A new report has warned that climate change is creating a "cocktail of hazards" likely to affect more than 70% of the global workforce.
The International Labour Organization (ILO) estimates that 2.4 billion of the world's 3.4 billion workers will be exposed to excessive heat during their working lives.
Workers in agriculture and other sectors involving open-air activities are particularly affected by extreme heat and UV radiation, which can cause health conditions such as skin cancer and cardiovascular diseases.
An estimated 19,000 people die every year across the globe as a result of excessive heat at work.
Outdoor workers are also exposed to air pollution, causing up to 860,000 work-related deaths annually, and pesticides, which have been linked to an estimated 300,000 deaths at work each year.
The ILO report said existing occupational safety and health (OSH) protections must be adapted to reflect a more dangerous working environment.
It highlighted a German law that ensures workers are given protective clothing against UV radiation, while praising the fact that some forms of skin cancer have been recognized as an occupational disease since 2015.
"It's clear that climate change is already creating significant additional health hazards for workers," said Manal Azzi, a member of the ILO's OSH team. "It is essential that we heed these warnings," she added.