Earlier quoted context omitted.
> Extreme heat (including heat waves that exceed this threshold) happen semi-regularly The threshold is wet bulb 35 for 7 hours. That is when fit young humans can't survive. Older people die well before that of course. And no, it doesn't happen regularly. I wasn't aware it had happened at all, although others here say it has. But it has come close. From https://www.telegraph.co.uk/global-health/climate-and-people...…
What city doesn't have running water?
It means some people simply have no means to escape such heat and will likely die.
In the US, they sometimes open cooling centers during heat waves so homeless people and poor people have a place to go. I never went to such but they did that in Fresno and bus rides were free if you said you were going to a cooling center.