India isn’t ready for a deadly combination of heat and humidity

R Lakshmanan has been making frames in Chennai for two decades. He is standing for long hours outside at construction sites pounding screws on steel rods. He makes nearly 600 frames every day and ends up being the skeleton of a home. He usually works 12 hours a day. He feels lucky when he is working under a tree.

Protection has been insufficient this year. Since temperatures in March hit a sizzling 38 Celsius, the conditions have been suffocating. Lakshmanan's metal frames have been too hot to touch and have left him with blisters on his hands. He has seen construction workers collapse around him and has had to take breaks to deal with nausea and dizziness. It feels like you're living in a fireball on some days.

When faced with these conditions, our bodies call upon a well-known mechanism to keep us from overheating: sweating. As perspiration evaporates from the skin, it cools the body’s temperature. But if the air is not only hot but also already filled with moisture, less sweat can evaporate, and this safety feature fails. In India, high temperatures and humidity are increasingly combining to pose a deadly threat—one the country isn’t prepared for.

The lowest temperature that air can be cooled to via evaporation is called thewetbulb temperature. To determine it, you need to wrap the bulb of the thermometer in a wet cloth and see what the temperature is. The bulb is you, or Lakshmanan, the wet cloth is our sweating skin, and the temperature recorded is the hottest we can hope to get by sweating.

Advertisement

Physical activity becomes dangerous when wet-bulb temperatures reach 32 Celsius. Exposure to high wet-bulb temperatures can cause death. The sweating mechanism shuts down, which leads to death in 6 hours. In Lakshmanan's home city of Chennai, the wet-bulb temperature hit 31 Celsius. The district of Ernakulam in the Indian state ofKerala recorded a wet-bulb temperature of 34.6 Celsius on the same day.

A researcher in public health at the Sri Ramachandra Institute of Higher Education and Research in Chennai says that without the mechanism to rid the body of excessive heat, there are many changes in the body.

You need to raise your temperature by 3 to 4 Celsius. All other processes grind to a halt as the body tries to restore your core temperature. Circulation to the legs and feet slows. The brain won't function if there isn't enough blood flowing to it. You don't feel thirsty anymore. Soon the organs stopped working. The person goes into a coma when the brain stops communicating.

The professor of epidemiology at the Indian Institute of Public Health saysHumidity makes heat worse. It can cause catastrophic events like heart attacks and strokes, change the regulatory capacity of the kidneys, and affect the endocrine system. It's a silent killer

At least 90 deaths have been attributed to the recent heat wave in India and Pakistan according to World Weather Attribution. The wet-bulb temperature in the southern state of AP rose to 32 Celsius during the heat wave of 2015. Over 2500 people died in the heat that year.

Climate change will make such events more common. Jane Baldwin is an assistant professor in the Department of Earth System Science at the University of California, Irvine. She says that for every 1 increase in temperature, there is a 7 percent increase in humidity. Climate change has an impact on India. The Indian Ocean, with its rapid warming, is a big cause of South Asia's high wetbulb temperatures.