Heart attack death risk doubles in heatwaves with high pollution.

Heart attack death risk doubles in heatwaves with high pollution.

How Extreme Heatwaves and Airborne Particles Double the Risk of Heart Attacks

Heart Attack during a Heatwave Study finds that people are almost twice as likely to die of a heart attack during a heatwave with particulate matter air pollution. Image credit: Amos Chapple/Stocksy.

June 2023 was Earth’s hottest month in the 174 years that scientists have been tracking global temperatures, and July appears to be every bit as torrid. More than 1,000 high-temperature records have been broken in the United States so far this summer. The scorching heat has also dried out large areas of vegetation, creating an ideal environment for wildfires to spread. As of now, there are around 1,090 active fires burning across Canada, with continuous smoke clouds of fine particulate matter being released into the air. This situation is not only affecting Canada but also potentially threatening the health of millions of North Americans.

A new study conducted in China has shed light on the dangerous combination of extreme hot weather and airborne particulate matter, such as the fine particles released by wildfires. The study revealed that these two factors can double the risk of a heart attack, also known as a myocardial infarction. The researchers focused on fine particulate matter called PM 2.5, which refers to tiny pieces of solid or liquid substances floating in the air, invisible to the naked eye. PM 2.5 consists of sulfates, nitrates, carbon, or mineral dusts and is primarily emitted from fires and wildfires.

To understand the impact of extreme heat and PM 2.5 on heart health, the researchers analyzed heart attack and temperature records for five years in China’s Jiangsu province. This region experiences four seasons, providing a wide range of high and low temperatures for the study. The findings, published in Circulation, showed that during two-day heatwaves with temperatures at or above the 90th percentile of normal weather (82.6 to 97.9 degrees Fahrenheit), the risk of dying from a heart attack increased by 18%. This risk escalated to a 74% increase during four-day heatwaves above the 97.5th percentile. Additionally, on exceptionally hot days with high levels of PM 2.5 in the air, the risk was doubled.

Cardiologist Dr. Rigved Tadwalkar, from the Pacific Heart Institute, explains that PM 2.5 particles can integrate themselves within the bloodstream, leading to inflammatory responses and oxidative stress. This process can damage blood vessels and the heart, eventually leading to atherosclerosis or plaque formation. Dr. Tadwalkar emphasizes the importance of maintaining a balance between body heat production and heat loss to prevent strain on the cardiovascular system.

While extreme heat and high PM 2.5 levels pose the greatest risk, the study also found a smaller effect when combining extreme cold with high particulate matter counts. During two-day cold snaps with poor air quality, the risk of a heart attack increased by 0.04%, which escalated to a 12% increase during three-day cold spells. Dr. Tadwalkar speculates that people tend to move indoors during extreme cold, reducing their exposure to the weather and risk.

Epidemiologist Dr. Rakesh Ghosh highlights the resilience of the human body in adapting to different temperatures. He notes that what may be a heatwave for Europeans is not necessarily unbearable for South Asians due to acclimatization. However, the impact of extreme temperatures on core body temperature remains unknown, as humans typically maintain their core temperature within a narrow range. Further research is needed to understand the effects of extreme temperature exposure on the human body.

To stay safe during high pollution days, it is recommended to stay indoors as much as possible, using air conditioning with no outside air intake. Wearing an N95 face mask can also limit the penetration of PM 2.5 particles into the body. Real-time information about PM 2.5 levels in your area can be obtained from the United States government’s AirNow website or through their free apps. Hydration is crucial during extreme heat, as the body loses water through sweating. Taking intermittent breaks in air-conditioned areas throughout the day can help regulate body temperature, while wearing light and loose clothes and wide-rim hats can provide additional protection.

As extreme heatwaves and wildfires become more common due to climate change, it is essential to prioritize the health and safety measures necessary for individuals to protect themselves from the combined risk of extreme heat and airborne particulate matter. Understanding the impact of PM 2.5 on heart health and taking appropriate precautions can help reduce the likelihood of heart attacks and other cardiovascular events in the face of increasingly challenging climatic conditions.