Extreme heat, pollution doubles fatal heart attack risk, study says

Women and older adults are especially vulnerable to fatal heart attacks when air pollution worsens during extreme heat.
Extreme heat, pollution doubles fatal heart attack risk, study says
Posted at 11:34 AM, Jul 25, 2023

The combination of extreme heat and high air pollution can nearly double a person's risk of suffering a fatal heart attack, according to a study published in the American Heart Association’s journal Circulation.

The study included an analysis of 202,000 heart attacks that occurred in the Jiangsu province of China from 2015 to 2020. The study noted that the province has four distinct seasons and major differences in pollution levels. 

When temperatures reached 82.6 to 97.9 degrees Fahrenheit for two straight days, fatal heart attacks increased by 18%. But when temperatures reached 94.8 to 109.4 degrees Fahrenheit for four straight days, fatal heart attacks increased by 74%. 

Fatal heart attacks doubled during periods of extreme heat when fine particulate pollution was above 37.5 micrograms per cubic meter.

Two-day cold snaps of 33.3 to 40.5 degrees Fahrenheit resulted in a 4% increase in fatal heart attacks. Four-day cold snaps of 27 to 37.2 degrees Fahrenheit resulted in a 12% increase. But air pollution had no effect on heart attacks when temperatures were cold, researchers said. 

“Extreme temperature events are becoming more frequent, longer and more intense, and their adverse health effects have drawn growing concern. Another environmental issue worldwide is the presence of fine particulate matter in the air, which may interact synergistically with extreme temperatures to adversely affect cardiovascular health,” said senior author Yuewei Liu. “However, it remains unknown if and how co-exposure to extreme temperatures and fine particulate pollution might interact to trigger a greater risk of death from heart attack, which is an acute response potentially brought on by an acute scenario and a great public health challenge due to its substantial disease burden worldwide.”

The research also estimates that 2.8% of fatal heart attacks are caused by the combination of extreme heat events and poor air quality. 

SEE MORE: The prolonged US heatwave continues to set uncomfortable records

The new research comes as the U.S. has encountered a hot summer and persistent smoke from Canadian wildfires. Monday marked the hottest summer day recorded in the Northern Hemisphere after decades of measuring. 

With declining air quality and increasingly brutal summers, reducing heart fatal attack risks during summer is becoming more of a challenge. 

“Our findings provide evidence that reducing exposure to both extreme temperatures and fine particulate pollution may be useful to prevent premature deaths from heart attack, especially for women and older adults,” Liu said.

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