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When Use an Airline Respirator?

When it comes to the use of an airline respirator, there seems to be a lot of confusion. Typically the thinking is, "this application seems a bit more dangerous, so maybe an airline respirator is needed."

In this article, we will give you some basic guidelines for the use of an airline respirator. We hope this will cut through some of the confusion and indecision.

Isn't an Airline Respirator for More Dangerous Situations?

The answer to this is both "yes" and "no". Let's consider a hazard that might typically be present in a confined space: hydrogen sulfide (H2S).

There is no negative pressure cartridge respirator that is approved for meaningful levels of H2S. The gas is too dangerous. In other words, you can't wear a negative pressure full face or half mask respirator with an organic vapor cartridge to protect you from H2S.

But, NIOSH states that a full face airline respirator is acceptable "for use up to the MUC" (which is 100 PPM according to NIOSH). I'll explain "MUC" further down.

However, (1) if the amount of H2S present is unknown, (2) an emergency entry is being made, or (3) the concentration exceeds the "Immediately Dangerous to Life and Health" level (IDLH), then only an SCBA is acceptable. In other words, in these three cases, an airline respirator is not acceptable.

So, airline respirators can be used for atmospheres that are too dangerous for normal half mask respirators. But this is relative. Airline respirators are not for emergency entry, atmospheres with unknown amounts of a contaminant, or those that are IDLH.

How To Determine When an Airline Respirator Is Needed

The method for determining when an airline respirator is required, inconveniently, is to know at least two things. (1) What the hazard is. (2) How much of the hazard is present. It then requires that you consult the NIOSH Chemical Hazard Guide armed with this information and look up the hazard you are facing.

Again, we will consider H2S. This is a common hazard faced in confined space entry.

According to the NIOSH guide, as long as the REL/PEL aren't exceeded, no protection is required. The REL is NIOSH's reasonable exposure limit. The PEL is OSHA's permissible exposure limit.

The NIOSH guide tells us that these levels are very low for H2S. They are 10 PPM and 20 PPM respectively. Again, this info is found in the NIOSH Chemical Guide.

The way it works is, if H2S exceeds these levels, breathing protection is required. And to repeat, for H2S, if the levels are above the REL/PEL and below the MUC (100 PPM for H2S), an airline respirator with a full face can be used--at a minimum. The NIOSH guide tells us exactly what kind of respiratory protection is required, so there is no mystery to it at all.

How do you know how much hazard is in the air?

In the case of H2S, the answer to this is relatively simple to find out. All you need is one of our 4-gas confined space monitors. These monitors will give you a PPM readout of 4-gases, including H2S.

These meters also track time weighted averages. These are important to know. Even if the hazard is below the REL/PEL and no protection is required, the amount of hazard in the air might still exceed its limit on time weight average (TWA) exposures. In such cases, respiratory protection is required. As we've seen in the case of H2S, this would be an airline respirator up until the MUC is reached.

Important Tip

In the case of H2S in a confined space, it must be noted that ventilation of the space with a confined space blower may eliminate the need for any breathing protection. This is one of the purposes of a confined space blower.

What is the MUC?

MUC stands for Maximum Use Concentration. In the case of our H2S example, the NIOSH Guide notes that the MUC for H2S is 100 PPM. This happens to be the same as the IDLH for H2S. The two, however, aren't always the same.

Here is a shot from the NIOSH guide showing that the MUC for H2S is 100 PPM.

MUC for H2S


OSHA defines MUC as follows: "...the maximum atmospheric concentration of a hazardous substance from which an employee can be expected to be protected when wearing a respirator...".

So in the case of our H2S example, the MUC, as we said earlier, is shown in the picture to be 100 PPM. Again, this is found in the NIOSH Chemical Hazard Guide. In that guide, NIOSH tells us that a full face airline respirator, represented by Sa*, can protect adequately up to the 100 PPM MUC.

The first respirator in the list is PaprS. This stands for a Powered Air Purifying Respirator. This can be used if an appropriate chemical cartridge is available. The second respirator listed, GmFS, is a full face gas mask. The third, Sa*, is as we just said, a full face airline. The last, ScbaF, is a full face self contained breathing apparatus.


So download the NIOSH Chemical Guide and you will be well on your way to understanding when an airline respirator is required. Feel free to email us any questions at We are always glad to help. Be sure to check out our selection of airline respirators.

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