Heat, Ozone Combo Hikes Heart Attack Risk

Study: Environmental Duo Threatens Cardiovascular Health, Especially for Women and Younger Adults

A new study reveals that simultaneous exposure to ozone pollution and high temperatures elevates the risk of acute myocardial infarction (MI) for adults within the United States. The research highlights the dangers of these combined environmental stressors, even at moderate levels, underlining the need for timely patient counseling to mitigate cardiovascular risks.

Joint Exposure Findings

Researchers from Yale School of Public Health, led by Lingzhi Chu, discovered that a combination of ground-level ozone (60 ppb) and temperatures around 90-95°F increased the risk of a heart attack by 33% compared to cooler, low-ozone days. Even with moderate conditions, such as ozone levels at 50 ppb and temperatures at 70°F, the risk increased by 15%.

“The lag of effect means clinicians need to pay close attention to high-pollution and hot days in real time,” stated Lingzhi Chu. “Clinicians should emphasize to younger patients that moderate levels still pose risks” to cardiovascular health.

“This study is important because it focuses on a younger age group that is often overlooked in cardiovascular research,”

—Mary Johnson, Research Scientist

The study indicates women are more vulnerable on days with both high ozone and high temperatures, while men experience heightened risks when either factor is elevated. These exposure-response pattern differences by sex were statistically significant (P = .016).

Prevention and Guidance

Chu recommends prevention strategies clinicians can share with patients, including adjusting outdoor activity timing, staying hydrated, and using cooling methods like fans or air conditioning. She suggests framing mitigation as simple behavior changes rather than dramatic life alterations to avoid overwhelming patients. The American Heart Association reports approximately 800,000 heart attack cases each year in the US.

Johnson, from the Harvard T.H. Chan School of Public Health, agrees with the findings. She highlights that clinicians need to understand the role of environmental factors in cardiovascular health.

“Just because you’re young and healthy does not necessarily rule out the risk of a cardiac event,” she said. “Especially if there’s a combination of poor air quality and elevated temperature.”