Air pollution exposure may cause heart attack within hour

Exposure to air pollutants – even at levels below World Health Organization (WHO) air quality guidelines – may trigger a heart attack within an hour, according to a new study from China.

The study found exposure to any level of four common air pollutants could quickly trigger the onset of acute coronary syndrome (ACS), where blood supply to the heart muscle is blocked, with the strongest risk within the first hour of exposure.

The researchers found the risks were highest among older people and when the weather was colder.

‘The adverse cardiovascular effects of air pollution have been well documented. But we were still surprised at the very prompt effects,’ said Haidong Kan, a professor in the School of Public Health at Fudan University in Shanghai, who led the study.

‘Another surprise was the non-threshold effects of air pollution,’ he said. ‘In other words, any concentrations of air pollutants (such as fine particulate matter, nitrogen dioxide, sulfur dioxide and carbon monoxide) recorded in the present study may have the potential to trigger the onset of a heart attack.’

The researchers analysed medical data for nearly 1.3 million people treated for heart attacks and unstable angina at over 2,000 hospitals in 318 Chinese cities between 2015 and 2020.

They compared hourly onset times of heart events with concentrations of fine particulate matter, coarse particulate matter, nitrogen dioxide, sulfur dioxide, carbon monoxide and ozone.

Short-term exposure to any level of fine particulate matter, nitrogen dioxide, sulfur dioxide and carbon monoxide was associated with the onset of all types of acute coronary syndrome.

As levels of the studied pollutants rose, so did the risk for heart attacks. Exposure to nitrogen dioxide was most strongly associated, followed by fine particulate matter, and was most dangerous during the first hour following exposure.

The link was strongest among adults age 65 and older with no history of smoking or other respiratory illnesses and for people exposed during the colder months.

‘The cardiovascular effects of air pollution should be a serious concern for all, including policymakers, clinicians and individuals,’ Kan said. ‘For policymakers, our findings underline the need of further tightening air quality standards, more stringent air pollution control and prompt public health response.’

Photo by Danijel Durkovic