What we know about heat and health
There is a fair bit known about heat, humidity, the wet bulb temperature and that fit young men and women can easily die of heat stress. Dogs pant and elephants flap their ears in extreme heat; humans sweat. When sweat evaporates we lose a little heat, lowering our core temperature. We also have long known that humidity greatly increases the danger of heat, as in humid environments our sweat does not easily evaporate. Thus, sweating when it's humid is not as effective.
If the wet bulb temperature reaches 35 degrees C. then even a fit person will die, probably in just a few hours. Such wet bulb temperatures are still extremely rare, but by treating our atmosphere as an open sewer, as recommended by a legion of politicians, we are on track to make some parts of the world completely uninhabitable if we go outside. If you are not fit, you will probably die even sooner, and at wet bulb temperatures below 35 deg C.
We also know that people with pre-existing illnesses are more vulnerable to acute heat effects, manifesting within minutes, hours or perhaps days. We know that in the 2009 heatwave in Victoria, where 173 people died in bushfires, even more died in Melbourne from simple heat exposure. (See the Victorian Department of Health report.)
Acute (rapid onset) symptoms can be reduced and hopefully prevented by drinking, cooling and stopping exertion. Sports people can drink, apply ice, and maybe even have the roof lowered so there is shade - but they can't stop their exercise without losing.
Heat can, in some locations, especially cities, elevate exposure to troposphericic (low-level) ozone (mainly from traffic), which harms lung function.
We have virtually no idea of the long term effects of excess heat
In contrast to the knowledge on acute exposure to extreme heat, we know next to nothing about the long term effects, other than some data on renal impairment and urinary tract stones due to prolonged dehydration, mainly affecting agricultural workers with inadequate water access. We also know a little about sudden, often mysterious deaths in exploited construction workers, particularly in the Middle East. But we know next to nothing about the life expectancy and other health indicators of those workers who do survive. (And we are not likely to - their employers will not welcome such studies.)
The starting position of those running the Australian Open appears to be that if a player or spectator survives symptomatic heat stress then their future health will be completely unaffected. But this may be wishful thinking. We don't even know that if someone who experiences extreme heat exposure, but is completely without symptoms, will be ok in the long run.
In fact, the converse is more plausible. It is, for example, highly likely that those who are vulnerable to heat (such as the elderly and those with pre-existing conditions, e.g. heart failure, dementia or many other severe chronic diseases) who do not die will have a step-like fall in their function, at least temporarily. Will they recover that full lost step? Over what period? How many will have a mishap, such as a fall, before they fully recover, in the weeks or months after the heat event? In the elderly, falls can be very serious, and often presage death.
It is also well-known that many multiple sclerosis (MS) patients experience a decline in function during heat - heat slows nerve conduction. Could excessive heat tip some people, previously unaffected, into neurological conditions, including migraine? (French tennis player Gael Monfils reported extreme dizziness at the Australian Open). We don't know. We do know that people at higher latitudes have more MS. The dominant explanation is that such people are exposed to more ultraviolet light, but could a factor be that, in part, over long periods of time, such people have sought to live in cooler conditions? Or perhaps that those with MS in very hot areas aren't able to have the same reproductive success?
Extreme heat also has harmful effects on unborn children
Human bodies can be thought of as complex mixtures of chemicals and electrical signals. We have evolved to live in an "envelope" of temperature and humidity, an envelope many people are now exceeding. How do we know that proteins (or any other bodily component) repeatedly exposed to high temperatures will completely recover? Is that plausible?
"The healthy player effect"
Sure, we see champions like Roger Federer appearing to function well, despite the heat. But could there be a "healthy player effect"? That is, might we not learn a lot more about the adverse effects of extreme heat upon sportspeople by studying people who abandoned sport, or perhaps switched to a winter sport, due to their discomfort with heat? My former mentor, Tony McMichael, coined the term "healthy worker effect", recognising that studying the health of long-term factory workers told only a small part of the story.
The NH&MRC's failure to recognise the risk of chronic heat effects
Between 2012 and 2016 I repeatedly proposed research projects to investigate aspects of these questions, but with no success. The National Heath and Medical Research Council has declined to fund at least six large grant applications of relevance. (I was involved with five of them, one of which I led).
It is unconscionable to treat athletes and spectators in hot conditions as guinea pigs. Many emergency workers such as firefighters and military personnel have to endure such heat. We urgently need to better understand the long term risks that those workers face, and, if we find them, then try to work out ways they can be protected. However, until we know, spectators and athletes will be better protected by a change in the date of the Australian Open, cycle races, and in the near future, cricket.
Decades of denial and neglect about climate change, such as by former Australian Prime Minister Tony Abbott (a keen cyclist), have created this crisis. Let us not compound that negligence. Ignorance is no defence. We have a duty of care to investigate chronic health effects of heat. I have a duty to add my voice about these many concerns.
PS A correspondent has suggested that the stadium could be retrofitted to have water flowing through tubes under the court to extract heat from the slab, and possibly the stands, circulating it for other uses. If the roof were closed and the air conditioning turned on, the mass cooling would possibly use less energy that individuals if they were at home turning on their air conditioners. A greater use of solar panels would lower the greenhouse gas footprint of the stadium, offset the carbon emissions the complex uses from the grid (as Victoria still uses mainly coal-fired power), and create good will.
However, some observers may claim that a cooled stadium would give an unfair advantage to players (especially higher ranked seeds) who are more likely to be chosen to play on that court.
About the author
Adjunct Professor Colin Butler graduated in medicine in 1987, and has four post-graduate degrees or diplomas in public health, including a PhD in epidemiology and population health from the Australian National University (awarded in 2002). He also has over 10 years of clinical medical experience, mainly with elderly, disadvantaged patients, in the Australian state of Tasmania. He is one of only two living Australian contributors to the health chapter of the most recent IPCC report.
In 2014 he became the first Australian IPCC contributor to be arrested for civil disobedience about climate change, attempting to draw more attention to this crisis. He is sole editor of the book Climate Change and Global Health (CABI, 2014). In 2010 he was awarded a Future Fellowship by the Australian Research Council, allowing 4 years of independent research on topics related to global environmental change and health. He has experienced hate mail and an official complaint to his former university, due to his activism over climate change. His first article on climate change and health was published in the Medical Journal of Australia in 1991.