Efforts for protecting health

• Risk assessment of specified chemical substances

  Making risk assessment obligatory at workplaces (enforced on June 1, 2016)

• Amendment of Ordinance on Prevention of Hazards Due to Specified Chemical Substances

  Addition of “welding fume” to the list of specified chemical substances subject to regulation (enforced on April 1, 2021)

  

Recently various coating agents, substances and materials have been developed, playing leading roles in industrial growth. Not only the newly developed substances but also the existing substances have tremendous effects on the human body as a result of long-term contact.
Therefore, efforts for protecting all employees engaged in work have been strengthened.

Measures against metal arc welding fume

Flow of necessary measures

• [1] Measurement of welding fume concentration (measurement of personal exposure)

  

  It is necessary to measure the welding fume concentration by means of measurement of personal exposure once by March 31, 2022

  (If changes in the welding method, welding material, base material and work area have a large effect on the welding fume concentration, however, it is necessary to measure the concentration again.)

  * Proceed to [4] when the welding fume concentration falls below 0.05mg/m³ as manganese.

• [2] Increase of air volume of ventilation system and other necessary measures

  

  • In accordance with the result of measurement of the welding fume concentration, increase the air volume of the ventilation system and take other necessary measures (excluding the following cases).
    • When the welding fume concentration falls below 0.05mg/m3 as manganese.
    • When the contents of measures are examined sufficiently in accordance with the result of measurement of the concentration at a similar welding shop in the same workplace and these measures are taken in advance at the subject shop.
    The “other necessary measures” include the following.

    • Decreasing the welding fume amount by changing the welding method, base material, welding material, etc.
    • Collecting dust using dust collection equipment
    • Blowing air using a mobile air blower
    • Installing a push-pull type ventilation system
    • Installing a local exhaust ventilation system
  • After the measures described in 1 are taken, in order to ascertain the efficacy of them, measure the welding fume concentration in the air by means of measurement of personal exposure again.
  • When measurements of fume concentration by means of measurement of personal exposure, etc. are made, record necessary items in each case (store the record for 3 years).

• [3] Measuring the welding fume concentration again

  

  After the measures are taken, it is necessary to measure the concentration again.

• [4] In accordance with the measurement result, selecting effective respiratory protective equipment and getting the workers to use it

  

  How to select effective respiratory protective equipment

  • Using the maximum value (C) of the manganese concentration obtained from the result of measurement of the welding fume concentration, calculate the “required protection factor” pursuant to the following calculating formula.
    Required protection factor    PFr = C 0.05
  • Select respiratory protective equipment having the “designated protection factor” exceeding the “required protection factor” from the following list.
    Designated protection factor * List (excerption)

    Type of respiratory protective equipment				Designated protection factor
    Dust protective mask	Replaceable type	Full-face type face	RS3 or RL3	50
    			RS2 or RL2	14
    			RS1 or RL1	4
    		Half-face type face	RS3 or RL3	10
    			RS2 or RL2	10
    			RS1 or RL1	4
    	Disposable type		DS3 or DL3	10
    			DS2 or DL2	10
    			DS1 or DL1	4
    Respiratory protective equipment with electric blower	Full-face type face	Class S	PS3 or PL3	1,000
    		Class A	PS2 or PL2	90
    		Class A or Class B	PS1 or PL1	19
    	Half-face type face	Class S	PS3 or PL3	50
    		Class A	PS2 or PL2	33
    		Class A or Class B	PS1 or PL1	14
    	Hood type or face shield type	Class S	PS3 or PL3	25
    		Class A		20
    		Class S or Class A	PS2 or PL2	20
    		Class S, Class A or Class B	PS1 or PL1	11

    For further details, refer to the website of the Ministry of Health, Labour and Welfare
    ( https://www.mhlw.go.jp/stf/newpage_12725.html )

• [5] (When getting the workers to use respiratory protective equipment with face) Conduct a fit test once per 1 year or less.

  

  Check that the respiratory protective equipment is put on properly.

  Learn more about fit test

   

Engineering measures for welding operation

• General ventilation system

  The air volume of this ventilation system should be appropriate for the size of the workplace and the measured concentration.

  

• Push-pull type ventilation system

  It is a ventilation system that prevents fumes from diffusing to the environment and maintains the safety and workability.

  

  Local exhaust ventilation system

  It is a small system that can conduct exhaust ventilation when the working range is limited.