As swaths of southern Europe continue to swelter under a deadly heat wave, for many outdoor workers, it's turning into a brutal endurance test.
In some cities, workers are walking off jobs — or threatening to — if more is not done to protect them and make working conditions more bearable.
In Rome, where temperatures hit a record high of 107.2 degrees Fahrenheit (41.8 Celsius) Tuesday, garbage collectors have threatened to walk off their jobs if they are forced to work during the hottest part of the day.
Public transportation workers in Rome and Naples are demanding mandatory air conditioned vehicles, as not all city buses have functioning air conditioning.
On Thursday, Italy's health ministry held emergency meetings to try to develop new protocols for public and private sector entities that employ people outside during the daytime hours to protect workers from the extreme heat.
"We are carefully following the evolution of climatic conditions in Italy and the related impacts on working and production environments: health and safety in the workplace are priorities," health minister Marina Calderone said Thursday.
In Greece, which is grappling with intense heat and wildfires, workers at the Acropolis in Athens, one of the country's top tourist attractions, are walking off their jobs in protest at working conditions.
A trade union representing staff working at archaeological sites, including the Acropolis, announced a four-hour strike every day from Thursday until Sunday.
The union said that over the past few days, its staff had worked under intense heat and "tried to respond to our tasks, despite the dangerous conditions." It added that at the Acropolis alone 20 visitors fainted due to the heat.
Last Friday and over the weekend, authorities closed the Acropolis for large parts of the day because of the heat, but it reopened fully Monday as temperatures came down slightly.
However, Greek authorities announced Thursday that visiting hours for the Acropolis and other archaeological sites will be revised again, as the country is braced for another heat wave.
Temperatures are expected to reach 111 degrees Fahrenheit (44 Celsius) over the weekend in some parts of Greece, the country's meteorological service has warned.
Heat, one of the deadliest natural hazards, is called a "silent killer" because it's not visible but can quickly turn deadly. Those who spend prolonged periods of time outside are among the most vulnerable.
This was thrown into sharp focus by the death last week of a 44-year-old road construction worker, who collapsed by the side of the road in the northern Italian city of Lodi.
The health impacts of prolonged exposure to heat "range from acute impacts such as heatstroke, to less visible, chronic disease vulnerability, especially when high temperatures meet high humidity and even more so when combined with heavy work," said Laurie Parsons, a lecturer in human geography at Royal Holloway, University of London.
"Heat under climate change is not, for most, a sudden shock, but an everyday emergency, a creeping crisis of ill health, disease, fatigue and reduced productivity," he told CNN.
Kristina Dahl, a climate scientist with the Union of Concerned Scientists, said there are simple measures that employers can take. "When it comes to protecting the health of outdoor workers during extreme heat events, there are really just three fundamental pieces — water, shade and rest," Dahl told CNN last week.
Yet some experts say many countries are far from prepared for dealing with extreme heat.
A report from the European Trade Union Institute found that no European Union country has done enough to tackle the impact of rising temperatures on the health, safety, wellbeing, and productivity of the working population.
"At present, wide swathes of workers suffer inaction on the part of employers, while authorities tend to continue to turn a blind eye regarding extreme exposure during heat waves," the report said.
Extreme heat also reveals a deep divide in the labor market, between those forced to be outside and those able to retreat to air-conditioned offices, the report added.
"Heat stress reflects and accentuates pre-existing social inequalities. Heat is a common occupational hazard for workers in low-skilled manual occupations, characterized by low income and tasks requiring physical effort," it said.
As the world continues to burn fossil fuels and pump out planet-heating pollution, experts warn that heat waves and other extreme weather events will become more common, more severe and more deadly.
A recent study by the journal Nature Medicine found that nearly 62,000 people died heat-related deaths in Europe's blistering heat wave last year. Italy was the hardest-hit with more than 18,000 deaths.
The study warned that, without effective adaptation plans in place, Europe could face more than 94,000 premature deaths each summer by 2040.
Many workers in the global supply chain will be highly vulnerable to climate change impacts like heat, Parsons said. "Getting serious about the dangers faced by workers in our global industries — from garments to construction — is a key frontier for future climate policy."
