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28. Prevention of anoxia, etc.

Disasters caused by anoxia, etc. occur in many industries such as civil engineering and construction fields, chemical plants and the food manufacturing industry. Such disasters could be very serious, possibly involving death, and in many cases rescuers themselves have also fallen victim. Employers are therefore requested to take the following measures for preventing such disasters. (The Ordinance on Prevention of Anoxia, etc.)

1. Classification (Article 2 of the Ordinance)

a. Anoxia
This is a condition that occurs when a person inhales air containing less than 18% of oxygen.

b. Hydrogen sulfide poisoning
This is a condition that occurs when a person inhales air containing more than 10/1,000,000 of hydrogen sulfide.

2. Hazardous work in oxygen-deficient air (Article 2 of the Ordinance, and Annexed Table 6 of the Enforcement Ordinance of Industrial Safety and Health Law)

a. Class-1 hazardous workplaces of anoxia
(a) Inside a well, shaft or tunnel in contact with or communicating with a gravel layer having a water impermeable layer on it, a stratum containing a ferrous salt or manganous salt, a stratum containing methane, ethane or butane, a stratum from which carbonated water springs, or a sapropel layer, etc.
(b) Inside a well or the like not used for a long time
(c) Inside a culvert, manhole or pit
(d) Inside a steel boiler, tank, reactor column, hold or the like closed for a long time
(e) Inside a storage facility such as a tank, hold or hopper containing a substance capable of absorbing oxygen in air such as coal, scrapped iron, wood chips or fish oil
(f) Inside a basement, warehouse, tank, hold or the like coated with a paint and closed before the paint is dried
(g) Inside a silo, warehouse or the like used for storing cereals or the like, ripening fruits or vegetables, germinating seeds, culturing mushrooms or the like
(h) Inside a tank or brewing vessel containing or having contained a substance to be fermented such as soy sauce or sake
(i) Inside a refrigerator, freezer or freezing container containing dry ice
(j) Inside a boiler, tank, reactor, hold or the like containing or having contained an inactive gas such as helium, argon, nitrogen or flon

b. Class-2 hazardous workplaces of anoxia
(a) Inside a heat exchanger, culvert, manhole, pit or the like containing or having contained seawater
(b) Inside a tank, hold, vessel, manhole or the like containing or having contained a substance likely to be putrefied and decomposed such as night soil, sapropel, sea wage, pulp solution or the like

3. General preventive measures

a. Measurement of working environment (Article 3 of the Ordinance)

b. Ventilation (Article 5 of the Ordinance) and use of atmosphere supplying respirators, etc. (Article 5 of the Ordinance)

c. Use of safety belt or the like for prevention of falling (Article 6 of the Ordinance)

d. Check on the number of workers when entering or leaving (Article 8 of the Ordinance)

e. Prohibition of entry of persons other than the workers concerned (Article 9 of the Ordinance)

f. Appointment of operation chief (class-1 or class-2) (Article 11 of the Ordinance)

g. Implementation of special education for workers (Article 12 of the Ordinance)
(a) Causes of occurrences
(b) Symptoms
(c) How to use the atmosphere supplying respirators, etc.
(d) Emergency evacuation at occurrence of accident and methods of first aid and resuscitation

h. Posting of watch-men (Article 13 of the Ordinance)

i. Provision of refuge devices (atmosphere supplying respirators, ladder, rope, etc.) (Article 15 of the Ordinance)

4. Measures for special work or the like in a poorly ventilated place

a. Boring: Measurement of methane and carbonic acid gas (Article 18 of the Ordinance)

b. Carbon dioxide extinguisher: Adequate operation of handle, etc. (Article 19 of the Ordinance)

c. Refrigerating facility: Structure for allowing the door to be opened from inside (Article 20 of the Ordinance)

d. Welding work using carbonic acid gas or helium: Ventilation and use of atmosphere supplying respirators (Article 21 of the Ordinance)

e. Measures for preventing the leakage of inert gas: Closing of valve or cock, locking, etc. (Article 22 of the Ordinance).

f. Gas piping work: Stop of gas such as methane, ethane, propane or butane, and ventilation (Article 23-2 of the Ordinance)

g. Compressed air method: Check for leakage of air, and measurement of oxygen concentration (Article 24 of the Ordinance)

h. Basement: Prevention of inflow of oxygen-deficient air (Article 25 of the Ordinance)

i. Work for modifying human excreta treatment equipment, etc.: Decision of adequate working method, giving knowledge on hydrogen sulfide poisoning, posting of watchman, measurement of hydrogen sulfide concentration (Article 25-2 of the Ordinance)

The next article in the series will be on the prevention of hazards due to dust.