Air conditioning is not needed in most global heat wave conditions

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Recommendations for the use of fans according to biophysically modeled humidity-dependent temperature threshold curves for healthy adults and healthy young people. Credit: Elsevier.

The biophysical modeling study, published in Planetary Health Lancet, defies outdated public health guidelines that discourage the use of fans at temperatures above 35 degrees Celsius / 95 degrees Fahrenheit.

Based on conducted at the University of Sydney’s thermal ergonomics lab, the researchers developed a model to determine humidity-dependent temperature thresholds at which fans could be harmful, providing conditions that exacerbate thermal stress.

“The effectiveness of a fan depends on the temperature and the temperature and our previous studies in humans have shown that only when the air temperature is very high and the humidity is extremely low can fans be harmful, ”said author, Professor Jay Jay, Professor of Heat and Health at the University of Sydney School of Medicine and the Health and Charles Perkins Center.

“In this study we were able to model the impact of different conditions based on historical meteorological data. We have shown that for younger adults the use of fans can be recommended most of the time in most regions of the world, except for those living in hot and arid areas.

“This is extremely important as air conditioning, both directly and indirectly, contributes to greenhouse gas emissions. Electric fans, on the other hand, require 30 to 50 times less energy to operate. They are more sustainable and more accessible, especially in low- and middle-income countries. “

Main conclusions

Based on meteorological data from January 1, 2007 to December 31, 2019, the researchers found that, contrary to many public health recommendations, including those of the World Health Organization (WHO), could have universally recommended the use of electric fans for effective cooling without air conditioning healthy young people during the maximum heat wave conditions in all populated cities of Bangladesh, China, Japan, Philippines, Indonesia, Canada, regions eastern United States, all of South America and Oceania and most of Europe (excluding some Mediterranean cities).

The use of the fan alone should not have been routinely recommended during the hot weather in northern India, Pakistan, the Middle East, and the southwestern regions of the United States, because it would have worsened regularly. heat stress.

Researchers point out that in some regions alternative cooling strategies may be needed for healthy older adults and, in particular, for those taking anticholinergic drugs (a class of acetylcholine-blocking drugs, a neurotransmitter) that affect sweating. the main form of cooling our bodies.

The authors conclude by demonstrating that the global guide to the use of electric fans during heat waves should be amended.

Specifically, they propose that the simplified temperature threshold for the use of the 35 ° C fan currently recommended by the WHO be increased to 39 ° C for healthy young adults, to 38 ° C for healthy adults over 65 years. and at 37 ° C for older adults take anticholinergic drugs.

The lead author, Dr. Nathan Morris, a postdoctoral researcher in environmental physiology at the University of Copenhagen, Denmark, said: “Our hope is that the public authorities will modify current heat wave recommendations to align with the latest scientific evidence. Expanding the use of these devices during heat waves can drastically reduce maximum power demand and offer a low-resource alternative for those who do not have access to air conditioning. ”


Is it safe to use an electric fan to cool down? Public health guidelines for fans are not based on evidence


More information:
Nathan B Morris et al, Use of electric fan to cool during hot weather: a biophysical modeling study, Planetary Health Lancet (2021). DOI: 10.1016 / S2542-5196 (21) 00136-4

Citation: Air Conditioning Not Needed in Most Global Heat Wave Conditions (2021, June 14) Retrieved June 14, 2021 from https://medicalxpress.com/news/2021-06-air -conditioning-unnecessary-majority-global.html

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