I downvoted because your statement about 'most employers..' is not true. There is NO maximum working temperature in Ontario's occupational health and safety policy. I can tell you many worksites pass 34C on a regular basis. Much of the world functions easily in 34C, as your body can still cool itself by sweating,  if we were talking above 40C I would agree, but there is no need to spend the ridiculous sums for A/C for a handful of days a year....