PPE protection levels overview

Under 1910.120 App B, Level A protection should be selected when the highest level of skin, eye, and respiratory protection is needed because the substance is highly hazardous, present at high concentrations, or there is a high potential for splash, immersion, or unexpected vapors or gases.

• Key triggers include identified or suspected substances that can be absorbed through the skin or that present high airborne concentrations, operations in confined or poorly ventilated areas, or tasks with a high splash/immersion risk. See the guidance on selecting Level A in Appendix B to 1910.120 and the overall PPE-selection requirements in 1910.120.

Under 1910.120 App B, Level B protection is appropriate when the highest level of respiratory protection is required but less skin protection is needed (for example, when the atmosphere is highly hazardous by inhalation but does not present a severe skin absorption hazard).

• Typical indicators include identified high inhalation hazards (including IDLH conditions) where skin contact is unlikely or not highly hazardous, or when oxygen levels are below 19.5% but skin hazards are lower. See the Level B criteria in Appendix B to 1910.120 and the PPE-selection responsibilities in 1910.120.

Under 1910.120 App B, Level C protection is justified when the airborne contaminants and concentrations are known, the contaminants will not adversely affect or be absorbed through exposed skin, and an approved air-purifying respirator can remove the contaminants.

• Level C can be used only if all criteria for using air-purifying respirators are met; otherwise, a higher level of respiratory protection is necessary. See the Level C criteria in Appendix B to 1910.120 and the general PPE selection duties in 1910.120.

Under 1910.120 App B, Level D protection is acceptable only for nuisance contamination when the atmosphere contains no known hazards and the work precludes splashes, immersion, or inhalation of hazardous levels of chemicals.

• Level D is essentially a work uniform with minimal protective value and should not be used if inhalation, skin absorption, or splash hazards exist. See the Level D description in Appendix B to 1910.120.

Under 1910.120 App B, typical Level A equipment includes a positive-pressure, full face-piece SCBA (or positive pressure supplied-air respirator with escape SCBA), a totally-encapsulating chemical-protective suit, inner and outer chemical-resistant gloves, chemical-resistant boots with steel toe and shank, coveralls/long underwear as needed, and, optionally, a hard hat under the suit.

• Appendix B lists specific items and emphasizes that exact materials and seams must be evaluated for the specific hazard. See the Level A equipment list in Appendix B to 1910.120 and employer PPE-selection responsibilities in 1910.120.

Under 1910.120 App B, typical Level B equipment includes a positive-pressure, full-facepiece SCBA (or positive pressure supplied-air respirator with escape SCBA), hooded chemical-resistant clothing (overalls, jacket, or splash suit), chemical-resistant gloves (inner and outer), chemical-resistant boots with steel toe and shank, disposable outer boot covers if needed, and a hard hat and face shield where appropriate.

• Level B provides maximum respiratory protection with reduced skin protection compared to Level A, so employers must confirm skin hazards are limited before choosing Level B. See the Level B equipment list in Appendix B to 1910.120.

Under 1910.120 App B, Level C protection typically includes full-face or half-mask air-purifying respirators (NIOSH-approved), hooded chemical-resistant clothing (overalls or splash suits), chemical-resistant gloves (inner and outer), chemical-resistant boots with steel toe and shank if required, and, where needed, escape masks, hard hats, and face shields.

• Level C should only be used when the contaminant types and concentrations are known and an air-purifying respirator can be used safely. See the Level C equipment list and conditions in Appendix B to 1910.120.

Under 1910.120 App B, Level D protection generally consists of coveralls, gloves, chemical-resistant steel-toe boots or shoes, disposable outer boot covers where applicable, safety glasses or splash goggles, a hard hat where needed, escape masks, and face shields if required.

• Remember Level D is for nuisance contamination only and provides minimal barrier protection. See the Level D list in Appendix B to 1910.120.

Under 1910.120 App B, yes—combinations of PPE drawn from different levels (A, B, C, or D) may be more suitable and can be used to match the specific hazards and tasks at the site.

• Appendix B cautions that the listed combinations do not automatically ensure protection; employers must evaluate material performance, seams, and task conditions and re-select PPE as more hazard information becomes available. See the guidance on combining PPE in Appendix B to 1910.120 and employer obligations in 1910.120.

Under 1910.120 App B, 'breakthrough time' is the time it takes for a hazardous chemical to permeate through a protective material; PPE should be chosen so the material's breakthrough time exceeds the expected work duration for the task.

• If continuous protection is not possible for a particular substance, select materials with adequate breakthrough times or plan for task duration and rotation so exposure is controlled. See the discussion of material-specific protection and breakthrough time in Appendix B to 1910.120.

Under 1910.120 App B, seam strength and material durability are important because tears or seam failures can allow hazardous substances to contact skin or clothing, defeating the protective value of the PPE.

• Employers should evaluate tear strength, seam construction, and overall durability relative to the employee's tasks and consider layered protection when necessary to protect both the worker and inner PPE. See the appendix discussion on matching PPE durability to tasks in Appendix B to 1910.120.

Under 1910.120 App B, employers should consider the effects of PPE on heat stress and task duration because fully encapsulating or layered suits can increase heat strain and limit safe work periods.

• Employers may need to use work/rest cycles, cooling measures, rotate personnel, or choose alternative protective configurations to balance protection and heat-stress safety; Appendix B explicitly calls out heat stress as a selection factor. See Appendix B to 1910.120 and the general PPE obligations in 1910.120.

Under 1910.120 App B, disposable protective suits, gloves, and boots may be worn over totally-encapsulating suits depending on suit construction and the task, and employers may use outer disposables to protect expensive inner garments or add protection layers.

• Appendix B notes this as an option and emphasizes evaluating the combined performance (including seams and breathability). See the note about disposable garments in Appendix B to 1910.120.

Under 1910.120 App B, PPE selection should be an ongoing process and re-evaluated as more information about site hazards and PPE performance becomes available, with upgrades or downgrades made to match tasks and conditions.

• Appendix B advises supervisors to make decisions to up-grade or down-grade protection as site information changes. Employers should document evaluations and follow the employer duties in 1910.120.

Under 1910.120 App B, air-purifying respirators may be used for Level C only when the contaminant types and concentrations are known and measured, the contaminants will not adversely affect or be absorbed through exposed skin, and all criteria for air-purifying respirator use are met.

• Appendix B requires that the air contaminants be identified, concentrations measured, and a suitable air-purifying respirator available before selecting Level C. See the Level C criteria in Appendix B to 1910.120 and remember to follow the respiratory protection duties in 1910.120.

Under 1910.120 App B, Level B should be considered when the atmosphere contains less than 19.5% oxygen because that condition indicates a need for supplied-air or SCBA respiratory protection rather than air-purifying respirators.

• Appendix B explicitly lists oxygen-deficient atmospheres (< 19.5% oxygen) as a trigger for Level B. For related guidance on oxygen-deficient atmospheres and respiratory protection, see Appendix B to 1910.120 and OSHA's interpretation on oxygen-deficient atmospheres in HVAC contexts at https://www.osha.gov/laws-regs/standardinterpretations/2024-07-16.

Under 1910.120 App B, operations in confined or poorly ventilated areas justify selecting higher protection levels (often Level A) until the absence of conditions requiring that level has been determined.

• Appendix B states that if confined, poorly ventilated areas are present and hazards have not yet been ruled out, employers should use the highest protection necessary and re-evaluate as more information becomes available. See the confined-space guidance in Appendix B to 1910.120.

Under 1910.120 App B, NFPA standards such as NFPA 1991, 1992, and 1993 are recommended references because they set documentation and performance requirements for chemical-protective suits and label compliant suits accordingly.

• Appendix B recommends using chemical-protective suits that meet these NFPA standards and explains they apply manufacturing performance requirements. See the NFPA reference in Appendix B to 1910.120.

Under 1910.120 App B, a hard hat worn under an encapsulating suit is listed as optional (as applicable) and is not automatically required; employers must assess head hazards and provide head protection when needed.

• Appendix B shows a hard hat as optional under Level A and other levels where noted. For the employer's duty to assess and require head protection where falling object hazards exist, see Appendix B to 1910.120 and OSHA's head-protection interpretation at https://www.osha.gov/laws-regs/standardinterpretations/2024-06-06-2.

Under 1910.120 App B, employers should choose inner and outer glove and boot combinations based on the specific chemical hazards, material compatibility (including permeation and breakthrough times), and durability required for the task; layered gloves and boots are commonly used to improve protection and preserve inner PPE.

• Appendix B lists inner and outer chemical-resistant gloves and outer boots as components of Levels A–C and advises evaluating material performance and seams relative to the hazard. See Appendix B to 1910.120.

Under 1910.120 App B, escape masks or an escape SCBA are required or recommended when there is a potential for sudden hazardous releases or the need to evacuate through a contaminated atmosphere; they appear in the equipment lists for Levels B and C (escape SCBA for Level A/B respiratory options and escape masks for Level C/D where indicated).

• Appendix B lists escape devices as part of the recommended gear for appropriate levels and notes employers must evaluate the need based on potential exposures and emergency escape requirements. See the equipment listings in Appendix B to 1910.120.

Under 1910.120 App B, employers should document hazard identification, material-performance data (including breakthrough times and seam strength), reasons for selecting specific PPE levels or combinations, and plans to re-evaluate PPE as site information changes; the appendix frames PPE selection as a documented, ongoing process tied to the employer's obligations under 1910.120.

• See the guidance in Appendix B to 1910.120 and the overall PPE and site-control requirements in 1910.120.