Heatwaves and air pollution double risk of heart attack, new study claims

Researchers have claimed that soaring heat and high levels of fine particulate matter in the air could significantly increase the risk of death from heart attacks, potentially doubling the danger.

The study, published on Monday in the American Heart Association's journal Circulation, involved an extensive analysis of over 200,000 heart attack deaths occurring between 2015 and 2020 in a Chinese province characterised by four distinct seasons, varying temperatures, and pollution levels.

The researchers examined the association between extreme weather conditions, air pollution and fatal heart attacks.

The results unveiled a troubling connection: days with extreme heat, extreme cold or elevated levels of fine particulate matter air pollution were all "significantly associated" with a higher risk of death from heart attacks. Particularly concerning were days with a combination of both extreme heat and high air pollution levels, which presented the greatest risk. Women and older adults were identified as particularly vulnerable groups.

Senior author of the study, Dr. Yuewei Liu, an associate professor of epidemiology in the School of Public Health at Sun Yat-sen University in China's Guangzhou highlighted the increasing concern about the health effects of extreme temperature events worldwide. Additionally, the presence of fine particulate matter in the air, when combined with extreme temperatures, was found to have an adverse impact on cardiovascular health.

The researchers found that during two-day heatwaves with heat indexes at or above the 90th percentile, ranging from 28.1 to 36.61 degree Celsius, the risk of a fatal heart attack was 18 per cent higher. However, the risk surged to 74 per cent higher during four-day heatwaves with heat indexes at or above the 97.5th percentile, ranging from 34.8 to 43 degrees.

Moreover, when fine particulate pollution levels exceeded 37.5 micrograms per cubic meter during four-day heatwaves, the risk of heart attack death was found to be twice as high. It's important to note that the World Health Organisation (WHO) recommends no more than 15 micrograms per cubic meter for just 3-4 days per year, to put this in perspective.

Fine particulate matter, despite their size being less than 2.5 microns, can have severe health implications as they can be inhaled deeply into the lungs. Common sources of these pollutants include car exhaust, factory emissions and wildfires, all of which can irritate the lungs and blood vessels around the heart.

Dr. Liu highlighted the significance of the findings, stating that efforts to reduce exposure to both extreme temperatures and fine particulate pollution could be crucial in preventing premature deaths from heart attacks, especially for women and older adults.