Harmony Simon, a postal worker, visiting Martine Combe in Aix-les-Bains in July.

A delivery in Wilmington, N.C., this month. Heat is linked to hundreds of workplace deaths each year, but labor groups say the true toll is unknown because heat-related illnesses are not properly tracked or reported.

The temperature on Tuesday reached 99 degrees in Central Park, where the city’s official weather station is. A thermometer there last reached that temperature in 2012.

Hansa Ahir, left, who salvages recyclable waste for a living in Ahmedabad, India, bought an insurance policy to cover her income on days when heat makes it dangerous to work.