Heat Stress and the World Cup

world cup soccer






With the world cup well underway and the controversy of the selection of Qatar as host for 2022, it is topical to look at the impact of heat stress on the event. A few quick calculations using the Basic Thermal Risk App (BTRA) for three games already played give some indication of the impact.

Match Location (Brazil) Air Temp & Relative Humidity (average) BTRA Heat Stress Risk Advice
Australia vs Chile Ciuaba 24⁰C @ 73% RH Low to Moderate
England vs Italy Manaus 27⁰C @ 74% RH Increased risk for heat illness
Japan vs Ivory Coast Recife 24⁰C @ 93% RH Low to Moderate

At these levels it looks quite manageable. However what happens if we select Doha in Qatar as a location at the same time of the year and playing time?

Based on average meteorological data from the Metcheck.com website and using the same criteria as for the table above in the BTRA, we would be looking at approximately:

Main Game of the day Doha (Qatar) 42⁰C @ 35% RH The onset of heat induced illness is very likely and corrective action needs to be taken ASAP

Probably not unexpected and remember this is only a simple estimation tool. If we then model this using the ISO 7933 Predicted Heat Strain approach we can see from below that most players core temperatures (that is the internal body temperature) would be reaching 38⁰C at around approximately the 29 minute mark (see below). This does indicate that the initial estimate of the BTRA is correct as the risk of a heat stress illness increases rapidly once the core temperature exceeds 38⁰C.


There are a number of actions that should be triggered at this point not the least to include re-assessment of current controls and the introduction of additional potential controls. Ultimately it may also be useful to consider some physiological monitoring where appropriate.

The above is an example of an assessment approach that can be used when anticipating potential heat stress issues or even if unsure and just to check.

Bringing this closer to home, how often do we see junior sporting events held in the hottest part of the day without appropriate preparation? Do the organisers take the heat of the day into account? Do we build in additional time to get off the sporting field to rest in a cooler or shaded environment for a better recovery? Do we ensure there are adequate fluids available and the opportunity to actually drink them?

It does seem obvious and straight forward and not difficult to manage but we continue to have issues in the workplace and on the sporting field and at all levels. If you think this only applies in junior sporting events, just cast your minds back to the Australian Open Tennis in Melbourne in 2014. Could that have been managed better?


Sporting events can present a serious risk of heat illnesses and they should be assessed in the same way we do for our workplaces. Both junior and elite athletes can be harmed if heat stress is not anticipated and managed appropriately.

No matter what the scenario we must put the health of the individual first and foremost.


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  • Rocky Petrocchi says:

    Has anyone tried using large fans placed along the sidelines with water jets behind them and all of them pointed toward the middle of the field? The relatively low humidity in Qatar should promote rapid evaporation of the misted water resulting in evaporative cooling of the air being blown out of the fans. Since cooler air is denser than warmer air, this should result in a cooler blanket of air being laid down on the field. I’ve seen this done in tire shops indoors and outdoors on small scales but have never seen it done on a soccer field scale. I wonder if there is some kind of computer model available that could tell you how many and how big the fans would have to be to make this feasible. Just a thought stepping out of the box…..

    • Ross Di Corleto says:

      The physics is good, based around the evaporative cooling effect but scale might be an issue. I have also seen this done at outdoor restaurants but the logistics on the scale of the world cup would be very complicated and you would need this duplicated across many stadiums not just one. If you don’t get it right and the water is not fully evaporated could it end up making the issue worse by creating a micro environment and increasing the relative humidity?
      Also to throw a curve ball in there, given the climate could it potentially introduce an issue with waterborne diseases (i.e. legionella) if the water storage conditions are not correctly maintained.

  • Leo Vortouni says:

    They have so much money over there that they could easily build an enclosed stadium and have it airconditioned!

    • Ross Di Corleto says:

      Given the number of stadiums they would have to build I don’t know if the economics (and time) is there. Maybe a simpler solution would be to just shift it to a cooler time of the year.

  • K.N.Krishna Prasad says:

    Knowing this with certainity, how far is it wise to have the tournment in Quatar. The country is now thinking in terms of prestige and fianacial gains. Soo after the games, every one will start cusring the Organizers for their “wisdom”.

    K.N.Krishna Prasad
    HSE Consultant and Trainer

  • The devils in the detail when it comes to effective heat acclimation. Professional athletes tolerate core temps >38C for extended periods when they are appropriately prepared. core temps increase rapidly in footballers (all codes) in cold conditions too, due to large metabolic demand, & not uncommon to see > core temp in winter compared to summer, as work rates are higher; >39.5-40C. Heat stress prediction models are far less relevant in sport comparred to industry

    • Ross Di Corleto says:

      Thanks Simon, It is always an interesting cross over when we look at approaches used in industry for sport and vice-versa. You are indeed correct in that we are dealing with very fit athletes here and not the average worker so the same rules may not always apply. The use of 38.0C as a limit mark is a conservative approach recommended by the WHO and I know that core temps in some underground miners have been recorded around the 39.0C mark on a regular basis with out significant negative impact. I guess it comes back to a risk based approach. If we look at one individual there is one level of risk but when you have 32 squads with 23 members and then you add 75 referees, that’s a lot of exposure.

  • Vinod Gopaldasani says:

    The risk of heat stress would indeed be very real in Qatar. While the logistics behind evaporative cooling effect using mist fans across the large surface area such as a football stadium seems difficult across seven or eight different stadiums with other risks e.g. Legionella being introduced, it would be prudent to insist that all qualifying teams for the Qatar world cup come at least a month or two in advance to get acclimatised to that environment. This is especially important for countries that are never exposed to such high environmental temperatures. Staying hydrated too would be an issue as players would lose far too much fluids through sweat than they would have time to replace. Perhaps having drink breaks (like in cricket) should be introduced. Shifting play to late evenings and nights would help only slightly as temperatures would still be in the 30s which would still be considered hot for many countries. Overall it would be interesting to see how this plays out in 2022.

    • Ross Di Corleto says:

      Some good points there Vinod, I think most teams would be looking at the acclimatisation aspect closely and send teams earlier. Some have even done it for this World Cup. An interesting snippet i picked up is that because of the relatively high ambient temperatures in Brazil, particularly at the northern venues, “cooling breaks” for the players have been introduced. Breaks can take place after the 30th minute of the first and second half of games at the referee’s discretion if the Wet Bulb Globe Temperature exceeds 32 °C.

  • Hi Ross, a couple of comments regarding your latest blog. At the elite level, endurance athletes are accustomed to high metabolic heat production and body heat storage. When competing in warm and hot conditions, body heat storage is generally very rapid. Examples include personal observations of rugby league athletes > 39.5C in the 1st half, AFL athletes >39.5C in the 1st quarter and field hockey athletes >40C in the 1st half to name just three. In each of the aforementioned examples, athletes were asymptomatic for heat illness and completed their respective games without incident. In this regard, standards applied to occupational settings are less relevant for elite athletes. Core body temperatures greater than 38C may simply be considered ‘operating temperature’ for elite athletes in warm to hot conditions. Control measures to maximise athlete performance and mitigate the risk of heat related illness generally focus on cooling measures. For an overview of elite athletes competing in the heat and cooling measures, see Chapter 9 of the sport science bible http://bit.ly/1rmLxL0.

    There are also many examples of athletes commencing competition with with core body temperatures >38C. Monitoring of drivers at todays V8 Supercar Championship event at Hidden Valley, Darwin provided several examples. For additional information regarding thermal responses of motorsport athletes see http://1.usa.gov/1lgZjhD and http://1.usa.gov/V1QOgS.

    While occupational and sporting settings can face similar challenges in the heat, elite endurance athletes spend a large proportion of time preparing (training) for a relatively brief performance. Conversely, workers generally spend a modest amount of time preparing (training) their bodies for a relatively long performance (work hours per week).

    Recreational athletes should also be considered distinct to elite athletes but that’s a discussion I’ll save for another time. Cheers, Matt.

    • Ross Di Corleto says:

      Thanks Matt for the info and great links. From your comments and Simon’s it is very obvious that there is a significant difference in dealing with the occupational and sporting scenarios (particularly at the elite level). I guess it emphasises the point that there is more to the management of heat stress than meets the eye in the sporting arena. Whilst I can see that the tolerance levels of the elite athletes is higher than most individuals (and in the example I presented) I would guess that there would be some inter-individual variation in those levels. Out of those 800 odd participants there is still likely to be some increased risk, though not as high as I had originally thought.

      • Hi Ross, further to the discussion, I would expect many of the current standard industry heat policies within industry would change if contemporary acclimation prep and monitoring methods were rigorously applied. In sport, amongst other things, we are also finding that permissive dehydration during heat acclimation training accelerates key physiological acclimation responses and adaptations (partly due to include upregulation of fluid retaining hormones). Physical prep is by far the best way to prepare for working and competing in the heat.

  • BJ Duerson says:

    42 C is an extreme temperature to do anything in. In Arizona and California, when those temperatures were reached during the day, work shifts were shifted so work was performed at night. Not only are the athletes at serious risk, at those temperatures even the fans would be at risk. Just sitting there in the sun I would expect several spectators to suffer heat stress. Acclimation only goes so far before extreme circumstances prevent work to be done without PPE. I dont think FIFA nor the players would support the use of in game cooling vests. The only appropriate alternative I think would be to build an enclosed stadium with air conditioning. This is the only way both athlete and spectator could be protected. This however is something that is not very economically feasible, even for Qatar. If Brazil spent around 250 million per stadium, I think costs would be even greater due to enclosure and higher worker wages. I think the heat presents serious concern and an alternate site needs to be given serious thought. In my opinion concern Qatar is an unfit site to hold the World Cup.

    • Ross Di Corleto says:

      BJ you raise an interesting point I hadn’t considered, what about the spectators? We saw images in the media earlier this year of spectators as well as players in some distress at a major sporting event held in summer in Australia. The education would need to be spread across a number of groups not just the athletes.

  • It would be interesting to do the calculations for an Australian Rules game in Darwin in November in the “build-up” to the Wet Season.
    The shade temperature would be less than 37 C, but the humidity would be close to 100% and the air can be almost still. Plus the hot sun.
    The local story is that it takes a couple of years conditioning to be able to play a full game under those conditions.
    I could manage 10-15 minutes moderate to heavy work before having to rest for half an hour.

  • Ruby Corkill says:

    Loved it. Really interesting stuff. Keep up the good work

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