Staying cool when the heat rises
12 Feburary 2010
It may seem a little early in the year to be worrying about the heat, but with increasing concerns about climate change and recent deadly heat waves, the health effects of hot weather are fast becoming a global public health challenge for the 21st century.
Online this week in the 'Lancet', Dr Shakoor Hajat of the London School of Hygiene and Tropical Medicine and colleagues review the evidence behind the advice that public bodies give to help people protect themselves against hot weather.
Much of the advice is based on common sense - wear lightweight, loose fitting clothing, drink regularly without waiting for thirst, avoid or reduce physical activities and avoid going out during the hottest part of the day - but the evidence behind some of the advice is conflicting.
For example, the authors question the merits of other commonly given advice, such as avoiding the consumption of alcohol. They say: "This advice is probably overemphasised, and should distinguish between moderate consumption of low-alcohol beverages and spirits, which should be avoided."
Regarding the use of prescription drugs during extreme heat, the authors say: "Drug use is often cited in the plans as a potential risk factor for heat-related illness, but practical advice for appropriate action or adjustment of treatment regimens is rarely provided to readers, other than to check with your doctor. The extent to which health professionals are informed about how to adjust the doses of drugs for a patient during hot weather is unclear."
Drugs that could cause problems in intense heat include diuretics - which increase urination and are used to treat heart failure and high blood pressure among other conditions - since water loss from the body can lead to decreased blood volume, low blood pressure, and to rapid heart rate and falls. Care should also be taken with antipsychotic drugs since these can affect sweat production.
Elderly people are of particular concern when the temperature rises. The authors call for more research to look at how elderly people can strengthen their physiological defences through acclimatisation. They say: "Although advice to stay in an air-conditioned environment is well supported by evidence, avoidance of outdoor temperatures and strenuous exercise might deprive elderly individuals of the opportunity to train their sweat glands". They suggest drawing on experimental evidence available from sports, military, and occupational settings, in which techniques to make activity during hot weather safe have been identified, such as pre-cooling the body before activity.
The authors conclude: "With rises in temperatures expected in the coming decades, use of evidence-based health protection during hot weather by the general public and public health practitioners will have a key role in determining the effects of heat burdens in the future."
Image: Sun, heat, dust, playa. Credit: Lars_Zapf on Flickr
Reference
Shakoor Hajat et al. Health effects of hot weather: from awareness of risk factors to effective health protection. Lancet 2010 [Epub ahead of print].
