When workers face respiratory hazards — dust, fumes, gases, vapours, or oxygen-deficient atmospheres — the right respiratory protective equipment (RPE) can mean the difference between a healthy workforce and serious illness or death.
HSG53 is the HSE's guidance document on respiratory protective equipment at work. It explains how to select, use, and maintain RPE to protect workers from airborne hazards.
HSG53 isn't a legal requirement itself — but following it helps you comply with the law. The guidance supports the Control of Substances Hazardous to Health Regulations 2002 (COSHH) and the Personal Protective Equipment at Work Regulations 1992.
What is HSG53?
HSG53 — "Respiratory protective equipment at work: A practical guide" — is HSE guidance published to help employers understand their duties regarding RPE. It covers:
- When RPE is needed
- How to select the right type for the hazard
- Fit testing requirements
- Training workers to use RPE correctly
- Maintenance, storage, and inspection
- Programme management
The guidance applies to all workplaces where respiratory hazards exist, from construction sites and manufacturing plants to laboratories and healthcare settings.
When is RPE required?
RPE should only be used as a last resort — after other control measures have been considered. This is a fundamental principle that many businesses get wrong.
The hierarchy of controls
Before reaching for RPE, work through the hierarchy of controls:
1. Elimination — Remove the hazardous substance entirely
- Can you use a different process that doesn't create the hazard?
- Can the work be done differently?
2. Substitution — Replace with something less hazardous
- Can you use a water-based product instead of solvent-based?
- Can you use a less dusty material?
3. Engineering controls — Contain or extract the hazard
- Local exhaust ventilation (LEV)
- Enclosed systems
- Wet suppression methods
4. Administrative controls — Change how work is done
- Reduce exposure time
- Limit the number of people exposed
- Provide designated areas for hazardous work
5. RPE — Protect the individual worker
- Only when other controls cannot adequately reduce exposure
- Always in combination with other measures, not instead of them
RPE is personal protection — it only protects the wearer if worn correctly. Engineering controls like LEV protect everyone in the area without relying on individual behaviour. That's why the hierarchy places RPE last, not first.
When RPE becomes necessary
You'll need RPE when:
- Engineering controls alone cannot reduce exposure below the workplace exposure limit (WEL)
- Engineering controls are not reasonably practicable
- As an interim measure while other controls are being implemented
- For non-routine work where permanent controls aren't appropriate
- For emergency situations or rescue operations
Types of respiratory protective equipment
RPE falls into two main categories: filtering devices (which clean the air you breathe) and breathing apparatus (which supply clean air from an independent source).
Filtering devices
These remove contaminants from the air before you breathe it. They're lighter and more practical for many applications but have limitations.
Filtering Facepieces vs Half Masks
Filtering Facepieces (FFP)
- •Disposable — single use or single shift
- •Filter and facepiece combined
- •Lightweight and convenient
- •Lower protection factors (APF 4-20)
- •Cannot be fit tested with quantitative methods
- •Suitable for lower hazard levels
Half Masks with Replaceable Filters
- •Reusable facepiece
- •Changeable filters for different hazards
- •More durable and cost-effective long term
- •Higher protection factors (APF 10-20)
- •Can be quantitatively fit tested
- •Better for regular or prolonged use
Bottom line: Choose based on the required protection factor, how often RPE is needed, and the specific hazards present. Neither is inherently better — it depends on your situation.
Filtering facepiece respirators (FFP1, FFP2, FFP3)
These disposable masks are classified by their filtering efficiency:
| Class | Minimum Filter Efficiency | Assigned Protection Factor | Typical Use |
|---|---|---|---|
| FFP1 | 80% | 4 | Low-hazard dusts, nuisance odours |
| FFP2 | 94% | 10 | Medium-hazard dusts and mists |
| FFP3 | 99% | 20 | High-hazard dusts, fumes, biological agents |
FFP masks only protect against particles (dusts, mists, fumes). They do NOT protect against gases and vapours. For gas/vapour hazards, you need a respirator with an appropriate gas filter.
Half mask respirators
Cover the nose and mouth. Used with replaceable filters:
- Particle filters (P1, P2, P3) — for dusts, mists, fumes
- Gas filters (A, B, E, K, etc.) — for specific gas/vapour types
- Combined filters — for mixed hazards
Assigned protection factor: typically 10-20 depending on the filter.
Full face masks
Cover the entire face including eyes. Provide:
- Higher protection factors (up to 40)
- Eye protection from irritant gases
- Better seal than half masks
- Wider field of vision than half masks
Powered air-purifying respirators (PAPR)
A battery-powered fan draws air through filters and delivers it to a hood, helmet, or facepiece. Benefits:
- No breathing resistance — easier to wear for long periods
- Often higher protection factors (up to 40)
- Suitable for people who cannot achieve a good face seal
- Can be used by people with facial hair (loose-fitting versions)
Breathing apparatus (BA)
Supplies clean air from an independent source — either a compressed air cylinder or an airline connected to a remote supply.
Self-contained breathing apparatus (SCBA)
- Worker carries air supply on their back
- Complete independence from ambient atmosphere
- Protection factor of 40+
- Limited by air supply duration
- Used for emergency response, confined spaces, IDLH atmospheres
Airline breathing apparatus
- Air supplied through a hose from a remote source
- Unlimited air supply (within hose length)
- Worker mobility restricted by airline
- Various facepiece options available
Breathing apparatus is essential when the atmosphere is immediately dangerous to life or health (IDLH), oxygen-deficient (below 19.5%), or when the hazard cannot be adequately controlled with filtering RPE. Using filtering RPE in these situations can be fatal.
Selecting the right RPE
Choosing appropriate RPE requires systematic assessment. Get it wrong and workers may be inadequately protected despite wearing equipment.
Step 1: Understand the hazard
Identify:
- What is the hazardous substance? (dust, gas, vapour, biological agent)
- What concentration is present or expected?
- What is the workplace exposure limit (WEL)?
- What form is the hazard in? (particulate, gas, mist)
- Is the atmosphere oxygen-deficient?
Step 2: Calculate required protection
Protection Factor = Hazardous concentration / Acceptable concentration
The RPE you choose must have an Assigned Protection Factor (APF) at least as high as the protection factor required.
| RPE Type | Assigned Protection Factor |
|---|---|
| Filtering facepiece FFP1 | 4 |
| Filtering facepiece FFP2 | 10 |
| Filtering facepiece FFP3 | 20 |
| Half mask with P3 filter | 20 |
| Full face mask with P3 filter | 40 |
| Powered respirator with hood | 40 |
| SCBA with full face mask | 40+ |
Step 3: Consider practical factors
- Duration of use — Can workers wear this for the required time?
- Physical demands — Does the work involve heavy exertion?
- Communication needs — Does the worker need to talk to others?
- Compatibility — Does it work with other PPE (hard hats, eye protection)?
- Environment — Temperature, humidity, confined spaces?
- Facial hair — Tight-fitting RPE won't seal on beards
Step 4: Check the filter type
For filtering RPE, ensure the filter is appropriate:
| Filter Type | Colour Code | Protects Against |
|---|---|---|
| P | White | Particles (dusts, mists, fumes) |
| A | Brown | Organic gases/vapours (solvents) |
| B | Grey | Inorganic gases (chlorine, hydrogen sulphide) |
| E | Yellow | Acidic gases (sulphur dioxide) |
| K | Green | Ammonia |
| AX | Brown | Low-boiling organic compounds |
| Hg | Red | Mercury |
Filters have a limited service life. Particle filters load up and breathing resistance increases. Gas filters become saturated and "breakthrough" occurs. Always follow manufacturer guidance on filter replacement and never use filters beyond their expiry date.
Fit testing requirements
A respirator is only as effective as its seal against the face. Fit testing ensures the selected RPE fits the individual wearer properly.
Who needs fit testing?
Everyone who wears tight-fitting RPE must be fit tested. This includes:
- Filtering facepieces (FFP masks)
- Half masks
- Full face masks
Loose-fitting RPE (hoods, helmets, blouses) does not require fit testing but must still be properly sized and fitted.
Types of fit test
Qualitative fit testing
- Uses the wearer's sense of taste or smell
- Bitter or sweet aerosol introduced while wearing the mask
- If the wearer can taste/smell it, the mask doesn't fit
- Suitable for half masks and filtering facepieces
- Pass/fail result only
Quantitative fit testing
- Uses instrumentation to measure leakage
- Provides a numerical "fit factor"
- Required for full face masks
- Recommended for half masks where high protection needed
- More reliable and objective than qualitative testing
When to repeat fit testing
Fit testing must be repeated:
- When the make or model of RPE changes
- When the wearer's face changes significantly (weight change, dental work, scarring)
- Periodically (HSE recommends every 1-3 years)
- If the wearer experiences problems with fit
Fit testing is not a one-time event. Faces change, and the same mask model from a different batch may fit differently. Regular testing ensures ongoing protection.
Facial hair and fit testing
Tight-fitting RPE will not seal properly against a beard, stubble, or sideburns that pass under the mask seal. Options include:
- Workers remain clean-shaven in the seal area
- Use loose-fitting RPE (powered hoods or helmets)
- Use airline or SCBA with loose-fitting headtops
Training requirements
RPE only protects workers if used correctly. Training is a legal requirement under both COSHH and the PPE Regulations.
What training must cover
- Why RPE is needed — the hazards it protects against
- How to put it on correctly — achieving a proper seal
- How to check the fit — user seal checks
- Limitations of the RPE — what it does and doesn't protect against
- When to replace filters or disposable masks
- How to store and maintain the equipment
- What to do if problems occur
User seal checks
Every time a tight-fitting respirator is put on, the wearer should perform a user seal check:
Positive pressure check:
- Cover the exhalation valve
- Exhale gently
- The facepiece should bulge slightly without air escaping
Negative pressure check:
- Cover the filter(s) or inlet
- Inhale gently
- The facepiece should collapse slightly and stay collapsed
User seal checks are NOT a substitute for fit testing. They only confirm the mask is properly donned on that occasion — they don't verify the mask is the right size and model for that person.
Maintenance, storage, and inspection
RPE must be properly maintained to remain effective. Neglected equipment may look fine but provide no protection.
Maintenance requirements
Disposable RPE:
- Single use — discard after each use or shift
- Never attempt to clean and reuse
- Replace immediately if damaged, contaminated, or breathing becomes difficult
Reusable RPE:
- Clean after each use following manufacturer instructions
- Inspect for damage — cracks, deterioration, damaged straps
- Replace worn or damaged parts
- Replace filters according to schedule or when breakthrough occurs
- Store properly between uses
Storage requirements
- Store in a clean, dry location
- Protect from direct sunlight and heat
- Keep away from contaminants
- Store in a container or bag to prevent damage
- Don't hang masks by the straps — distorts the shape
Inspection schedule
| Item | Frequency |
|---|---|
| User pre-use check | Every time before donning |
| Visual inspection | Weekly (or before each use) |
| Detailed inspection | Monthly |
| Thorough examination | As per manufacturer guidance |
Records to maintain
Keep records of:
- Fit testing results (who, when, what RPE, result)
- Training provided
- Maintenance and inspection activities
- Equipment issued to individuals
Common mistakes
These errors undermine RPE protection — sometimes with fatal consequences.
Mistake 1: Using RPE as the first choice RPE should be the last line of defence, not the first. If you reach for masks before considering extraction or substitution, you're doing it backwards.
Mistake 2: One size fits all Different people have different face shapes. A mask that fits one person may leak badly on another. Individual fit testing is essential.
Mistake 3: Ignoring facial hair Stubble that can be felt with the hand is enough to break the seal. Workers must be clean-shaven in the seal area, or you must provide loose-fitting alternatives.
Mistake 4: Reusing disposable masks Disposable masks are designed for single use. Storing them in a pocket and reusing them degrades performance and introduces contamination.
Mistake 5: Wrong filter for the hazard A dust filter won't protect against solvent vapour. A solvent filter won't protect against ammonia. Match the filter to the specific hazard present.
Mistake 6: Skipping the user seal check Even a properly fit-tested mask can leak if put on incorrectly. User seal checks take seconds and should happen every time.
Mistake 7: Wearing RPE in oxygen-deficient atmospheres Filtering RPE cleans the air — it doesn't add oxygen. In oxygen-deficient atmospheres (below 19.5%), only breathing apparatus will protect you.
Mistake 8: No maintenance programme Reusable RPE needs regular cleaning, inspection, and part replacement. Without a programme, equipment degrades and protection drops.
Frequently asked questions
HSG53 itself is guidance, not law. However, following it helps you comply with legal requirements under COSHH, the PPE Regulations, and the Health and Safety at Work Act. The HSE can use HSG53 as a benchmark for what reasonably practicable protection looks like.
Yes. All tight-fitting RPE must be fit tested, including disposable FFP masks. The mask must fit the individual wearer's face. Qualitative fit testing is acceptable for FFP masks.
HSE recommends fit testing every 1-3 years, plus whenever the RPE model changes, or the wearer's face changes significantly (weight loss/gain, dental work, facial scarring). Some high-risk industries test annually.
Workers with facial hair that passes under the seal of a tight-fitting mask cannot achieve adequate protection. Options include: keeping clean-shaven in the seal area, or using loose-fitting RPE such as powered hoods or airline helmets that don't rely on a face seal.
FFP2 filters at least 94% of particles and has an assigned protection factor of 10. FFP3 filters at least 99% and has a protection factor of 20. Use FFP3 for higher hazards including carcinogens, biological agents, and situations where higher protection is needed.
For particle filters: when breathing becomes noticeably more difficult. For gas filters: when you detect breakthrough (smell the contaminant). Always follow manufacturer guidance on maximum service life and never exceed filter expiry dates.
Fit testing should be conducted by a competent person trained in the specific method used. Many organisations train in-house staff; others use external fit testing providers. The tester should understand the equipment, the testing method, and be able to interpret results.
It depends on the atmosphere. Filtering RPE can only be used if there's adequate oxygen (at least 19.5%) and the hazard can be filtered. In oxygen-deficient, IDLH, or unknown atmospheres, only breathing apparatus should be used. Confined space entry has additional requirements beyond RPE.
Keep records of: fit testing (who, when, what equipment, result), training provided, maintenance activities, equipment issued, and any incidents or failures. There's no specified retention period but 3-5 years is sensible, or longer for health surveillance purposes.
No. A fit test is a formal assessment that verifies a specific make and model of RPE fits an individual. A user seal check is a quick check performed every time the mask is put on to verify it's properly donned. Both are necessary — fit testing confirms the right equipment; seal checks confirm proper use.
RPE programme management
Effective RPE protection requires more than just buying equipment. A managed programme should include:
- Hazard assessment — Identify where RPE is needed
- Equipment selection — Choose appropriate RPE for each hazard
- Fit testing — Test each wearer with their assigned RPE
- Training — Ensure workers know how to use, check, and care for RPE
- Maintenance — Clean, inspect, and replace equipment
- Supervision — Check RPE is being used correctly
- Review — Regularly evaluate programme effectiveness
Assign someone competent to manage the programme and ensure they have the time, resources, and authority to do it properly.
Next steps
Learn about hazardous substances and COSHH:
Understand personal protective equipment more broadly:
Need help with respiratory protection? A health and safety consultant can assess your workplace exposures, help select appropriate RPE, establish a fit testing programme, and train your staff on correct use.
Related articles:
HSE guidance documents:
- HSG53 — Respiratory protective equipment at work — Full guidance document
- INDG479 — Respiratory protective equipment (RPE) and you — Worker leaflet
- INDG291 — Selecting respiratory protective equipment — Selection overview
Useful resources:
- HSE RPE topic page — Official HSE guidance
- Fit Testing Fit2Fit — Fit test provider accreditation scheme
- BSIF RPE guidance — British Safety Industry Federation
Disclaimer: This guide provides general information about HSG53 and respiratory protective equipment. It does not constitute legal advice. RPE selection depends on specific hazard assessments and workplace conditions. For complex respiratory hazards or high-risk environments, consult a qualified occupational hygienist or health and safety professional.