What the worksite must do under the mandatory workplace heatstroke measures (effective June 2025)

In short: The amended Industrial Safety and Health Regulations (Article 612-2), effective June 1, 2025, require employers — for work expected to continue for one hour or more, or exceed four hours a day, in a hot place at WBGT 28 or above or air temperature 31 or above — to (1) set up and communicate a system for reporting heatstroke symptoms or suspicion, and (2) create and communicate the content and procedures of measures to prevent worsening. A violation can be subject to penalties.

For labor staff at employers with high-temperature work — construction, manufacturing, transport, cleaning, security, agriculture, and the like — this article organizes, from a Shakai Hoken Roumushi's viewpoint, how to arrange the worksite, work rules, and work procedures under the 2025 mandatory heatstroke measures. For points outside a Shakai Hoken Roumushi's work — equipment design and measurement, or compensation after a serious incident — we make clear whom to assign them to.

What do the mandatory heatstroke measures effective June 2025 require of employers?

The ordinance amending the Industrial Safety and Health Regulations (Ordinance of the Ministry of Health, Labour and Welfare No. 57 of 2025) was promulgated on April 15, 2025, and took effect on June 1, 2025. The basis is Article 22 of the Industrial Safety and Health Act (measures an employer must take to prevent health impairment), and a new Article 612-2 was added to the Regulations. What is required is, broadly, the following two.

Category	What is required of the employer (Article 612-2)
Set up a reporting system (paragraph 1)	Set up in advance a system (contact point, person in charge, etc.) for a worker who has heatstroke symptoms, or who notices another worker suspected of heatstroke, to report it, and communicate it to the relevant workers
Create response procedures (paragraph 2)	Decide and communicate to the relevant workers the content and procedures of measures necessary to prevent worsening — such as removing the worker from the work, cooling the body, and having a doctor examine or treat them as needed

The key point: it does not uniformly require installing special equipment, but makes it an obligation to decide in advance, per workplace, a "mechanism for whoever notices to report immediately" and "an action procedure for when heatstroke is suspected," and to inform everyone. The details of the system and procedures are set out in a notice from the Director-General of the Labour Standards Bureau of the MHLW (Kihatsu 0520 No. 6, May 20, 2025).

How do you judge which work and workplaces are covered?

Coverage is not decided uniformly by industry but by the work's heat environment and time. The notice describes a "hot place" as follows.

Judgment factor	Benchmark for coverage
Degree of heat	A place at WBGT (wet-bulb globe temperature) 28 or above, or air temperature 31 or above (indoors or outdoors)
Continuity / accumulation of work	Work expected to continue for one hour or more, or to exceed four hours a day

Thus, not only construction sites and outdoor work but also indoor work without effective air conditioning (manufacturing, logistics warehouses, kitchens, etc.) is covered if the WBGT or temperature reaches the benchmark and the time requirement is met. Even non-routine work is covered if it is expected to meet these requirements. Which of your own operations are covered is judged by actually checking the WBGT/temperature and work time of the work location. The measurement itself is the domain of a working-environment measurement expert and specialist contractors; a Shakai Hoken Roumushi arranges the system and procedures based on the results.

In a workplace with hot-environment work, implementing periodic health checkups is also important as a basis of health management. The duty to implement them and the treatment of cost and time are summarized in how far are periodic health checkups the company's obligation.

What should the worksite prepare as system set-up, procedure creation, and communication?

The substance of the obligation is three points — "system," "procedure," and "communication." Concretely, what the worksite should prepare is as follows.

• Decide the reporting system in writing: decide to whom and to which contact (site supervisor, workplace person in charge, emergency contact) a report goes, and post/share it so all workers understand. Clarify a route by which not only the affected person but also those around them can report when they notice something wrong.
• Decide the response procedure to prevent worsening: put into a procedure the flow of removing the worker from the work → cooling the body in a cool place → having a doctor examine them or emergency transport as needed, together with who is in charge and the benchmark for judgment at each stage.
• Keep a record of the communication: communicate the procedure at morning meetings, safety and health education, and postings, and record the fact of communication (date, those covered). Because the obligation includes "deciding and communicating," the communication record is evidence of implementation.
• Confirm the contact network and the division of equipment roles: preparing water and salt, rest areas, and cooling items is part of the company's duty of care. Assign equipment responses such as air conditioning and ventilation to specialist contractors, and measurement to a working-environment measurement expert.

Where should you revise the work rules and work procedures?

The obligation mainly concerns work procedures and the safety and health system, but keeping the work rules and internal regulations consistent stabilizes operation.

• Review the safety and health provisions: position the basis for the heatstroke reporting system and response procedures in the safety and health chapter of the work rules or in the safety and health management regulations.
• Set the treatment of stopping work and rest in hot conditions: if you make a rule to stop work or grant rest in high heat, also organize the treatment of working hours and wages (how stopped time is handled).
• Build education and training into the procedure: cover prevention of and response to heatstroke as part of safety and health education, and set the timing of implementation.

These are not made once and done; they are revised in line with actual WBGT/temperature measurements and on-site operation. A Shakai Hoken Roumushi can help maintain the work rules and safety and health management regulations and with the procedures on revision (hearing opinions, notification). For sorting out workers' accident insurance and social insurance on sites where sole proprietors ("one-person masters") and multiple employers are mixed in construction, see the obligation to enroll in social insurance in construction and special enrollment in workers' accident insurance for sole proprietors; for working-hour management on sites with long on-duty hours such as security, see also napping and intermittent work in the security industry and working hours.

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Who should handle equipment responses and the response after an incident?

Heatstroke measures are not completed by a Shakai Hoken Roumushi alone. We separate the responsible parties and organize them on the premise that each is a separate, independent entity contracted separately.

What to do	Main person in charge
Maintaining the reporting system and response procedures, maintaining work rules and safety and health management regulations, designing working hours and rest	Shakai Hoken Roumushi (our office)
Working-environment measurement (WBGT / heat-index measurement), design and construction of equipment such as air conditioning and ventilation	Working-environment measurement expert / specialist contractors
Claiming workers' accident insurance and the worker casualty report if a heatstroke incident occurs	Company (supported by a Shakai Hoken Roumushi) / Labour Standards Inspection Office
Compensation and disputes over the duty of care after a serious incident	Attorney

If a heatstroke injury or illness arises during work, a workers' accident insurance claim and a worker casualty report according to the number of days of absence become necessary. The flow of the procedure is summarized in when an employee is injured at work, what does the company do? Claiming workers' accident insurance and the worker casualty report. A compensation phase where a breach of the duty of care may be alleged is the domain of an attorney.

四葉社会保険労務士事務所 can advise on maintaining the reporting system and response procedures, reviewing the work rules and safety and health management regulations, and designing working hours and rest in hot conditions. Consultation is free; fees are summarized in the fee schedule, and frequently asked questions in the FAQ.

Frequently asked questions

Q. When did the mandatory heatstroke measures start, and on what basis?
A. The ordinance amending the Industrial Safety and Health Regulations (Ordinance of the MHLW No. 57 of 2025) was promulgated on April 15, 2025, and took effect on June 1, 2025. The basis is Article 22 of the Industrial Safety and Health Act, and a new Article 612-2 was added to the Regulations. The details of the system and procedures are set out in an MHLW notice (Kihatsu 0520 No. 6, May 20, 2025).

Q. What work is covered? Is indoor work covered too?
A. Work expected to continue for one hour or more, or to exceed four hours a day, in a hot place at WBGT 28 or above or air temperature 31 or above is covered. Because it does not matter whether indoors or outdoors, indoor work without effective air conditioning — manufacturing, logistics, kitchens, etc. — is covered if it reaches the benchmark. Whether it applies is judged by actually checking the WBGT/temperature and work time of the location.

Q. Concretely, what must we prepare to have fulfilled the obligation?
A. Two things: (1) decide a system (contact, person in charge) for reporting symptoms or suspicion and communicate it to the relevant workers; and (2) decide and communicate the content and procedures of measures to prevent worsening — removing the worker from the work, cooling the body, and a doctor's examination as needed. Because the obligation extends to "deciding and communicating," it is advisable to keep a record of the communication.

Q. Are there penalties for neglecting the measures?
A. Article 612-2 is a measure based on Article 22 of the Industrial Safety and Health Act, and a violation of Article 22 can be subject, under Article 119, item 1, to imprisonment of up to six months or a fine of up to 500,000 yen. Whether a penalty applies in an individual case is a matter for the supervising authority. The basics are to first arrange the system and procedures and to carry out communication and record-keeping.

Sources

• Ordinance amending the Industrial Safety and Health Regulations (Ordinance of the Ministry of Health, Labour and Welfare No. 57 of 2025): promulgated April 15, 2025; effective June 1, 2025. Added Article 612-2 to the Regulations.
• Article 22 of the Industrial Safety and Health Act: the basis for measures an employer must take to prevent health impairment.
• Article 612-2 of the Regulations: paragraph 1 = setting up a system for a person with heatstroke symptoms or who discovers a suspicion to report, and communicating it to the relevant workers; paragraph 2 = creating the content and procedures of measures to prevent worsening — removal from work, cooling the body, a doctor's examination, etc. — and communicating them.
• Covered work ("hot place"): work expected to continue for one hour or more, or to exceed four hours a day, in a place at WBGT 28 or above or air temperature 31 or above (indoors or outdoors).
• MHLW: strengthening workplace heatstroke measures (effective June 1, 2025) and the Director-General of the Labour Standards Bureau notice (Kihatsu 0520 No. 6, May 20, 2025). Accessed October 6, 2026.
• Penalties: Article 612-2 is a measure based on Article 22 of the Industrial Safety and Health Act; a violation of that article can be subject, under Article 119, item 1, to imprisonment of up to six months or a fine of up to 500,000 yen (Industrial Safety and Health Act).
• Business of a Shakai Hoken Roumushi: Article 2 of the Certified Social Insurance and Labor Consultant Act.

This article does not decide whom to consult. 四葉社会保険労務士事務所 can advise on maintaining the reporting system and response procedures, reviewing the work rules and safety and health management regulations, and designing working hours and rest in hot conditions. Working-environment measurement (WBGT, etc.) is the business of a working-environment measurement expert, the design and construction of equipment such as air conditioning and ventilation is for specialist contractors, and compensation and disputes over the duty of care after a serious incident are the business of an attorney. These are contracted separately as separate, independent entities. Our office does not receive referral fees. The final decision on which of your operations are covered, or whether an individual workplace meets the obligation, is made by the competent Labour Standards Inspection Office and Prefectural Labour Bureau. Fees are summarized in the fee schedule and frequently asked questions in the FAQ.

This article is general information. Individual judgments — such as whether your work is covered and how far measures are needed — are made by a qualified professional after a consultation, in light of the latest primary sources (the Ministry of Health, Labour and Welfare, etc.) and individual circumstances. Written by Joji Uramatsu (Shakai Hoken Roumushi, Gyoseishoshi, Registered Real Estate Transaction Specialist).