As scorching temperatures spread, the search for ways to protect against heat stress is becoming ever more urgent

William Martínez, who as a child worked on a sugarcane plantation in rural Nicaragua, learned the hard way what many in the US and Canada are now realising: that rising temperatures are costing lives and livelihoods.

Martínez, along with fellow villagers in La Isla, found himself getting sicker as he worked long, gruelling days in the fields under the beating Nicaraguan sun two decades ago. Workers at the nearby mill, which supplies molasses to alcohol companies, began to suffer kidney failure, and would be forced out of the workforce and into expensive and time-consuming dialysis. His father and uncles, addled with the same affliction, had died when Martínez was a boy, forcing him to join the workforce.