Posted By Peter F This would depend on an assessment and would depend on the type of tasks.

Posted By Chris Packham Whereabouts in Egypt are they working? The reason I ask is related to relative humidity. When I worked in Libya (many years ago) temperatures in our oil production centre inland were several degrees higher than at the tanker terminal on the coast. However, there was also a significant difference in relative humidity, this being very high at the coast and much lower inland. As a result working in the production centre was actually much more comfortable than at the coast. This can be important. For example, sweating ceases to be an effective means of heat loss if ambient temperature exceeds 37 deg C and relative humidity is above 80%. We found fans were of considerable help in preventing heat stress in such conditions. We actually provided isotonic drinks to workers and found that this was beneficial, even if it did not eliminate the discomfort. Chris

Posted By Swis Arun, 15-20 mins ?? Every hour or once a day?

Posted By Ucan They are actually working in Cairo.

Posted By Jay Joshi There are several countries in the world where millions of people live and work without significant adverse effects because the human body is adaptable and it is not possible to provide cooling in the form of air conditioning or cooling everywhere. The most important factors are adequate hydration, clothing (not the lack of it!!!) as the type and design of clothing can influence the sweat absorption and evaporation rate and also provide a shading. Air movement facilitates evaporation of sweat and cools the body. Working under any type of shade also helps compared to working directly under the sun. Avoiding work during the hottest part of the day could be an option. Actual heat stress measurement by using WGBT should be done when there is significant physical activity requiring the use of PPE that may restrict sweating and when natural cooling is ineffective, i.e in confined or similar spaces.

Posted By SN May be missing the obvious here but why not get portable AC units ? If these guys are not doing anything physical then saying take a 20 min break really isnt going to do an awful lot if they are still exposed to the ambient temperature. After saying that 38 is still quite "do-able" for the average bloke especially if the work isnt physical. Things start getting crappy once in the 40's and very crappy in the upper 40's especially with high humidity. As a rule of thumb an average person will only going to be able to absorb 1/2 litre of water per hour regardless of the quantity you drink. This can be upped to .75 litre with the use of rehydration salts but you are always going to be in a deficit as you will sweat somewhere around 2 litres of fluid per hour if grafting. There are plenty of urine colour charts out there that relate urine colour to dehydration however the best I have seen was one poached from the US Navy that showed how many canteens of water you needed to take to get back to a happy state.