem. These get deep into the lungs and can be absorbed into the bloodstream, contributing to deaths from conditions such as heart disease, chronic obstructive pulmonary disease and lung cancer.
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Levels of PM2.5 per kilometre driven by each vehicle have also been declining 鈥� albeit more gradually 鈥� in the US, as people upgrade to newer cars. at Harvard University and his colleagues wondered how this might have affected the number of lives lost due to PM2.5 pollution between 2008 and 2017.
Choma鈥檚 team looked to previous research that had calculated how many extra deaths a year can be attributed to PM2.5, and worked out how the figure had changed over the nine-year period.
The researchers found that, in 2017, 19,800 deaths in the US were attributable to PM2.5 in vehicle emissions 鈥� down from 27,700 in 2008.
But the fall would have been greater still if not for other factors such as people driving more kilometres a year and switching to bigger vehicles, like SUVs and minivans, which use more fuel per kilometre. Another contributor was the population getting older and being more susceptible to heart attacks and lung diseases.
If emissions per kilometre had continued at 2008 levels and everything else had stayed the same, there would have been 48,200 deaths in 2017, they found.
Choma hopes that translating the effects of air pollution into lives saved or lost will help motivate people to reduce their impact on the environment. 鈥淚f people were to move to less polluting alternatives, like public transport, hiking and electric vehicles, it would be wonderful,鈥� he says.
PNAS
