How do you read a respirator cartridge label?

Short answer: To read a respirator cartridge label, check four things: the ANSI/ISEA 110 color band that names the hazard class (black for organic vapor, white for acid gas, magenta for P100 particulate), the gas/vapor letter designation such as OV, AG, or P100, the NIOSH TC approval number that proves it is certified for that exact respirator, and any end-of-service-life indicator (ESLI) or expiration date. The label also lists the manufacturer and model so you can confirm the cartridge actually fits your facepiece.

How to read a respirator cartridge label and color code (2026)

Knowing how to read a respirator cartridge label is what stops you from bolting the wrong protection onto an otherwise perfect mask, because the label is the only place that tells you the hazard class, the certification, and the expiration in one spot. The color-band system is set by ANSI/ISEA 110, and the certification itself comes from NIOSH under 42 CFR Part 84. This guide is written for workers and safety managers who need to read a cartridge label at the bench and trust what they put on their face.

Below we decode each element of the label - the ANSI/ISEA 110 color band, the gas and vapor letter designations such as OV and AG, the particulate class like P100, the NIOSH TC approval number, and the end-of-service-life indicator or expiration date. We then walk through a real cartridge label so the workflow is concrete, and connect it to choosing the right cartridge in the first place.

Why this matters.
Reading the label wrong means breathing a hazard the cartridge was never built to stop, or trusting a cartridge that is expired or uncertified for your mask. OSHA 1910.134(d) requires that respirator components be NIOSH certified and selected for the specific contaminant - and the NIOSH TC number printed on the label is your proof of that certification. A black OV band on a cartridge facing an acid gas, or an expired P100 filter, leaves the wearer effectively unprotected even though the mask seals perfectly.

Part 1 - What it takes to read a respirator cartridge label

A respirator cartridge or filter label packs four kinds of information into a small space:

• Hazard class - shown by a color band and a letter designation (the contaminant it filters).
• Certification - the NIOSH TC approval number that proves it is approved for use with a specific respirator.
• Service life cues - an end-of-service-life indicator (ESLI) where one exists, plus an expiration or use-by date.
• Identity - the manufacturer and model, so you can confirm the cartridge fits your facepiece.

Reading all four prevents the two classic errors: wrong hazard class, and a cartridge that is either expired or not certified for your mask. Choosing among classes is covered in our companion guide on how to choose a respirator cartridge.

Part 2 - The ANSI/ISEA 110 color bands

The colored band around a cartridge is standardized by ANSI/ISEA 110 so that the same color means the same hazard across every brand. The core colors you will see most often:

• Black = organic vapor (OV)
• White = acid gas (AG)
• Green = ammonia and methylamine
• Magenta = P100 particulate (HEPA-class)
• Yellow = combination organic vapor / acid gas

A cartridge that combines a gas/vapor media with a particulate filter carries two bands - for example a black OV band plus a magenta P100 band on an OV/P100 combination cartridge. For the full color key, see our dedicated cartridge color codes reference; on the physical label, match the band to the hazard you confirmed in your exposure assessment.

Part 3 - The letter designations: OV, AG, P100 and more

Alongside the color band, the label prints letter and number designations that name the protection precisely:

• OV - organic vapor (solvents, paints, fuels)
• AG - acid gas (chlorine, sulfur dioxide, hydrogen chloride)
• OV/AG - combination organic vapor and acid gas
• P100, P95, N95, R95 - particulate filter class (the letter is oil resistance, the number is efficiency)
• HF - hydrogen fluoride, often paired with acid gas

For particulate filters, the letter tells you oil resistance - N (not oil resistant), R (oil resistant up to 8 hours), P (oil proof) - and the number is filtration efficiency: 95, 99, or 100 (99.97 percent). So a magenta P100 band such as on the 3M 2091 P100 filter means oil-proof, 99.97 percent particulate capture. The efficiency classes are compared in N95 vs P100.

Part 4 - The NIOSH TC approval number

The most important line on the label for compliance is the NIOSH approval number, formatted as TC-##X-#### (for example TC-23C-2345). This number proves the cartridge is certified under 42 CFR Part 84 and - critically - that it is approved for use with a specific respirator facepiece. NIOSH certifies the cartridge and the mask together as an approved combination, not separately.

• The TC prefix and middle code indicate the approval and device class.
• You can verify any TC number against the NIOSH Certified Equipment List.
• A cartridge with no TC number, or used on a mask outside its approval, is not NIOSH approved for that use - which fails OSHA 1910.134(d).

Always confirm the TC number on the label matches an approval that includes your facepiece. Cartridges are not universally interchangeable across brands; the certification is what binds them. For how the certification system works, see our NIOSH 42 CFR Part 84 guide.

Part 5 - ESLI and expiration markings

Two parts of the label tell you when the cartridge is finished:

• End-of-service-life indicator (ESLI): some gas and vapor cartridges have a passive ESLI - a color-changing window or strip that signals when the sorbent is becoming saturated. Where an ESLI is not present (the majority of OV cartridges), you cannot rely on smell or taste and must use a change-out schedule instead.
• Use-by / expiration date: printed on the cartridge or its packaging. After this date the sorbent and seals are no longer guaranteed, even if the cartridge was never opened.

Because most OV cartridges have no ESLI, OSHA requires a documented change-out schedule based on your exposure - explained in our change-out schedule guide. Storage matters too: an unopened cartridge still ages, so check the shelf life and storage rules before you trust the date.

Part 6 - Confirming the cartridge fits your respirator

The last thing the label tells you is identity - the manufacturer and model - which you use to confirm the cartridge actually mounts on your mask. Connection systems are brand- and series-specific:

• 3M bayonet cartridges (6000-series media and 2000-series filters) fit 3M 6000, 6500, and 7500 half masks and 6000/7800 full facepieces.
• 3M Secure Click cartridges use a different push-to-click connection and fit only HF-800 and FF-800 masks.
• Honeywell North and MSA use their own bayonet systems.

A label that reads OV/P100 with a valid TC number is still wrong if it does not mount on your facepiece. Match the model on the label to the connection on your mask, using brand selection hubs like our 3M filter and cartridge guide and Honeywell North cartridge guide. Then verify the install with a user seal check.

Reading a respirator cartridge label: color bands and designations (ANSI/ISEA 110)

Part 7 - Worked example: read a respirator cartridge label (3M 60921)

Here is how to read a respirator cartridge label using a combination cartridge such as the 3M 60921 OV/P100 cartridge, intended for a 3M bayonet half mask like the 3M 7500 Series.

1. Read the color bands. The 60921 shows a black band (organic vapor) plus a magenta band (P100 particulate). Two bands mean a combination cartridge - here OV gas/vapor media bonded to a P100 particulate filter.
2. Read the letter designation. Confirm the printed designation matches: OV/P100. P means oil-proof and 100 means 99.97 percent particulate efficiency, so this cartridge handles solvent vapors and fine oil-bearing particulates together.
3. Match the hazard to your assessment. Verify OV/P100 is what your exposure assessment calls for - organic vapor plus particulate, below the cartridge's concentration limits and not an immediately dangerous (IDLH) atmosphere, which requires supplied air instead.
4. Verify the NIOSH TC number. Find the TC-##X-#### approval number on the label and confirm it lists your 3M bayonet facepiece as an approved combination. No TC number, or a mask outside the approval, means it is not NIOSH approved for your use.
5. Check the date and any ESLI. Read the use-by date on the cartridge or packaging. The 60921 has no passive ESLI for the OV media, so plan a documented change-out schedule rather than relying on smell.
6. Confirm the connection fits. Read the manufacturer and model to confirm it is the 3M bayonet system, then mount both cartridges, twist to lock, and run a user seal check before entering the hazard.

The same label-reading routine applies whether you are holding a single-media 3M 6001 OV cartridge, a multi-gas 3M 60926 multi-gas/P100 cartridge, or another brand entirely. To pick the right class before you read the label, see how to choose a respirator cartridge and the full color code reference.

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Frequently asked questions

How do you read a respirator cartridge label?

Read four elements: the ANSI/ISEA 110 color band and letter designation (the hazard class), the NIOSH TC approval number (the certification, which must include your mask), the ESLI or expiration date (when to discard), and the manufacturer and model (so it fits your facepiece). All four must check out before you trust the cartridge - see our color code reference.

What do the colors on a respirator cartridge mean?

The color band is set by ANSI/ISEA 110 so it means the same hazard across brands: black is organic vapor, white is acid gas, green is ammonia/methylamine, and magenta is P100 particulate. Combination cartridges carry two bands. The full key is in our cartridge color codes guide.

What is the NIOSH TC number on a cartridge label?

It is the NIOSH approval number, formatted TC-##X-####, that proves the cartridge is certified under 42 CFR Part 84 for use with a specific respirator. NIOSH approves the cartridge and mask together, so the TC number must list your facepiece. Verify it on the NIOSH Certified Equipment List - background in our 42 CFR Part 84 guide.

What does P100 mean on a cartridge label?

P means oil-proof (effective against oil-based and non-oil particulates) and 100 means 99.97 percent filtration efficiency - the same efficiency as HEPA. The magenta band signals P100. It is the highest particulate class; see how it compares in N95 vs P100.

What is OV on a respirator cartridge?

OV stands for organic vapor - solvents, paints, fuels, and similar carbon-based vapors. It is marked with a black ANSI/ISEA 110 band, as on the 3M 6001 OV cartridge. OV cartridges absorb vapor onto activated carbon and have a finite service life that requires a change-out schedule.

What does an ESLI on a cartridge do?

An end-of-service-life indicator is a passive color-changing window or strip on some gas/vapor cartridges that signals when the sorbent is nearing saturation. Most organic vapor cartridges do not have one, so you cannot rely on smell - you must use a documented change-out schedule instead.

Do respirator cartridges have an expiration date?

Yes. A use-by or expiration date is printed on the cartridge or its packaging; after it, the sorbent and seals are no longer guaranteed even if the cartridge is sealed. Storage conditions also age cartridges - see cartridge shelf life and storage.

What does a green band on a cartridge mean?

Green indicates ammonia and methylamine protection, such as the 3M 6004 ammonia/methylamine cartridge. Ammonia is a specific gas that ordinary organic vapor cartridges do not stop, which is exactly why the color code calls it out separately.

Why does my cartridge label have two colors?

Two color bands mean a combination cartridge that protects against more than one hazard class - for example a black OV band plus a magenta P100 band on an OV/P100 cartridge, or a yellow OV/AG band plus magenta on an 3M 60923 OV/AG/P100. Each band corresponds to one protection it provides.

How do I know if a cartridge fits my respirator?

Read the manufacturer and model on the label and match the connection system to your mask - 3M bayonet, 3M Secure Click, Honeywell North, and MSA are not interchangeable. The NIOSH TC number must also list your facepiece. Brand hubs like our 3M cartridge guide map cartridges to masks.

What is the difference between N, R, and P on a filter label?

The letter is oil resistance: N filters are not resistant to oil, R filters resist oil for up to 8 hours, and P filters are oil-proof. The number after it - 95, 99, or 100 - is filtration efficiency. So P100 is oil-proof at 99.97 percent, while N95 is non-oil-resistant at 95 percent. Compare classes in N95 vs P100.

Can I still read a respirator cartridge label if it is worn off?

No. If you cannot read the hazard class, TC number, or date, you cannot verify the cartridge is the right type, certified, or in date - so it must be discarded. Storing cartridges in their packaging until use, per the shelf life guide, keeps the label legible.

Does the color code apply to disposable respirators too?

The ANSI/ISEA 110 color bands are for gas and vapor cartridges and particulate filters used on reusable respirators. Disposable filtering facepieces are marked instead with their NIOSH class (N95, P100, etc.) and TC number printed on the mask. Browse them in disposable respirators.

Is the cartridge color code required by OSHA?

The color band scheme itself is the ANSI/ISEA 110 consensus standard, but OSHA 1910.134(d) requires that you select NIOSH-certified cartridges appropriate to the contaminant - and the label color and TC number are how you confirm both. See the standard explained in our OSHA 1910.134 guide.

What does a magenta band mean on a respirator filter?

Magenta (a purple-pink) is the ANSI/ISEA 110 color for P100 particulate filters - oil-proof, 99.97 percent efficiency. A magenta-only band, as on the 3M 2091 P100 filter, means particulate-only protection; magenta paired with another color means a combination cartridge.

How often should I read a respirator cartridge label?

Every time you mount cartridges - confirm the color and designation match the hazard, the TC number fits your mask, and the date has not passed. Then verify the install with a user seal check. Because most OV cartridges lack an ESLI, also track usage against your change-out schedule.

Further reading on this site

• Respirator cartridge color codes — the complete ANSI/ISEA 110 color key for every cartridge class.
• How to choose a respirator cartridge — matching contaminant to cartridge type before you read the label.
• NIOSH 42 CFR Part 84 — how the TC approval number and certification system work.
• Cartridge change-out schedule — what to do when a cartridge has no ESLI to watch.
• Cartridge shelf life and storage — how expiration dates and storage age a sealed cartridge.
• 3M filter and cartridge guide — maps 3M cartridges and filters to compatible masks.
• Respirator filters and cartridges — the full range of OV, acid gas, multi-gas, and P100 options.
• P100 respirator filters — magenta-banded oil-proof particulate filters and cartridges.