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Lockdown-driven air pollution cuts lower heart attack risk

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The number of people in the US suffering from heart attacks fell during the Covid-19 lockdowns, as air quality improved due to the reduction in the number of cars on the road, a study has found.

“Reducing pollution is not only helpful for the environment it may also have significant health benefits at the population level such as preventing heart attacks,” said lead author Sidney Aung, a fourth-year medical student at the University of California.

Heart disease is the leading cause of death in the US and previous research has shown that environmental conditions such as air pollution can increase the risk of it occurring. In 2017, exposure to particulate air pollution was estimated to be associated with more than seven million premature deaths and the loss of 147 million healthy life-years globally.

Across the period analysed in this study (Jan 2019-April 2020), the number of severe heart attacks dropped substantially in association with declining ambient pollution levels.

According to an international analysis, IQ Air’s 2020 World Air Quality Report, global lockdown measures to slow the spread of Covid-19 resulted in healthier air around the world in 2020.

The report is based on the world’s largest database of ground-based air pollution measurements. Less air pollution was noted, particularly during the initial period of the lockdown when people were ordered to shelter in place, closing schools and businesses and reducing vehicle and airplane traffic.

Overall, 60,722 heart attacks occurred during the study. With each 10 µg/m3 (micrograms per cubic meter) drop in PM2.5 the number of heart attacks decreased by six per cent, translating to 374 fewer heart attacks per 10,000 person-years.

“This study highlights the importance of reducing air pollution, which could, in turn, prevent heart attacks,” Aung said. “We also hope our study may influence other investigators to pursue similar research to corroborate these results or to investigate other forms of air pollutants outside of particulate matter 2.5 that may have also declined during the pandemic lockdowns.”

Other studies have made similar links – for example a rapid drop in acute heart attacks occurred after public smoking bans reduced second-hand smoke exposure. However, it is unclear what connections exist between the pandemic lockdown and fewer heart attacks.

“It is also possible that other things were going on last year to reduce heart attack triggers – fewer exertional activities or other stressors, for example, that were also a result of the Covid lockdowns,” said Professor Joel D. Kaufman of the University of Washington. “If it turns out that we can meaningfully link a reduction in traffic-related air pollution during Covid lockdowns to a reduction in heart attacks, it points the way toward a major change that could help to reduce the burden of heart disease. We know how to reduce air pollution concentrations and have seen that it is possible.”

“This could reinforce the benefits of air pollution reduction as a cost-effective way to improve health,” he said. “It also means that reducing fossil fuel combustion, which we need to do anyway to combat climate change, may yield tremendous health benefits now, even if the climate benefits take years to accrue.”

In September, the WHO tightened its air quality guidelines in a bid to cut air pollution deaths.

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