United States: Welding PAPR compliance — OSHA 29 CFR 1910.134, NIOSH 42 CFR 84 and the hexavalent chromium rules

In the United States, respirator use at work is governed by OSHA’s Respiratory Protection standard (29 CFR 1910.134), which requires employers to run a written programme and to select only NIOSH-certified respirators. NIOSH approves PAPRs under 42 CFR Part 84 and lists them, with TC approval numbers, on its Certified Equipment List. For welders the key selection question is the assigned protection factor: loose-fitting facepiece PAPRs carry an APF of 25, while helmet/hood PAPRs carry 25 or 1,000 depending on whether the employer holds manufacturer test evidence. Welding on stainless and other chromium alloys can additionally trigger OSHA’s hexavalent chromium standards. Content current as of July 2026.

Which rules apply

Two federal systems interlock. The Occupational Safety and Health Administration (OSHA) regulates how respirators are used at work: its Respiratory Protection standard, 29 CFR 1910.134, applies to general industry, and OSHA’s guidance states the same final standard (via 29 CFR 1926.103) covers construction, longshoring, shipyard and marine terminal workplaces. The National Institute for Occupational Safety and Health (NIOSH) regulates which respirators may be sold as approved devices, under 42 CFR Part 84. The two connect at 1910.134(d)(1)(ii): the employer must select a NIOSH-certified respirator and use it in compliance with the conditions of its certification. On top of the general standard sit substance-specific rules that matter to welders — the hexavalent chromium standards (29 CFR 1910.1026 general industry, 1926.1126 construction, 1915.1026 shipyards) — and the welding standard itself, 29 CFR 1910.252, whose paragraph (c) sets health-protection and ventilation requirements for welding, cutting and brazing.

How PAPR approval works: NIOSH, 42 CFR 84 and TC numbers

NIOSH (through its National Personal Protective Technology Laboratory, NPPTL) approves respiratory protective devices under 42 CFR Part 84: applications under Subpart B, approval and disapproval under Subpart D, quality control under Subpart E, and air-purifying particulate respirators — including powered ones — under Subpart K. Every approved device carries an approval label meeting 42 CFR 84.33: the NIOSH emblem and HHS seal, the manufacturer’s name and address, an approval number prefixed “TC”, and any restrictions NIOSH imposes on use. Powered air-purifying particulate respirators sit under approval schedule 21C, so their approval numbers take the form TC-21C-####; abbreviated labels also appear on components such as filters. Particulate PAPRs are approved in class HE (high-efficiency filters) and, since 2020, the PAPR100-N and PAPR100-P classes. The authoritative way to check any approval is the NIOSH Certified Equipment List (CEL), a public search tool covering current and obsolete approvals by TC number, manufacturer and respirator type.

Employer duties: the written respiratory protection programme

Where respirators are required, 1910.134(c) obliges the employer to establish a written programme with worksite-specific procedures covering: respirator selection; medical evaluations; fit testing of tight-fitting facepieces; routine and emergency use procedures; cleaning, disinfecting, storing, inspecting, repairing and maintaining respirators; breathing-air quality (for supplied-air devices); training on respiratory hazards and on respirator use, limitations and maintenance; and regular evaluation of programme effectiveness. Medical evaluation must happen before an employee is fit tested or first uses a respirator at work (1910.134(e)(1)). Fit testing under paragraph (f) applies only to tight-fitting facepieces — initially, when the facepiece changes, and at least annually. Loose-fitting PAPRs, the type most welding headtops belong to, therefore do not require fit testing, though medical evaluation and training still apply under the current standard. Training must be provided before first use and in a manner the employee understands (1910.134(k)).

Welding fume: ventilation triggers and the hexavalent chromium standards

OSHA’s welding standard, 1910.252(c), requires ventilation sufficient to keep fumes and gases below the limits in 1910.1000, and specifically requires mechanical ventilation (minimum 2,000 cubic feet per minute per welder) where there is less than 10,000 cubic feet of space per welder or the ceiling is below 16 feet, with stated exceptions for local exhaust or approved respirators. Where ventilation cannot control the exposure, respiratory protection under 1910.134 applies. Welding on stainless steel and other chromium-containing alloys is identified by OSHA as a significant source of hexavalent chromium (Cr(VI)) exposure. The Cr(VI) standards set a permissible exposure limit of 5 micrograms per cubic metre of air as an 8-hour time-weighted average, with an action level of 2.5 µg/m³. Paragraph (g) of 1910.1026 requires a 1910.134-compliant respiratory protection programme wherever respirators are needed — for example while engineering controls are installed, where feasible controls cannot reach the PEL, and in emergencies. Medical surveillance is triggered for employees exposed at or above the action level for 30 or more days a year.

Selection and protection factors: the APF 25 vs 1,000 question

Employers must select respirators using the assigned protection factors (APFs) in Table 1 of 1910.134(d)(3)(i)(A). For PAPRs the table gives: half mask 50; full facepiece 1,000; helmet/hood “25/1,000”; loose-fitting facepiece 25. The footnote is the crux for welding headtops: an APF of 1,000 for a helmet/hood PAPR applies only where the employer has evidence from the manufacturer that testing demonstrates performance at a level of 1,000 or greater — best shown by a workplace protection factor (WPF) or simulated workplace protection factor (SWPF) study or equivalent. Absent that evidence, helmet/hood PAPRs must be treated as loose-fitting facepiece respirators with an APF of 25. The standard defines a helmet as a rigid inlet covering that also protects against impact and penetration, a hood as covering the head and neck completely, and a loose-fitting facepiece as forming only a partial seal. The stakes are set by the maximum use concentration (MUC = APF × exposure limit): against the Cr(VI) PEL of 5 µg/m³, APF 25 gives an MUC of 125 µg/m³, while APF 1,000 gives 5,000 µg/m³.

Checking approvals and keeping a PAPR in its approved configuration

OSHA requires that a NIOSH-certified respirator be used in compliance with the conditions of its certification (1910.134(d)(1)(ii)), and NIOSH’s approval label is where those conditions live: 42 CFR 84.33 requires the label to state the approval number and any NIOSH-imposed restrictions or limitations, and permits labels to be used only by the certificate holder they were issued to. Manufacturers must maintain quality control so that production matches the approved specifications, and abbreviated approval markings appear on components such as filters. NIOSH publishes guidance on reading approval labels (document 2011-179). For anyone buying replacement parts — filters, breathing tubes, headtops — this is the compliance mechanism that matters: the approval attaches to the device as certified, so components should be checked against the approval label and the entry on the NIOSH Certified Equipment List rather than assumed interchangeable. The CEL can be searched by TC number (for particulate PAPRs, TC-21C-####), manufacturer, respirator type and facepiece type, and distinguishes current from obsolete approvals.

What changed recently and what is changing

Two developments frame the current picture. First, on 14 April 2020 NIOSH published an interim final rule amending 42 CFR Part 84: it consolidated all air-purifying particulate respirator requirements into Subpart K, removed the obsolete former Subpart KK (dust/fume/mist, pesticide and paint-spray respirators), and created the PAPR100 class — PAPR100-N (not for oil aerosols) and PAPR100-P (strongly oil-resistant) — intended to give equivalent protection to PAPR HE devices while enabling smaller, lighter designs by replacing the silica-dust test with aerosol tests. Second, on 1 July 2025 OSHA published a proposed rule (Docket OSHA-2025-0006) that would remove the medical evaluation requirement in 1910.134 for employees using only filtering facepiece respirators or loose-fitting PAPRs, on OSHA’s preliminary view that the physiological burden of these devices is low; other respirator types would be unaffected. Secondary reporting indicates the comment period was extended and virtual public hearings were scheduled from August 2026. As of July 2026 this remains a proposal: the existing medical evaluation requirements still apply, including to loose-fitting PAPR users.

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.