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South City Hospital > Blog > Heat wave

You have probably heard of the phrase ‘’Heat Wave” bandied about in the news, and perhaps wondered what exactly it means. Does one hot day constitute a heat wave? And how hot is hot? Does Pakistan really get that many heat waves? If you have ever found yourself wondering about these things, then look no further.

A heat wave, as defined by the UK Met office, occurs when the daily maximum temperature exceeds the average maximum temperature by five degrees or more for five consecutive days. When we talk about the “average maximum temperature”, we are referring to the average for a specific location, and for a specific year of time, i.e we compare December temperatures to December averages, and July temperatures to July averages. So how does it need to be for it to be a heat wave? It depends upon the location.

The heat wave that killed more 1300 people in Karachi seems like a long time ago. Concerned citizens, in the heat of moment, promised to plant trees, but very little has been said regarding and how can this be done.

Effects of Heat Wave

Heat exhaustion is a relatively common reaction to severe heat and can include symptoms such as dizziness, headache and fainting. It can usually be treated with rest, a cool environment and hydration (including refuelling of electrolytes, which are necessary for muscle and other body functions).

Heat stroke is much more severe and requires medical attention – it is often accompanied by dry skin, a body temperature above 103 degrees Fahrenheit, confusion and sometimes unconsciousness.

How do Humans cope with hot weather?

The two ways to cope up with heat are by perspiring and breathing.

Is it the Heat or Humidity that is the real killer?

The humidity is a huge factor. If you have tremendously high temperatures and high humidity, a person will be sweating but the sweat won’t be drying on the skin. That’s why it’s just not heat but the combination of heat and humidity. Obviously there are thresholds for both temperature and humidity above which we see an increase in death, and it’s going to be a different temperature in Karachi than in Lahore. The other factors of temperature that causes both mortality and morbidity is the temperature that it falls to in the evening. If the temperature remains elevated overnight, that’s when we see the increase in deaths. The body becomes overwhelmed because it doesn’t get the respite that it needs.

What kind of impact does extreme, sustained heat have on the human body?

The systems in the human body that enable it to adapt to heat become overwhelmed. When a person is exposed to heat for a very long time, the first thing shuts down is the ability to sweat. We know that when perspiration is dried by the air there is a cooling effect on the body. Once a person stops perspiring, in a very short order a person can move from heat exhaustion to heat stroke.

Before someone gets full-blow heat stroke, what are body’s early reactions to excessive heat?

Heat rash and muscle cramps are early signs of people being overwhelmed by heat. If those aren’t dealt with, it can lead to more severe symptoms. Cramping of muscles can be for a number of different issues, including electrolytes not reaching to the muscles. People should be aware that their skin turning red and dry are indicators that heat is impacting them.

Who is the most vulnerable to extended high temperatures?

We know the risk factors for dying from heat and urban residents who are elderly, isolated and don’t have access to air conditioning. Obese people are at increased risk as are people on certain medications. And people who are exercising or working in the heat, who don’t meet these criteria can be at risk.

How to prevent Heatstroke?

  • Avoid strenuous activity as it raises your body’s core temperature.
  • Eat small frequent meals and drink plenty of water to keep hydrated.
  • Wear loose, light clothing which allows your body to regulate its temperature with ease.
  • Never leave children or animals in a parked car, even with the windows down.
  • Wear appropriate footwear as hot asphalt can damage your feet and raise your temperature.
  • Avoid eating foods that are high in protein as it increases metabolic heat.
  • Run cold water on your wrist every now and then to help cool the blood in the main vein.
  • Sleep on a feather or down pillow with a cotton pillowcase as synthetic materials can retain heat.
  • Replace your usual moisturisers with a cooling Aloe Vera after sun product.

What to do if you are suffering a heat stroke?

  • Drink lots of water to restore the body’s salts with ORS or Lemon Shikanjabeen. If you are fasting, immediately break your fast.
  • Take a shower and sit facing a fan to encourage evaporation and cooling down of the body.
  • In case of extremely high fever (106-108C) you can simulate cold water immersion by placing ice packs on your neck, armpits and back.
  • Fever caused by exhaustion cannot be treated with medication. Therefore, do not self-medicate. Visit a doctor right away.

We are more urban now than we have ever been in the history of human species. The intense crowding can combine with the heat island effect in big cities like Karachi.

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