Researchers Identify Temperature, Humidity Combinations That Stress the Heart

Article

The findings could inform revisions to safety guidelines and policies that help protect people with cardiovascular issues during heat waves.

New research findings show that cardiovascular strain begins at lower temperature and humidity levels than those that increase the body’s core temperature, according to findings presented at the American Physiology Summit.

Credit: New Africa - stock.adobe.com

Credit: New Africa - stock.adobe.com


Researchers have long known that more heart attacks occur during extreme heat events because of cardiovascular strain. This will become an increasingly common issue as global climate change results in more extreme weather events, including heat.1

“We wanted to establish the critical combinations of temperature and humidity that cause a continuous rise in heart rate—indicating cardiovascular strain—in healthy adults,” said the study’s first author Rachel Cottle, a doctoral candidate at Pennsylvania State University (PSU), in a press release. “We plan to use this as a baseline before identifying the conditions that are dangerous for more vulnerable groups such as older men and women.”1

The study was part of the PSU Human Environmental Age Thresholds (HEAT) project led by W. Larry Kenney, PhD, FAPS. It included 45 participants in their 20s who slowly walked on a treadmill or performed activities simulating minimal activities of daily living, all while inside environmental chambers that produced either warm and humid or hot and dry environmental conditions.1

“Our findings can help determine when alerts are needed to advise people to limit activity, stay hydrated, and remain in the shade or air conditioning as much as possible,” Cottle said in the press release. “They could also help determine when organized sporting events should be postponed, cooling centers should be implemented, or outdoor workers should take extra breaks.”1

According to the study, the investigators found that during minimal activity in warm and humid environments, cardiovascular strain increased when temperatures reached 95 degrees Fahrenheit and relative humidity was 65%, whereas increases in core temperature occurred at 95 degrees and 73% relative humidity. During slow walking in warm and humid environments, cardiovascular strain increased at 95 degrees and 52% relative humidity, whereas core temperature increased at 95 degrees and 58% relative humidity.1

In hot and dry environments, cardiovascular strain rose at temperatures above 113 degrees and 19% relative humidity, whereas core temperature increased at 118 degrees and 17% relative humidity during minimal activity. During slow walking in the same conditions, increases in cardiovascular strain occurred at 104 degrees and 25% relative humidity, and increases in core temperature occurred at 109 degrees and 22% relative humidity.1

“If we know that there’s a heat wave coming and it’s going to be 100 degrees and 70% relative humidity, which is above those limits that we saw for cardiovascular strain, then we can say, ‘Ok, if you can stay in air conditioning as much as possible, then do that. Make sure you’re adequately hydrated,” Kenney explained in an interview with the American Physiological Society.2

REFERENCES

  1. Staying Safe When It’s Hot: Study Identifies Temperature-humidity Combinations that Stress the Heart. News release. American Physiological Society. April 18, 2023. Accessed April 17, 2023.
  2. Study Identifies Temperature-humidity Combinations that Stress the Heart. YouTube. April 12, 2023. Accessed April 17, 2023.
Related Videos
Image credit: Dr_Microbe | stock.adobe.com
Home Diabetes Treatment - Image credit: Dglimages | stock.adobe.com
Image credit: Azee/peopleimages.com | stock.adobe.com
Cropped view of senior man playing with puzzles on table- Image credit: LIGHTFIELD STUDIOS | stock.adobe.com
Breast cancer with lymphatics, medically 3D illustration | Image Credit: Axel Kock - stock.adobe.com
Woman with pink ribbon on color background. Breast cancer awareness concept | Image Credit: Pixel-Shot - stock.adobe.com
Pharmacy, medicine and senior woman consulting pharmacist on prescription. Healthcare, shopping and elderly female in consultation with medical worker for medication box, pills or product in store- Image credit: C Daniels/peopleimages.com | stock.adobe.com
View in microscopic of pathology cross section tissue ductal cell carcinoma or adenocarcinoma diagnosis by pathologist in laboratory | Image Credit: arcyto - stock.adobe.com
A female doctor sits at her desk and talks to a female patient while looking at her mammogram | Image Credit: lordn - stock.adobe.com
© 2023 MJH Life Sciences

All rights reserved.