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Guideline

Administrative Information

Notification
Preventive Measures for Heat-Related Illness (1996)
* No. 329, May 21, 1996
* Addressed to Director-Generals of the Prefectural Labor Standard Bureaus from Director-General of the Labor Standards Bureau, Ministry of Labor
In Japanese

In record-making heat waves during the summer of 1994 and 1995, fatal accidents caused by industrial activities occurred in numbers from July to August, predominantly in outdoor work on construction sites. These are attributable to heat-related illness. Under these circumstances, the need for having an emergency plan in place to prevent heat-related illness has arisen.

The prime cause of the occurrence of heat-related illness is the lack of awareness of the degree of ignorance concerning the dangers of working in a hot environment. In investigating the actual circumstances, many cases are caused by: insufficient time for breaks, insufficient amounts of fluid and salt replacement, and a lack of information on the workers' state of health. That means that the occurrence of heat-related illness is preventable through providing both industrial management and workers with the essential knowledge to prevent heat-related illness by taking appropriate measures.

Consequently, for the purpose of preventing heat-related illness, thorough and proper guidance to the related industry sectors and companies on workers' activities in a hot environment such as outdoor work during the summer season, etc., is required. A brochure may be of use for this purpose, which is among the items listed below and will be sent separately to all concerned.

Further, since more than half of the fatal accidents attributable to heat-related illness are within the construction industry, please note that a particular request has been made by the concerned office to the related bodies as attached (editor's note: omitted).


Account
1. Work Environment Management

(1) To install shielding, etc., that is able to block the heat between a heating source and a working place with a high environmental temperature (hereinafter simply called 'working place'). For an outdoor activity, to provide a simple, prefabricated roof, etc., which blocks the direct rays of the sun as far as possible.
(2) To equip the working place with facilities for ensuring an adequately ventilated and air-conditioned environment. During working hours, to occasionally sprinkle the place with water.
(3) To prepare goods or facilities that can adequately cool down workers' bodies, for example, water, cooled hand towels in the working place, or facilities for a cold water bath or a shower somewhere nearby.
(4) To secure a cool rest station such as an air-conditioned room or a shade area somewhere adjacent to the working place. The rest station should have sufficient room to lie down.
(5) To provide some means by which workers can easily replace fluid and salt, for example, by providing sports beverages in the working place.
(6) To install a thermometer and a in the working place and pay sufficient attention to changes in the temperature and humidity during working hours.

2. Work Management

(1) To provide a recess or break time during working hours according to the temperature conditions, type of work, workers' state of health, etc. Especially, energy-consuming work including digging involving manual or continuous work should be reduced as much as possible.
(2) To avoid clothing which tends to absorb or keep in heat, and choose material that absorbs moisture well and is highly porous.
(3) To ensure that workers wear porous headgear under the direct rays of the sun.

3. Health Care Management

(1) Based on the results of the most recent medical examination, to give proper health care and assign an appropriate work post.
(2) To give workers education in daily health care regarding proper hours of sleep and proper nutrition. If required, to counsel them about health problems.
(3) To confirm each worker's state of health before starting work. I addition, to check in advance the condition of the work place, and confirm workers' health conditions through frequent visits to the place and speaking to them. Where there is more than one worker, to encourage them to check on each other's state of health.
(4) To give workers appropriate guidance on fluid and salt replacement, etc.
(5) It is desirable to install a clinical thermometer in the rest station and encourage workers to often check their own body temperature.

4. Industrial Health Education

In advance of carrying out work in a hot environment, industrial health education should be given on the following items to work management personnel and workers.

1) Symptoms of heat-related illness
2) Measures for the prevention of heat-related illness
3) Measures to take in emergencies
4) Case examples of heat-related illness

5. Emergency measures

(1) To coordinate an emergency network and make it known to all related personnel in advance. To identify the location of hospitals and clinics and related contact information.
(2) When there is any sign of heat-related illness, as an emergency measure, to move the victim to a cool place, cool his or her body down, and replace fluid and salt. If necessary, to give the victim medical attention.


(Reference 1)


Heat-Related Illness

Heat-related illness is a general term which describes the state having difficulty or inability to perform working due to high environmental temperature and humidity, which has resulted from the affected thermoregulation or blood circulation functions, or a significant loss in the metabolic balance of fluid/salt. Pathophysiologically, heat-related illness is classified into heat stroke, heat cramps, heat syncope and heat prostration. As for heat stroke, the term here indicates that which occurs in the direct rays of the sun.

1) Heat Stroke

Of several kinds of heat-related illness, heat stroke is highly life-threatening and immediate medical intervention is essential. In outdoor activities in the summer season or indoor activities in a high ambient temperature, when the victim experiences impaired consciousness with an extremely high body temperature, and as long as no other particular cause is indicated, the diagnosis will be heat stroke.

It is attributable to the disorders of thermoregulatory abilities and the central nerve system along with a rise in body or cerebral temperature. An abrupt loss of consciousness occurs in many cases and symptoms such as dizziness, nausea, headache, tinnitus and irritability may precede, sometimes including vomiting and diarrhea. The sweating mechanism fails, the skin gets hot and dry, and the body temperature usually exceeds 41°C, often reaching 42°C and over.

<Emergency Measures>
Strip the victim nearly naked, loosen clothing, sprinkle him or her with cool water, and at the same time expose him or her to the wind with an electric fan; massage the victim using ice cubes; and wipe the whole body with alcohol-soaked cotton. In order to lower the body temperature, undertake whatever active measures are available.

2) Heat Cramps

Heat cramps result from insufficient replacement against depleted body salts caused by profuse sweating. Extremities and abdominal muscles that are strenuously used while working have a fit of intense, painful spasms. Sometimes it occurs not only while working, but also when taking a bath after work or while sleeping.

In heat cramps, the body temperature hardly rises, and in addition, there is no change in blood pressure.

<Emergency Measures>
Give the victim a saline solution of 0.1% concentration and let him or her rest in a cool place.

3) Heat Syncope

In a hot environment, the dermovascular bloodstream increases in order to actively radiate heat from the body. At this time, since there are decreases in vascular flow to internal organs, returning flow back to the heart for cardiac output, then hypotension occurs and there is an increase in the heart rate to compensate. Heat syncope has symptoms centered on circulatory failure, which occurs when the heart rate has exceeded a certain limit due to a long period of exposure to the heat.

In some cases, symptoms of heat cramps include general malaise, lethargy, clouding of consciousness due to dizziness, and even insensibility. The pulse is tachycardial and weakened, and there is hypotension. There is hardly any rise in body temperature.

<Emergency Measures>
Rest the victim in a cool place and give him or her water.

4) Heat Prostration

Profuse sweating causes intravascular coagulation, resulting in an increase in the work of the heart or abnormal blood distribution. Then early symptoms, including an extremely dry mouth or a decrease in urination, will start, followed by dizziness, paresthesia in the extremities, difficulty in walking, or even fainting. Sometimes there are symptoms of tachycardiac heartbeat or a rise in body temperature, although due to such profuse sweating the skin is cold and wet. Usually, blood pressure is normal.

< Emergency Measures>
Rest the victim in a cool place and give him or her water.


(Reference 2)


Heat-Related Illness Contributed to Fatal Accidents caused by Industrial Activities

In 1994 and 1995, successive severe heat waves resulted in the many fatal accidents caused by industrial activities.

Changes in the Total Number of Deaths
Year 1989 1990 1991 1992 1993 1994 1995
Number of deaths 1 11 7 4 1 20 24

The fatal accidents due to heat-related illness in 1994 and 1995 are summarized below.

1) Fatal Accidents by Month

The fatal accidents were clustered in July and August, particularly in the first ten days of August.

2) Fatal Accidents by Industry

In both years, the construction industry accounted for the main portion of the accidents. In addition, as for industries other than the construction sector, many cases were in construction-related work such as a security guards, guides for vehicles, etc., on construction sites.

When looking at the location of cases outdoors or indoors, the number of cases getting heat-related illness due to outdoor activities, for example, while working in outdoor construction sites, weeding around factories, etc., predominate.

3) Fatal Accidents by Time of Day

Many cases occurred in the period between 11:00 and 17:00, although, in the 13:00-14:00 period, after lunch time, the number of occurrences becomes extremely low so that only 1 case was reported in 1995. This is thought to indicate that heat-related illness tends to occur during periods of high ambient temperatures, while rest and fluid replacement are significant as preventive measures for heat-related illness.

4) Fatal Accidents by Age

Through the method classifying the deceased aged from 20 years old up to 70 years old and over into 10-year age groups, there is a clear tendency for the number of accidents to increase with age, with the peak in the 50-60 group. Particularly in 1995, the accidents were clustered in the 50-60 group as shown from the fact that 15 cases (63%) out of a total of 24 belonged to this group.

1) Fatal Accidents by Month



2) Fatal Accidents by Industry

1994


1995




3) Fatal Accidents by Time Period



4) Fatal Accidents by Age


5) Case Examples

Case Summary Ambient Temperature at Occurrence (Ambient Humidity at Occurrence) Cause Month of the Occurrence
On the construction site of a viaduct on the Shinkansen (bullet train railway), on the way to lunch, the victim was walking unsteadily and carried to the hospital, but died there. 34.3°C
(40%)
 Outdoor working in a place that was scorchingly hot from reflected heat
Insufficient salt replacement
A lack of information on the workers state of health
A proper rest station was not provided		 July
While redoing temporary scaffolding, the victim felt unwell and was carried to the hospital but died there. 29°C
(70%)
 Outdoor work
Insufficient time for breaks
A lack of information on the workers state of health
 July
On the construction site of an 11-storey residential building, while leveling in concrete casting work, the victim felt unwell and was carried to the hospital but died there. 33.2°C Outdoor working in a hot place from reflected heat and without shade
A lack of information on the workers state of health
Insufficient time for breaks
Clothing of low breathability
 July
During paving work, while carrying stones, the victim collapsed. 32.5°C
(57%)
 Outdoor working
Insufficient replacement of fluid and salt
Insufficient time for breaks
A lack of information on the workers state of health
 July
During outdoor work under the roof, while conveying iron bars on a forklift, the victim felt unwell and collapsed after got out of the vehicle to adjust the setting down area, etc. 36°C
(65%)
 Outdoor work in a windless placeInsufficient time for breaks August
After digging a flower bed using a small backhoe, while leveling the surface with a scoop, the victim collapsed. 36°C
(45%)
 Outdoor working in a hot place with reflected heat
Insufficient replacement of fluid and salt
A lack of information on the workers state of health
Insufficient knowledge about treatment, etc., in an emergency
 August
While casting concrete, the victim felt unwell and collapsed in the parking area remote from the site. 38.2°C
(52%)
 Outdoor workInsufficient time for breaks August
While breaking concrete foundations, the victim collapsed. 33.3°C
(60%)
 Hard work in an unshaded outdoor place August
While moving a fence for a substation within the factory premises, the victim collapsed due to a heat wave. 32°C
(52%)
 Outdoor work
A lack of information on the workers state of health
Insufficient time for breaks
Insufficient knowledge about treatment, etc., in an emergency
 August
In slab reinforced concrete work, while doing bar arrangement work on the construction site of an apartment house under the hot sun, the victim felt unwell and went home, showed no improvement and was carried to the hospital, but died there. 28.6°C
(74%)
 Hard work in a hot place with reflected heat and a lack of wind
Insufficient time for breaks
Insufficient replacement of fluids and salt
Insufficient knowledge about treatment, etc., in an emergency
 August
While working as a construction worker on the construction site of a new sewage system, the victim felt unwell and was carried to the hospital but died there. 36.4°C Outdoor work in an unshaded placeA lack of information on the workers state of healthInsufficient knowledge about treatment, etc., in emergency August
While cleaning up after concrete foundation work, the victim lost consciousness and died. 35.7°C
(36%)
 Outdoor work in an unshaded placeA lack of information on the workers state of healthInsufficient time for breakInsufficient replacement of fluid and saltInsufficient knowledge about treatment, etc., in emergency August
While moving water pipes, the victim collapsed on the site. 33°C Outdoor work in an unshaded placeInsufficient replacement of fluids and salt August
While working as an assistant worker in framing a molding form for the foundation of a border fence, the victim collapsed. 35.1°C
(45%)
 Outdoor work in a scorchingly heat reflected placeA lack of information on the workers state of health August
On a construction site, during work as a labor assistant for back filling work with a mechanical shovel, the victim collapsed while accumulating earth and sand using a scoop. 36.5°C
(62%)
 Outdoor work in an unshaded placeA lack of information on the workers state of healthInsufficient replacement of fluids and salt August
While working as a guide for vehicles, security guard, etc., around the gate of a construction site, the victim collapsed. 30.6°C
(64%)
 Outdoor work
A lack of information on the workers state of health
 August
On the way home after metal product manufacturing work in the factory, the victim collapsed in the parking lot of the factory premises. 36°C
(55%)
 Indoor working in a windless placeEffective air conditioning equipment not installed July

Note: 1) Ambient Temperature at the Occurrence and Ambient Humidity at the Occurrence show figures for the area around the scene of the accidents on the date of the occurrence as observed by the respective meteorological observatories.
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