The heat does not mix well with the high blood pressure, diabetes, or kidney conditions. It wreaks havoc with antidepressants, beta blockers, vasoconstrictors, migraine and allergy meds.
And then -- there's the brain on heat. You know it but you don't know it: you can't think straight or control impulses. Deciding between a taco or a burrito can put you over the edge. Now perform a job under that condition. Overheated air traffic controllers? No thanks, I'll drive. Overheated data entry clerk? Problems add up. You start feeling the three i's: (b)itchy, irritable, implosive.
It's just too simple to prevent health risks to imagine anyone suffering from the heat. Hydrate! Wear a cooling vest to cool your core! A cooling headband to cool your brain! Stay inside, jump in the pool, reschedule your game. You're worth more than a hot gamble with the universe.