P1 vs P2 vs P3: why & when to replace your respirator particulate filters

P1 vs P2 vs P3: why & when to replace your respirator particulate filters

Air-Purifying Respirators Explained (APR) Reading P1 vs P2 vs P3: why & when to replace your respirator particulate filters 7 minutes Next General Respiratory Protection Guidance for Employers and Workers

Respirators are used to protect wearer from harmful dust, fumes, vapors, mist, and gases. To get maximum protection from respirator you need to get right filters on them and you should wear it with proper seal around your face. If you don’t get right filters on your respirators then it won’t save you from hazards that they are not designed for.

To help you with right selection of filters, these filters are divided into different ratings based on the levels of protection they offer and type of environment they are suitable for. Each of these filters is rated according to their APF (Assumed protection factor and OEL (occupational Exposure Limit).

You will find many filters with different ratings but among those P1, P2, and P3 ratings are very popular and are rated highest among all.

You must remember that these filters are very important while choosing them for your different work and industries like construction, agriculture, pharmaceutical, and even for your DIY projects at home. Always remember that they offer different levels of protection and that is why it is very important you find the correct level of protection you need from a respirator.

Types of Respiratory Hazards

NIOSH classifies contaminated air into the following categories:


1. Dust/Fibers: -

These are the particles that are generated by means such as grinding, cutting, and sanding.

2. Examples are: -

Calcium carbonate, cement (silica) dust, sulphur, coal, clay, ferrous metals (steel, stainless steel, cast iron), wood dust and asbestos.

3. Mists: -

These are the airborne droplets of liquid usually formed by condensation of vapor or by splashing and spraying.

4. Examples are:-

Oil mists, acid mists, condensation of water vapour to form fog and paint mist.

5. Fumes:-

These fumes are very fine particles. They are usually less than 1.0pm in diameter, formed from a volatilized solid that has condensed in cool air. You will find these fumes with molten metal while doing welding, soldering etc.

6. Examples are: -

Welding, soldering and bushfire smoke.

Gases: - Gases are those formless fluids that expand freely and occupy the space in which they are confined.

Examples are:- Carbon monoxide, carbon dioxide, Acid gas and vapor like sulfur dioxide.

Vapor:- Vapors are gas form of a substance but these are in the form of a solid or liquid when at room temperature and pressure.

Examples are: - Mercury vapors, organic vapors, inorganic vapors, methylene chloride, toluene and mineral spirits.

What types of filters are there?

Usually there are three types of filters.

Particulate filters: - These are the filters that give protection against dust, mists and fumes. They also protect against respirator hazards in the workplace where smoke, mould, bacteria etc. are present.

Gas and vapour cartridges filters:- There are gas and vapor cartridges filters available that protect wear from gases and vapors only. Furthermore there are different kinds of gas and vapor cartridge filters for different kinds of gases.

Combination filters:- These combination filters protect against both particles as well as gases. There are different kinds of combination particulate/cartridge filters available that are used depending on the gas or vapour present in the air.

What’s a P1? P2? P3?

What does a P1 filter protect against?

1. P1 – Filters about 80% of particles smaller than 2 micrometers

2. P1 protects against low levels of dust particles.

3. They also protect against solid and liquid aerosols.

4. These P1 filters can be used for hand sanding, drilling, and cutting.

5. OEL: Protects against materials in concentrations 4x limit.

6. APF: Protects against materials in concentrations 4x limit.

Use of P1 filters: - You can use these filters for mechanically generated particles. Examples are particles formed by crushing, grinding, drilling, sanding, cutting etc including wood dust and silica.

What does a P2 filter protect against?

1. P2 – Filters about 95% of particles smaller than 0,5 micrometer

2. These P2 filters are better than P1 and they give protection against moderate levels of dust.

3. P2 filters are best in protection against solid and liquid aerosols.

4. You can use these filters for protection when working with plastering and sanding.

5. OEL: Protects against materials in concentrations 12x

6. APF: Protects against materials in concentrations 10x limit.

Use of P2 filters:- These P2 filters are best for use with mechanically and thermally generated particles. Examples are welding fumes; soldering fumes, bushfire smoke, and even where P1 filters are used. These filters are also used for protection against contagious viruses like TB, SARS, and COVID-19/CORONA VIRUS.

What does a P3 filter protect against?

1. P3 – Filters about 99,95% of particles smaller than 0,5 micrometer

2. P3 filters are rated highest among P1 and P2 filters

3. They protect wearer from higher levels of dust

4. They give protection against solid and liquid aerosols.

5. These can be used in pharmaceutical industries, chemical industries, pesticides, and where level of hazard is high.

6. They can be used as an asbestos mask.

7. OEL: Protects against materials in concentrations 50x limit.

8. APF: Protects against materials in concentrations 20x limit.

9. These filters are best when you need protection against virus and bacterial infection. You can use these filters on your respirtaor when if you need protection against COVID-19/ CORONA VIRUS.

Use of P3 filters:- These P3 filters provides higher protection as compared to P1 and P2 filters. These filters have highest efficiency particle filter class and are used for particulates that are of high toxicity or at high concentrations. Examples are protection against pesticides fumes/gases, and you can use them in the workshop for wood dust, painting, blowing in attic insulation, or cleaning out the dusty old attic, these filters will protect your lungs. P3 filters are to protect against highly toxic or irritant particles.

How long particulate do filters last?

Usually you should change your filters after 40 hours of use. You can also change them when it gets tough to breathe through them. Whenever you find tough to breathe, you should change the filters immediately.

More dusty the job work is, more quickly you have to replace them. The life of filters is five years from manufacture date but once opened maximum use time is 6 months and/or when they get damaged.

Why to replace filters?

Filters must be replaced after certain period of time because wearer won’t get desired protection from hem if they are used after 40 hours. After certain period filters get clogged up and it becomes very hard to breathe through them. Gas and vapour cartridge filters start to let contaminant through once their sorbents become saturated. This is called breakthrough.

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Maintenance of filters

1. You should replace the filters when they are damaged.

2. Never wash the filters or use any liquid to clean them.

3. Do not attempt to repair, replace any damaged filter.

4. Store the filters in a clean, dry place and away from dust.

5. To avoid deterioration store filters in an airtight container.

6. Always replace them after 40 hours of use.

7. Use them within 6 months after opening the pack.


After all the above discussion, it is clear that P3 filters are better than P1 and P2 filters. If compared with N95 mask, P2 and P3 offers higher protection and they can be used where higher protection is needed. So whenever you need to choose a filter, always go for the one that gives you higher safety and choose the one that is designed for specific task. 

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