India is in the midst of a heat wave. Temperatures across the country are 3-5°Celsius higher than they were last year. If summer sets in gradually, the body has time to acclimatise. Unfortunately, this year it has arrived abruptly and early.
Normal internal body temperature is around 37°C or 98.4°F. When temperature rises above this, the body activates several coping mechanisms. The heart beats faster and sends more blood to the skin. The blood vessels in the skin dilate, allowing heat to dissipate into the environment. Sweat glands become active, secreting a thin layer of sweat on the body. As this evaporates, it cools the body.
Although newborns have sweat glands, these are immature and inefficient. The glands don’t function efficiently until a child is about 5-6 years of age. Sweat glands also do not function well in adults over 65, especially if they are overweight, have diabetes or heart disease, or are taking medications such as diuretics or beta-blockers. These individuals are sensitive to heat and need protection.
The natural cooling mechanisms of the body can fail if there is no breeze, if the body is covered with synthetic clothing that does not absorb and wick sweat, or if the external temperature is so high that heat cannot be dissipated.
The effects of heat on the body may begin with mild irritation and discomfort. Loss of fluids and electrolytes through sweat can lead to dehydration, headaches and muscle cramps. There may be fainting, giddiness and nausea; these are
all signs of heat exhaustion. In severe cases, the body’s cooling mechanisms fail completely, resulting in heat stroke, a medical emergency in which the internal temperature rises above 104°F. This may be accompanied by loss of consciousness, convulsions and even death.
To prevent these complications, try to stay indoors as much as possible in this weather, especially during 10am to 4pm, which is the hottest part of the day. If you have to go out, wear loose cotton clothes and cover your head. Remember, it is always three degrees cooler in the shade, so stay in shaded areas whenever possible.
Keep windows open at night to let the cool air in. If possible, have an exhaust fan blowing hot air out of the room. This will keep cooler air circulating. Use fans, air coolers or air conditioning. Ideally, set the room temperature to around 27°C and use a fan to circulate the cool air, which can also help reduce electricity costs. However, if the outside temperature exceeds 40°C, a using just a fan may circulate hot air and make you feel worse. Sponging the body can help reduce body temperature. In extreme heat, if you feel you may develop heat stroke, placing ice packs in the armpits and groin can help cool the body quickly.
Bathe twice daily, using a loofah to gently clean the skin. If bathing using a bucket, add a teaspoon of salt and half a teaspoon of baking soda to the water to help prevent prickly heat. Powders marketed for prickly heat may provide temporary relief but can block skin pores and worsen the rash over time. Instead, calamine lotion or creams containing aloe vera are effective in soothing the skin. For immediate relief from itching or burning, try applying ice packs.
Hydration is crucial, as sweating leads to fluid loss. If you are already dehydrated, the sweating mechanism becomes less effective, increasing the risk of heat exhaustion and heat stroke. Aim to drink 3-4 litres of fluids daily, such as water, lightly salted lime juice or buttermilk. Avoid cola and sugary drinks, as their high sugar content makes them hypertonic and increases thirst.
The writer has a family practice at Vellore and is the author of Staying Healthy in Modern India. If you have any questions on health issues, please write to yourhealthgm@yahoo.co.in