Straightforward Cooling Strategies During Heat Wave
Air conditioning is used increasingly around the world, especially in places experiencing significant economic growth. It helps people stay healthy by protecting them from heat-related deaths and enhancing productivity at work and in schools. Understanding the effects of extreme heat on individuals is crucial. In very hot weather, it is important to use low-cost, sustainable cooling methods to reduce the risk of heat-related problems and prevent heatstroke and death.
Fans are a good, low-energy alternative to air conditioning. They work well when the air temperature is below 35°C. However, in humid conditions, fans can help cool you down to 42°C, but they don't work as well on older people because they sweat less. Heat transfer between two objects (skin and air) occurs through conduction, convection (moving air), and radiation. The main process is convection. When the skin is cooler than the air, using a fan speeds up heat transfer from the air to the skin. This means the body gets hotter, not cooler. Fans can help sweat evaporate from the skin, which cools the body. However, if the air is significantly hotter than the skin, the effectiveness of sweat in cooling the body diminishes.The body keeps its temperature normal through sweating and opening up blood vessels. At high temperatures, the blood vessels open up to let more blood flow to the skin's surface, which helps the body to cool down. When the skin is fully open, it reaches about 35°C, which is the normal temperature for the body to cool down. If the air temperature is too high, the blood passing through the skin heats up, which puts more strain on the body. Very high air temperatures are usually accompanied by low humidity. Since sweat evaporates easily without air flow, using fans makes it worse and is not recommended.
Cooling methods that don't use electricity, like cooling the skin or immersing body parts in water, help reduce heat strain and dehydration without using energy. These methods are useful during power outages or in areas without electricity.
Mechanical evaporative coolers can lower air temperature in dry climates, but not in humid conditions. They can pose health risks if not maintained properly.
Simple methods, like hanging a wet sheet in front of a fan or window, offer some cooling, but are limited by smaller evaporation areas and disrupted airflow. Other ways to cool the body are ice towels on the neck or chest or drinking cold drinks. These can reduce sweating, which is important for cooling. Taking breaks during physical activity in the heat can help manage heat production. Traditional work-to-rest ratios used to mitigate health risks in hot environments may need adjustment as global temperatures rise.
Shade and less exertion during breaks can help prevent heat-related problems like low blood pressure or fainting. These cooling strategies are important for managing heat stress.
Want to stay safe in the heat? Download the Body Temperature App today and use our widget and monitor the heat index based on your location to safeguard yourself against heat-related conditions that could pose health risks.
Sources:
1. Jay O, Capon A, Berry P, Broderick C, de Dear R, Havenith G, Honda Y, Kovats RS, Ma W, Malik A, Morris NB, Nybo L, Seneviratne SI, Vanos J, Ebi KL. Reducing the health effects of hot weather and heat extremes: from personal cooling strategies to green cities. Lancet. 2021 Aug 21;398(10301):709-724. doi: 10.1016/S0140-6736(21)01209-5. PMID: 34419206.
2. Kenny GP, Jay O. Thermometry, calorimetry, and mean body temperature during heat stress. Compr Physiol. 2013 Oct;3(4):1689-719. doi: 10.1002/cphy.c130011. PMID: 24265242.
3. Ravanelli NM, Hodder SG, Havenith G, Jay O. Heart rate and body temperature responses to extreme heat and humidity with and without electric fans. JAMA. 2015 Feb 17;313(7):724-5. doi: 10.1001/jama.2015.153. Erratum in: JAMA. 2015 Apr 7;313(13):1374. PMID: 25688786.
