A study of healthy volunteers found that the combination of heat and humidity gets dangerous faster than many people realize.




Before you read, change the word in CAPITALS to fill in the blanks.


1.[HOT] ……… waves are becoming supercharged as the climate changes – lasting longer, becoming more frequent and getting just plain hotter. One question a lot of people are asking is: “When will it get too hot for normal daily activity as we know it, even for young, healthy adults?”

The answer goes beyond the temperature you see on the thermometer. It’s also about humidity. Our research shows the 2. [COMBINE] ……..  of the two can get dangerous faster than scientists 3. [PREVIOUS] ……… believed.

Scientists and other observers have become alarmed about the increasing 4. [FREQUENT] ……… of extreme heat paired with high humidity, measured as “wet-bulb temperature.” During the heat waves that overtook South Asia in May and June 2022, Jacobabad, Pakistan, recorded a maximum wet-bulb temperature of 33.6 C (92.5 F) and Delhi topped that – close to the theorized upper limit of human 5. [ADAPT] ……. to humid heat.

People often point to a study published in 2010 that estimated that a wet-bulb temperature of 35 C – equal to 95 F at 100% humidity, or 115 F at 50% humidity – would be the upper limit of safety, beyond which the human body can no longer cool itself by evaporating sweat from the surface of the body to maintain a stable body core temperature.

It was not until recently that this limit was tested on humans in laboratory 6. [SET]…….. s. The results of these tests show an even greater cause for concern.

The PSU H.E.A.T. Project

To answer the question of “how hot is too hot?” we brought young, healthy men and women into the Noll Laboratory at Penn State University to experience heat stress in a controlled environment.

These experiments provide insight into which combinations of temperature and humidity begin to become 7. [HARM] ……. for even the healthiest humans.

Each 8. [PARTICIPATE] …… swallowed a small telemetry pill, which monitored their deep body or core temperature. They then sat in an environmental chamber, moving just enough to simulate the minimal activities of daily living, such as cooking and eating. Researchers slowly increased either the temperature in the chamber or the humidity and monitored when the subject’s core temperature started to rise. (…)

When the body overheats, the heart has to work harder to pump blood flow to the skin to dissipate the heat, and when you’re also sweating, that decreases body fluids. In the direst case, prolonged 9. [EXPOSE]……. can result in heat stroke, a life-threatening problem that requires immediate and rapid cooling and medical 10. [TREAT]………. .


Now read the whole article and check your answers:


Key: 1. heat; 2. combination; 3. previously; 4. frequency; 5. adaptability; 6. settings; 7. harmful; 8. participant; 9. exposure; 10. treatment



  • supercharged – extremely powerful
  • to dissipate – to lose heat irrecoverably
  • outage – a period of time when the electricity supply to a building or area is interrupted, e.g. because of damage to the cables
  • conducive – favorable, helpful
  • to mount – to gradually increase, rise, or get bigger

Practice Makes Perfect

 Watch the video and answer the questions below:

  1. What did Douglas Casa suffer from during the 10,000 meter track race at the Empire State Games in 1985?
  2. What does it mean that it was a potentially fatal episode?
  3. What’s the difference between exertional heat stroke and classical heat stroke?
  4. What is compensable heat stress?
  5. What happens in uncompensable heat stress?
  6. What happens when leaky cells proliferate through the body?
  7. How does one diagnose an exertional heat stroke?
  8. How is it treated?



  • How do you feel about climate change?
  • Has climate change affected your country?
  • What do you think the world’s climate will be like 50 years from now?
  • Do you do anything to try to limit the effects of climate change?
  • Are “eco-friendly” cars and electrical appliances really eco-friendly?
  • Which industries need to become greener?
  • Do you think there’ll be climate change refugees in the future?
  •  Is there anything positive about  climate change?



Explore it more to create your own teaching-learning experience!


As The U.K. Burns In Extreme Heat, Where Is The Plan?







Preview in new tab