Does a P3 filter mean a respirator is TH3?

No. P3 describes the filter's efficiency, while TH3 describes the certified performance of the complete powered respirator. A device can use a P3 filter and still only be certified to TH2, because the TH rating depends on the whole system (blower, airflow, hose, headtop and filter) tested together, not the filter alone.

What is the difference between TH2 and TH3?

TH2 has an Assigned Protection Factor (APF) of 20 and TH3 has an APF of 40, so TH3 provides twice the protection of TH2 under EN 12941. TH2 is appropriate where a COSHH risk assessment shows exposure falls within its range. Many organisations choose TH3 for the extra headroom and flexibility across varied tasks.

What is the APF of a TH3 respirator?

A TH3 powered respirator has an Assigned Protection Factor (APF) of 40, meaning it is designed to be used in atmospheres up to 40 times the Workplace Exposure Limit, subject to a suitable risk assessment.

Is TH3 always the right choice?

Not automatically. The correct level of respiratory protection should always be determined by a suitable COSHH risk assessment. TH3 offers the highest certified protection under EN 12941, but a lower rating may be appropriate depending on the contaminant, concentration and task.

Do you need a face fit test for a TH3 powered respirator?

Loose-fitting powered respirators, including TH3 devices like the AirMask 1000, do not require face fit testing because they do not rely on a tight seal against the skin. This is different from tight-fitting masks (disposable, half and full-face), which legally require a face fit test for each wearer under HSE guidance.

What Does TH3 Mean? A Guide to Powered Respirator Protection

Cires-Safe
Jun 16
3 min read

Updated: Jun 25

Powered respirator ratings confuse a lot of people. Two devices can use a similar filter and still offer very different levels of protection. This guide explains the differences between TH1, TH2 and TH3 system in plain English, so you can choose the right respirator with confidence.

Firstly, what is a “TH” rating?

TH ratings show how much contaminated air is allowed to leak into a powered loose-fitting respirator. If there were 10,000 particles outside, a TH1 respirator could allow up to 1,000 inside, TH2 up to 200, and TH3 up to just 20. The higher the TH number, the lower the inward leakage, and therefore the higher the protection.

Classification	Assigned Protection Factor (APF)
TH1	10
TH2	20
TH3	40

*Subject to risk assessment and manufacturer instructions.

In short, TH3 gives twice the protection of TH2, and four times that of TH1.

Higher TH rating = higher certified protection.

No face fit testing. Beard friendly.

Loose-fitting powered respirators do not rely on a tight seal against the face, so they do not need face fit testing and can be worn with beards or stubble.

Disposable masks and non-powered negative-pressure half or full-face masks work differently. They rely on a tight face seal, so when the wearer breathes in, air is pulled through the filter. If facial hair breaks that seal, contaminated air can be drawn in around the edges.

That is why many organisations choose loose-fitting powered respirators: no face fit testing, no clean-shaven requirement, and one practical solution for the whole team.

Common Filter Misconceptions:

A loose-fitting powered respirator does not automatically give more protection than an FFP2 or FFP3 disposable mask.

Always check two things: the TH rating, which shows system leakage, and the P rating, which shows filter efficiency.

Many TH2 powered respirators use P2 filters, which may not be suitable for silica dust, construction dust, stone dust or other hazardous dusts. For higher-risk dust work, look for TH3 with a P3 filter.

Why organisations choose loose-fitting protection

Many organisations choose loose-fitting powered respirators because they are simpler to manage across a workforce.

No face fit testing to arrange, pass or repeat.
Works with beards and stubble, with no clean-shaven requirement.
One practical solution for different people, tasks and departments.
Less compliance risk, especially where staff struggle to pass a fit test.
Higher protection options, when certified to TH3 with a P3 filter.

Where this lands in practice

TH1Basic protection for very low-risk or domestic-type use.

TH2For lower-dust workplaces where the risk assessment confirms this level is enough.

TH3Industrial-grade protection for higher-risk dust, healthcare, laboratory, manufacturing and construction environments.

Important: Always check the filter requirement as well. The TH rating shows system leakage; the filter rating shows what the respirator can filter.

Where this lands in practice

Different ratings suit different environments. Typical use cases include:

TH1: light industrial work, general maintenance, lower-dust environments.
TH2: manufacturing, engineering, warehousing and general industrial processing where exposure exceeds TH1 capability but stays within TH2 limits.
TH3: healthcare, pharmaceutical manufacturing, laboratories, construction, waste and recycling, heavy industry, metalworking, mining, food manufacturing and dust-intensive processes.

The Key Takeaways:

TH3 should be the benchmark for workplace respiratory protection.

TH rating measures the complete respirator system, not just the filter.

Under EN 12941, TH3 is the highest protection level. It provides an APF of 40, compared with 20 for TH2 and 10 for TH1.

Loose-fitting PAPRs also remove the need for face fit testing and can be worn with beards or stubble.

Choose a respirator by its TH rating, filter rating and risk assessment – not by the filter alone.

The takeaway

TH rating measures the whole respirator, not the filter.
TH3 is the highest level under EN 12941, twice the protection of TH2, 4 times the protection of TH1.
Loose-fitting PAPRs need no fit test and work with beards.
Choose by TH rating and your risk assessment, not by the filter.

Reviewing your respiratory protection programme?

CIRES supplies the AirMask 1000, a TH3 PAPR respirator delivering the highest certified level of protection available under EN 12941, in both full-face and half-mask configurations, so your team gets maximum certified protection with a choice of fit. If you want help mapping the right TH rating to your risk assessment, our team is happy to talk it through with no obligation.

Get in Touch

Yes. Because loose-fitting powered respirators do not seal against the face, they can be worn with beards, stubble and other facial hair. Tight-fitting masks cannot, because facial hair breaks the seal they depend on, so a loose-fitting powered respirator is often the only effective option for workers with beards.