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Ng Teng Fong General Hospital
Jimmy Lee’s glasses are foggy as he works in the sweltering heat
Millions of people worldwide could be exposed to dangerous levels of heat stress, a dangerous condition that can lead to organ closure.
Many live in developing countries and do jobs that expose them to life-threatening conditions.
These include being outdoors on farms and construction sites or indoors in factories and hospitals.
Global warming will increase the chances of summer conditions that may be “too hot for humans” to work.
When we met Dr. Jimmy Lee, his glasses were misted and sweat was dripping from his neck.
An emergency physician, he works in the sweltering heat of tropical Singapore to care for patients with Covid-19.
There is no air conditioning, a deliberate option to prevent the virus from spreading, and he notices that he and his colleagues become “more irritable, shorter with each other.”
And your essential personal protective equipment to prevent infection makes things worse by creating a sophisticated ‘microclimate’ under the multiple layers of plastic.
“It really hits you the first time you get in there,” says Dr. Lee, “and it’s really awkward for an entire eight-hour shift: it affects morale.”
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Ng Teng Fong General Hospital
Working in PPE in a tropical climate can be extremely uncomfortable
He realizes that one danger is that overheating can slow down his ability to do something that is vital for medical staff: making quick decisions.
Another is that they can ignore the warning signs of what is called heat stress, such as fainting and nausea, and continue working until they collapse.
What is heat stress?
It is when the body is unable to cool down properly that its core temperature continues to rise to dangerous levels and key organs can shut down.
It occurs when the main technique to remove excess heat, evaporation of sweat on the skin, can not take place because the air is too humid.
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And as Dr. Lee and other doctors have discovered, the waterproof layers of personal protective equipment (PPE), designed to prevent the virus from entering, have the effect of preventing sweat from evaporating.
According to Dr. Rebecca Lucas, who researches physiology at the University of Birmingham, symptoms can range from fainting and disorientation to cramps and kidney and intestinal failure.
“It can become very serious as it overheats, and in all areas of the body.”
How can we detect it?
A system known as Wet Bulb Globe Temperature (WBGT) measures not only heat but also humidity and other factors to provide a more realistic description of conditions.
In the 1950s, the U.S. Army used it to develop guidelines to keep soldiers safe.
When the WBGT reaches 29 ° C, for example, the recommendation is to suspend exercise for anyone not acclimatized.
However, that is the level that Dr. Lee and his colleagues regularly experience at Ng Teng Fong General Hospital in Singapore.
And at the top of the scale, when the WBGT registers 32C, the United States says strenuous training should stop because the risk becomes “extreme.”
But such high levels have recently been recorded in Chennai hospitals in India by Professor Vidhya Venugopal of Sri Ramachandra University.
He has also found workers in a saline bearing a WBGT that rises to 33 ° C during the day, at which time they have to seek refuge.
And at a steel plant, a fierce level of 41.7 ° C was recorded, and workers are among the most vulnerable to what she calls “the great heat.”
“If this happens day after day, people become dehydrated, there are cardiovascular problems, kidney stones, heat exhaustion,” says Professor Venugopal.
What impact will climate change have?
As global temperatures rise, there is also likely to be more intense humidity, meaning more people will be exposed to more days in that dangerous combination of heat and humidity.
Professor Richard Betts of the UK Meteorological Office has run computer models suggesting that the number of days with a WBGT above 32C will increase, depending on whether greenhouse gas emissions are reduced.
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The U.S. Army developed heat stress guidelines to keep your soldiers safe
And it explains the risks to millions of people who already have to work in the challenging combination of extreme heat and high humidity.
“Humans evolve to live in a particular range of temperatures, so it is clear that if we continue to cause temperatures to rise worldwide, sooner or later the hottest parts of the world could begin to see conditions that are simply too high for us”.
Another study, published earlier this year, warned that heat stress could affect 1.2 billion people worldwide by the year 2100, four times more than now.
What solutions are there?
According to Dr. Jimmy Lee, “it is not rocket science.”
People need to drink plenty of fluids before starting work, take regular breaks, and then drink again when they rest.
Her hospital has started taking “frozen” semi-frozen drinks to help staff cool down.
But he admits that avoiding heat stress is easier said than done.
For him and his colleagues, going to rest involves the painstaking process of changing the PPE and then returning to a new set of equipment.
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There’s also a practical problem: “Some people don’t want to drink to avoid having to go to the bathroom,” he says.
And there is a professional desire to continue working regardless of difficulties so as not to disappoint colleagues and patients in a time of crisis.
People who are highly motivated may be at increased risk for heat injury, says Dr. Jason Lee, an associate professor of physiology at the National University of Singapore.
It is a leading member of a group specializing in the dangers of excessive heat, the Global Heat Health Information Network, which has developed guidelines to help doctors cope with Covid-19.
It is headed by the World Health Organization (WHO), the World Meteorological Organization (WMO) and the US climate and weather agency Noaa.
Dr. Lee says that in addition to measures like rest and fluids and shade for outdoor workers, a key strategy to resist heat stress is to be fit.
“By staying fit aerobically, you’re also increasing your tolerance for heat, and there are many other benefits as well.”
And he sees the challenge for doctors, sweating inside his PPE while dealing with Covid-19, as “almost like a dress rehearsal” for future temperature rises.
“This climate change will be a bigger monster and we really need a coordinated effort between nations to prepare for what is to come.
“If not,” he says, “there will be a price to pay.”
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