Working long hours poses an occupational health risk that kills hundreds of thousands of people each year, the World Health Organization says.

People working 55 or more hours each week face an estimated 35% higher risk of a stroke and a 17% higher risk of dying from heart disease, compared to people following the widely accepted standard of working 35 to 40 hours in a week, the WHO says in a study that was published Monday in the journal Environment International.

"No job is worth the risk of stroke or heart disease," WHO Director-General Dr. Tedros Adhanom Ghebreyesus said, calling on governments, businesses and workers to find ways to protect workers' health.

The global study, which the WHO calls the first of its kind, found that in 2016, 488 million people were exposed to the risks of working long hours.

In all, more than 745,000 people died that year from overwork that resulted in stroke and heart disease, according to the WHO.

"Between 2000 and 2016, the number of deaths from heart disease due to working long hours increased by 42%, and from stroke by 19%," the WHO said as it announced the study, which it conducted with the International Labour Organization.

The study doesn't cover the past year, in which the COVID-19 pandemic thrust national economies into crisis and reshaped how millions of people work. But its authors note that overwork has been on the rise for years due to phenomena such as the gig economy and telework — and they say the pandemic will likely accelerate those trends.

"Teleworking has become the norm in many industries, often blurring the boundaries between home and work," Ghebreyesus said. "In addition, many businesses have been forced to scale back or shut down operations to save money, and people who are still on the payroll end up working longer hours."

Also, recessions like the one the world has seen in the past year are commonly followed by a rise in working hours, the researchers said.

The study found the highest health burdens from overwork in men and in workers who are middle-age or older. Regionally, people in Southeast Asia and the Western Pacific region had the most exposure to the risk. People in Europe had the lowest exposure.

In the US, less than 5% of the population is exposed to long work hours, according to a map the WHO published with the study. That proportion is similar to Brazil and Canada — and much lower than Mexico and in countries across most of Central and South America.

Several steps could help ease the burden on workers, the study states, including governments adopting and enforcing labor standards on working time.

The authors also say employers should be more flexible in scheduling, and to agree with their employees on a maximum number of working hours. In another step, the study suggests workers arrange to share hours so no one is working 55 or more hours in a week.

To compile the report, researchers reviewed and analyzed dozens of studies on heart disease and stroke. They then estimated workers' health risks based on data drawn from a number of sources, including more than 2,300 surveys on working hours that were conducted in 154 countries from the 1970s through 2018.