Advisory issued on gas mask clamping rings; four models and products affectedAn advisory has been issued about masks that protect you from harmful gas
On November 2, MHLW issued an advisory on the use of the clamping ring of gas masks. It was found that on some gas masks made by Koken Ltd. (Chiyoda-ku, Tokyo), the fit between the clamping ring used to attach the absorbent canister and the mask body is stiff, making the ring difficult to tighten in some cases. According to the advisory, if the mask is used without the clamping ring properly attached, an airtight seal between the mask body and the canister cannot be ensured, which may affect the performance of the gas mask.
- ○Applies: R-5-08 model (No. TN421; manufactured July to September 2026)
- ○Applies: R-5-RA-08 model (No. TN421; manufactured August 2026)
- ○Applies: R-5X-08 model (No. TN422; manufactured August 2026)
- ○Applies: Boxed R-5 set and replacement parts set (manufactured August to September 2026)
Key points
- The affected products are the R-5-08 model (type approval No. TN421; manufactured July to September 2026)
- Also affected are the R-5-RA-08 model (No. TN421; August 2026) and the R-5X-08 model (No. TN422; August 2026)
- The boxed R-5 set and replacement parts set (manufactured August to September 2026) is also affected
- Users are asked to check the gas masks they have on hand and, if theirs is affected, to contact the manufacturer promptly
- The advisory was issued by the Environmental Improvement and Exposure Control Office, Chemical Hazards Control Division, Industrial Safety and Health Department, Labour Standards Bureau, MHLW
What to do in practice
- Check the model name, type approval number and manufacturing period of the gas masks at the worksite, and contact the manufacturer if any are affected
- Record the results of this check in the protective equipment inspection records, and remind workers how to confirm that the clamping ring is firmly tightened
Masks worn in factories and similar places to avoid breathing in harmful gas are called gas masks. A part called an absorbent canister, which cleans the air, is attached to the mask with a ring that you tighten. On November 2 it was found that on some masks this ring is stiff and hard to tighten. If it is not tightened properly, harmful air can get in through the gap. People are being asked to check the masks they have and to contact the maker if theirs is one of them.
- 1. LookLook at the model of the masks at the worksite and when they were made
- 2. CompareCheck whether they match the models listed in the advisory
- 3. ContactIf they match, contact the company that made them
- 4. CheckAs a routine, check that the ring is firmly tightened
Points
- A gas mask is equipment used so that you do not breathe in gas that is bad for your body
- It was found that the ring used to tighten the part is stiff and hard to turn on some masks
- If your mask is one of them, contact the company that made it
What the words mean
- Gas mask
- Equipment that covers the mouth and nose so that you do not breathe in gas that is bad for your body
- Absorbent canister
- The part attached to the mask that removes the bad air
- Ministry of Health, Labour and Welfare (MHLW): MHLW: Advisory on the use of the clamping ring of gas masks
This article summarizes and explains materials published by government agencies and is not advice on any individual case. Rules can change, so for actual procedures and decisions always check the latest original materials and consult professionals such as tax accountants or labor and social security attorneys. English, Simplified Chinese and Traditional Chinese versions are translations prepared from the Japanese articles for convenience. If anything differs, the Japanese text and the original source take precedence.