Heat waves are particularly dangerous for homeless people, who have nowhere to cool down.
A punishing heat wave overwhelming hospitals in Europe is just the latest reminder of the deadly threat such scorching temperatures can pose to human health.
At least 150 million people across the continent were expected to experience temperatures above 35°C (95°F) on Friday, according to AFP calculations based on forecasts.
Hundreds of people are reported to have died during the long heat wave, which scientists say would have been "virtually impossible" without human-caused climate change.
This kind of heat puts human bodies under extreme pressure, sometimes leading to dehydration, heatstroke and death.
