Enhancement of measures to prevent heatstroke in the workplace following the regulatory revision

5 June 2025 2 min read

At a glance

  • This regulation aims to ensure the protection of workers' lives and physical wellbeing in Japan's hot and humid summer environment.
  • While this regulation formally applies to indoor office workers as well, its primary objective is workers in factories, construction sites, or other such environments.
  • This regulation applies to work expected to be performed for more than one consecutive hour or more than four hours in a day under conditions where an indexed heat stress measurement (the Wet Bulb Globe Temperature (WBGT)) is 28°C or higher, or the air temperature is 31°C or higher.
  • Employers must establish a system in the workplace that enables workers to report if they experience symptoms of heatstroke themselves or notice others at risk.
  • Employers must prepare and communicate guidelines on necessary actions to be taken for workers at risk of heatstroke, including measures such as body cooling and transportation to a hospital.

In Japan, due to the highly hot and humid conditions during the summer, there has been a growing rate in recent years of occupational accidents caused by heatstroke in the workplace. As many fatal incidents from heatstroke are attributed to the neglect of early symptoms and delays in response, the Japanese government has established this regulation requiring employers to take specific measures to prevent heatstroke among their workers.

The scope of this regulation is limited to environments where the WBGT, which is a combined measure of temperature and humidity, is 28°C or higher, or the air temperature is 31°C or higher. It is generally understood that the regulation does not apply to workplaces such as offices where air conditioning is fully installed. On the other hand, Employers who operate workplaces that are vulnerable to heat and humidity-such as factories or construction sites-must establish and implement these measures.

Specific measures

It is essential for employers to constantly monitor the temperature and WBGT index of the workplace. Employer must clearly designate and communicate to workers to whom they should report if they feel at risk of heatstroke themselves or notice other workers who may be at risk of heatstroke. Employers also must establish guidelines on necessary actions to be taken for workers at risk of heatstroke and communicate them to workers in the workplace. The specific measures that employers must take and include in their guidelines are not prescribed by law. For example, the guidelines may include procedures such as allowing a worker at risk of heatstroke to rest in a designated room, providing body cooling and hydration, and calling an ambulance to transport the worker to a hospital where they present certain symptoms suggesting they require urgent medical treatment.

Employers with workplaces affected by temperature and humidity must implement specific heatstroke prevention measures for the workers, communicate those measures to them, and ensure their thorough compliance.

Penalties and damages

Employers who violate this regulation are subject to a penalty of imprisonment for up to six months or a fine of up to JPY500,000. That said, these penalties are imposed only in cases of a malicious violation. If a worker dies or suffers a lasting injury due to heatstroke during work, the company may face the risk of a claim for damages.