Once the wet bulb temperature crosses 35C sweating is not enough to cool the human body. Even healthy people die within few hours.

In some places that temp has been crossed for short time already. When people are poor and there are blackouts the situation can become catastrophic.

In Jacobabad (Pakistan) wet bulb temp recently crossed 35C. "Hotter than the human body can handle: Pakistan city broils in world’s highest temperatures" https://www.telegraph.co.uk/global-health/climate-and-people...