Photo credit: 3M
This question comes up frequently, and while it might seem straightforward, it's quite nuanced.
The brief answer to which respirator is best—reusable or disposable—is: it depends.
This article explores protection factors and compares the pros and cons of half-face reusable and disposable filtering facepiece respirators. We'll help you understand why one is not necessarily better or worse than the other.
We will concentrate on half-face reusable respirators and filtering facepiece respirators (at the P2/N95 filtration level) as these are the types most commonly compared when folks ask which is better.
First, a brief overview of each type of mask.
Reusable (Elastomeric) Respirators
Reusable respirators - also called elastomerics - are ones like you see in the photo below. You can attach various types of particulate filters and/or gas & vapour cartridges on the mask.
When a P2 or N95 particulate filter is attached to an elastomeric mask, the filtration level is effectively the same as a disposable filtering facepiece P2 or N95 mask.
Just so you know, you can attach P3 filters to a reusable respirator, but the protection level is still considered P2. This is an Australian standard.
Disposable Filtering Facepiece Respirators
Filtering facepiece respirators (FFRs) are like the ones you see in the photo below. The filtration level is the same as when you attach a P2 or N95 filter to a reusable respirator.
Filtering facepiece respirators are generally used for short-term work or projects whereas resusable ones are more appropriate for long-term use.
The definitions of 'short term' and 'long term' vary greatly depending on who you ask.
Protection Factors
Let’s talk about protection factors.
Grasping the concept of protection factors will help clarify why disposable and reusable masks may not necessarily be better or worse than each other.
Protection factors are measurements that indicate how well a respirator is expected to protect the wearer from airborne contaminants.
There are three main types of protection factors to understand: fit factors (FF), assigned protection factors (APF), and workplace protection factors (WPF).
Fit Factor
A fit factor is a numerical value that represents the effectiveness of a respirator's seal on the wearer's face. Fit factors are calculated during quantitative fit testing.
In this article, when we mention quantitative testing and fit factors, we're referring to the CNC (condensation nuclei counting) method typically performed with AccuFit or PortaCount fit test machines.
Fit factors quantify the level of protection provided by the respirator by comparing the concentration of ambient particles outside the respirator to the concentration of particles detected inside the respirator.
Different countries and fit testing standards have different pass levels.
In Australia:
Disposable filtering facepiece respirators (commonly called N95s and P2s) require a fit factor of 100 to pass a fit test.
Half-face reusable respirators also require a fit factor of at least 100 to pass a fit test.
Full-face respirators require a fit factor of at least 500 to pass a fit test.
With disposable masks, the highest fit factor that can be calculated on a fit test machine is 200+. Half-face reusable respirators can potentially achieve fit factors in the thousands.
If this is the case, half-face reusable respirators with high fit factors (well over 200) must be better than disposable filtering facepiece masks, right?
Not necessarily. This brings us to the topic of assigned protection factors (APF).
Assigned Protection Factors
An assigned protection factor is generally considered more important than a fit factor because it provides a practical measure of the overall level of protection that a respirator is expected to offer in a real-world setting (on trained, fit tested and clean-shaven people).
The fit factor, on the other hand, measures how well a specific respirator fits an individual at the time of fit testing.
Different countries have different APF values. In Australia, the AS/NZS 1715:2009 specifies the APFs of 10, 50, 100 and 100+.
APF 10: the respirator is expected to reduce the concentration of airborne contaminants by a factor of 10 when used correctly.
APF 50: the respirator is expected to reduce the concentration of airborne contaminants by a factor of 50 when used correctly.
APF 100: the respirator is expected to reduce the concentration of airborne contaminants by a factor of 100 when used correctly.
Here's a chart outlining the APFs and different mask/filter combinations:
Adapted from the AS/NZS 1715: 2009
For filtering facepiece respirators and half-face reusable respirators, the maximum APF is 10. You can't assign an APF higher than this for these two types of respirators.
This means that even if a reusable half-face respirator achieves a higher fit factor than a disposable filtering facepiece respirator, the APF is the same - up to 10.
In case you were wondering, to determine the minimum APF you would use this calculation:
Airborne Contaminant Concentration Level (based on air monitoring) / Workplace Exposure Standard = Minimum APF
Example:
Airborne levels of respirable crystalline silica in a workplace were calculated to be 0.10mg/m3. The WES is 0.020mg/m3.
0.10 / 0.020 = 5
An APF of 'up to 10' would be appropriate based on this calculation and we could use a disposable filtering facepiece P2 or a reusable half-face respirator with P2 filters.
If we arrived at the number 12 instead of 5, we'd move to 'up to 50' APF. In this instance, we'd need at a minimum a full face respirator with a P2 filter.
Capeesh?
Workplace Protection Factors
The workplace protection factor is a measure used to evaluate the performance of RPE in real-world workplace conditions. It reflects the level of protection that a respirator provides to workers by comparing the concentration of contaminants in outside air to the concentration of particles inside the respirator while it is being used in the workplace.
In Australia, the WPF is determined through workplace studies where the actual performance of the RPE is assessed in the specific environment where it will be used.
The WPF considers various factors including the type of respirator, the fit of the respirator, the nature of the work being performed, and the environmental conditions.
Overall, the WPF provides a more practical and realistic understanding of how well a respirator protects its wearer in everyday use.
While you won't be the one calculating WPFs, we believe it's worth knowing about.
Fit Factors as They Relate to Assigned Protection Factors
Still with us? Now we'll tell you how fit factors relate to assigned protection factors.
A generally accepted practice is to use ten times the APF as the required fit factor pass level during quantitative fit testing.
For example, if you've determined (based on the level of contaminant in your workplace and workplace exposure standards) that an APF of 10 is the minimum requirement for your RPE, you would calculate APF of 10 x 10 = 100. A fit factor of at least 100 should be achieved during a quantitative fit test.
If an APF of 50 is required, 50 x 10 = 500, so a fit factor of at least 500 would be required. And an APF of 100 would require a fit factor of at least 1000.
The thinking behind this is if you can achieve a fit factor higher than the APF, then you can be reasonably optimistic about achieving that APF in the actual workplace (when the respirator is worn correctly, fit tested, and the person wearing it is trained).
A safety factor is used to recognise the fact that the fit test, and resulting fit factor, are only a simulation of the workplace.
Now let's say you get a fit factor of 5,383 on a reusable half-face respirator. Wouldn't that increase the APF?
No. And here's why.
Standardisation and Safety Margins: The APF is a conservative value that considers variations in fit, user behaviour, and other real-world factors. Even though a very high fit factor (like 5,383) indicates a great fit, it doesn't change the APF.
Regulatory Limits: The APF is set by regulatory bodies. One can't change the APF based on individual fit test results and fit factors.
In other words, if an APF of 10 is required, achieving a fit factor of at least 100 during a fit test shows that the respirator (when used correctly) likely provides enough protection to meet the required minimum APF. The same concept applies for APFs of 50 and 100.
And remember, for reusable half-face respirators and disposable FFRs, the minimum fit factor is 100 and the highest APF you can assign is 10.
There’s no need to aim for an excessively high fit factor if it already exceeds the necessary APF (when multiplying the APF by 10).
Make sense?
Disposable vs Reusable: Pros and Cons
Now that we know how protection factors work, let's look at the pros and cons of disposable vs reusable respirators.
This chart sums it up nicely:
If you've determined the APF you need for your RPE is 'up to 10' (and no higher than 10), then disposable filtering facepieces and half-face respirators are both appropriate choices filtrationally speaking (a made up word there, filtrationally).
You'll need to determine, based on your workplace, tasks, exposure times, wear times, user comfort, temperature/humidity, risk assessments etc. which respirator is most suitable.
For example, if staff are required to wear P2 level of protection for a couple of hours a day, then disposable P2 masks may be the best option.
If they need to use respirators for many hours a day, then a reusable mask may be more appropriate.
Also, consider comfort and likelihood of use for each type of mask. If you have staff that are more likely to be compliant with using disposable respirators, this may factor into your decision. And vice versa.
Keep in mind that some projects and worksites will have rules around which type of respirators they require onsite. For example, we know that some projects do not allow disposable masks where respirable crystalline silica is the hazard. Know the requirements before you spend any dough on RPE and fit testing.
No matter which respirators you choose, it's imperative that staff are properly trained in how to use them safely and appropriately and that the masks have been fit tested to ensure they're providing their stated level of protection.
Wrapping Up
Well, that was a more detailed response than you were probably anticipating! But it's crucial to understand how to properly select any RPE to ensure you and your staff are safe at work.
To sum up:
Knowing the required assigned protection factor - based on your workplace airborne contaminants and WES - is imperative to determine what type of respirator and filters you need (filtering facepiece, half-face or full-face).
Although reusable respirators can typically achieve higher fit factors than disposable filtering facepiece masks, the APF is the more important factor when choosing RPE.
Higher fit factors achieved on reusable half-face respirators do not change the APF. The APF for reusable and disposable respirators is 10. And the minimum passing fit factor for both is 100.
Because the filtration level between half-face reusable respirators and filtering facepiece masks is essentially the same, choose your RPE based on workplace risk assessments, wear time, work tasks, user preference, site requirements, etc.
Consider the pros and cons of each, and specific worksite rules, when making your selection.
Involve employees when making decisions about health and safety in your workplace.
There really is a lot of know when it comes to respiratory protective equipment. At Fit Test Victoria, we offer Respiratory Protective Equipment Courses tailored to your workplace and employees.
Call us at 0488 688 454 or email info@fittestvic.com.au to learn more.
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