United Kingdom: Welding PAPR Rules, Standards and HSE Guidance

In the UK, powered air-purifying respirators (PAPR) for welding sit under the COSHH Regulations 2002, enforced by the Health and Safety Executive (HSE). Since HSE’s 2019 safety bulletin reclassified all welding fume — including mild steel — as a human carcinogen, indoor welding requires engineering controls (LEV), supplemented by RPE with a minimum assigned protection factor of 20 where control is incomplete. Loose-fitting PAPR hoods and helmets certified to EN 12941 (TH2/TH3) meet APF 20 without fit testing; tight-fitting power-assisted masks to EN 12942 (TM classes) require face-fit testing. Since 1 October 2024, both UKCA and CE markings are accepted indefinitely on the GB market.

Which rules apply

Workplace exposure to welding fume in Great Britain is regulated under the Control of Substances Hazardous to Health Regulations 2002 (COSHH), as amended, enforced by the Health and Safety Executive (HSE). HSE’s COSHH essentials guidance states this framework governs how employers must control exposure to hazardous substances and select respiratory protective equipment (RPE). The Approved Codes of Practice (ACOPs) supporting COSHH — together with those under the lead, asbestos, confined-spaces and ionising-radiations regulations — stipulate that tight-fitting RPE must be fit tested as part of selection. The two core HSE guidance documents for RPE are HSG53 ‘Respiratory protective equipment at work: A practical guide’ (fourth edition, 2013) and INDG479 ‘Guidance on respiratory protective equipment (RPE) fit testing’ (updated October 2025). HSE guidance is not itself compulsory, but HSE states that following it ‘will normally be doing enough to comply with the law’, and inspectors may refer to it as illustrating good practice.

Certification for PAPR: UKCA and CE after Brexit

PPE placed on the Great Britain market — including PAPR — must meet Regulation (EU) 2016/425 as assimilated into UK law, enforced through the Personal Protective Equipment (Enforcement) Regulations 2018. Manufacturers can use either the UKCA marking or the CE marking: government guidance confirms the Product Safety and Metrology etc. (Amendment) Regulations 2024 (in force 1 October 2024) ‘extend recognition of CE marking indefinitely in GB’, so both markings remain valid beyond 31 December 2024. UK conformity assessment is carried out by ‘approved bodies’ appointed by the Secretary of State, listed on the government’s find-a-conformity-assessment-body register. In Northern Ireland, EU rules continue to apply, and qualifying Northern Ireland goods can be sold in the rest of the UK without additional approvals. Note that HSG53 warns a conformity marking ‘does not indicate that an RPE device is automatically adequate and suitable’ for a specific task — selection remains the employer’s responsibility.

Employer duties: the RPE programme under COSHH

HSG53 states that under the law ‘RPE is the last line of protection’: it should only be used where an inhalation risk remains after other reasonably practicable controls, as interim or emergency cover, or for short-term work. Selected RPE must be both ‘adequate’ (right for the hazard) and ‘suitable’ (right for the wearer, task and environment). Employers must ensure reusable RPE undergoes thorough examination and, where appropriate, testing at suitable intervals — HSG53 says ‘this should be monthly, or every three months if used less frequently’ — and records of examinations, tests and repairs should be retained ‘for at least five years’. Wearers must be trained, supervised and medically fit to wear RPE. HSE’s COSHH essentials sheet R3 adds practical points for powered and air-fed equipment: check airflow every time before use, replace valves, face seals and worn parts, keep a small stock of replacement parts, and check expiry dates on RPE and filters.

Welding fume: HSE’s enforcement position

In February 2019, HSE issued Safety Bulletin STSU1 – 2019 announcing ‘a strengthening of HSE’s enforcement expectation for all welding fume, including mild steel welding’, after new scientific evidence led to welding fume being reclassified as a human carcinogen. The bulletin states that general ventilation is not sufficient: ‘Control of the cancer risk will require suitable engineering controls for all welding activities indoors eg Local Exhaust Ventilation (LEV)’, and ‘where LEV alone does not adequately control exposure, it should be supplemented by adequate and suitable respiratory protective equipment (RPE)’. HSE adds that it ‘will no longer accept any welding undertaken without any suitable exposure control measures in place, as there is no known level of safe exposure’ — regardless of how short the welding task is. For outdoor welding, HSE’s guidance states LEV will not work, so workers should use suitable RPE. Where RPE is used, HSE requires it to be supported by an RPE programme.

Selecting RPE for welding: APF 20 as the baseline

HSE’s welding guidance sets out a practical selection rule: ‘use an FFP3 disposable mask or half-mask with P3 filter, for work of up to an hour’, and ‘battery-powered air-fed protective equipment for longer duration work, with a minimum assigned protection factor of 20 (APF20)’. An APF of 20 means the air inside the facepiece is expected to contain no more than one-twentieth of the contaminant concentration outside. HSE’s COSHH essentials sheet R3 lists the devices that achieve APF 20, including the ‘powered hood model TH2 EN 12941’ and the ‘power-assisted mask model TM2 EN 12942’, while cautioning that these filtering devices are not suitable for confined spaces. HSG53’s tables note that P1 and P2 particle filters ‘are not recommended for fumes unless stated’. Employers may also choose equipment with higher protection than the minimum: TH3 hoods and TM3 masks carry an APF of 40 in the UK scheme.

EN 12941 vs EN 12942 — and who needs a fit test

The two standards divide powered filtering devices by how they connect to the wearer. EN 12941 covers powered filtering devices incorporating a helmet or a hood — loose-fitting devices classified TH1, TH2 and TH3, with UK assigned protection factors of 10, 20 and 40 respectively per HSG53. EN 12942 covers power-assisted filtering devices incorporating full face, half or quarter masks — tight-fitting devices classified TM1, TM2 and TM3, also with APFs of 10, 20 and 40. The fit-testing consequence is stated in INDG479: ‘Powered or constant-flow airline BA RPE with loose-fitting hoods or helmets do not require fit testing’, but ‘tight-fitting powered or constant-flow airline BA RPE under positive pressure still requires fit testing as studies have shown that during heavy exertion, inward leakage is possible.’ Fit tests should be repeated when the model, size or material changes, or when the wearer’s face changes. Competence can be demonstrated through the Fit2Fit accreditation scheme, run by the British Safety Industry Federation and supported by HSE; HSE states the scheme is not compulsory. Loose-fitting EN 12941 hoods are the route HSE guidance identifies for wearers with facial hair, since tight-fitting RPE wearers must be clean shaven.

What changed recently and what to watch

Three dates matter for anyone maintaining a UK welding RPE programme. First, February 2019: bulletin STSU1 – 2019 remains HSE’s stated enforcement position that all welding fume, including mild steel, must be controlled, with no known safe level of exposure. Second, 1 October 2024: the Product Safety and Metrology etc. (Amendment) Regulations 2024 made CE-marking recognition in Great Britain indefinite, so employers can continue buying CE-marked PAPR systems and spare parts alongside UKCA-marked ones; the gov.uk guidance reflecting this was last updated 24 March 2025. Third, October 2025: HSE reissued INDG479, its fit-testing guidance, so fit-test providers and RPE programmes should be working from the October 2025 version. Note that HSG53 (fourth edition, 2013) predates Brexit and still describes CE marking under the older PPE Regulations 2002; current market-placement rules come from assimilated Regulation 2016/425 and gov.uk guidance. This page is current as of July 2026.

Sources & disclaimer

This page is information, not legal or safety advice. It summarises the cited public sources as of the date above; regulations change — verify against the primary source before relying on it. Product-level approval status is covered by our four-tier compatibility system.