HOW IMPORTANT ARE YOUR RESPIRATOR FILTERS?
There are two primary categories of respiratory protection: air-purifying respirators (APRs) and supplied air respirators (SARs). Each type offers varying levels of protection depending on its design and assigned protection factor (APF). At the core of most are the respirator filters, which busily remove contaminants from the air you breathe.
A respirator is merely the vessel that enables the filters to purify the air you breathe - filters are the centre point for most respiratory protective equipment you are using because they are the aspect that literally filters out all of the harmful contaminants you may be exposed to, ensuring you are breathing clean, quality air.
Regardless of wearing a quality respirator that has been properly fitted (fit tested), if the filters you’re using aren’t suitable for the hazard, you will still be exposing yourself to that recognised hazard and likely at risk of incurring an occupational illness.
On the same token, if you have a quality respirator that’s ‘fit for purpose’ and you have the correct filters for hazard, if the filters are full, or often referred to as ‘loaded”, and you’re still using them, again, you will be exposing yourself to the risks that the respiratory protective equipment (RPE) was designed to filter out because the filter is full and can no longer filter the airborne contamination rendering them ineffective.
How Often Should I Replace Respirator Filters?
Gas and Vapour Filters
Several factors can shorten the shelf life of gas and vapour cartridge filters.
When it comes to your filters, always refer to the manufacturer's recommendations on the shelf life once opened. There is always a ‘shelf life’ and a ‘wearer usage life’.
The shelf life refers to the filter's life span upon being opened from the packaging, wearer's usage life is when you as the wearer become aware the filter's ‘shelf life’ has been reduced through extensive use or high levels of airborne contamination and you become aware they are no longer filtering to the same standard as initial use.
Fit Test Australia recommends writing the open date on the filters as a reference point. You need to be able to reference the date you connected them to your respirator.
Because all worker's time in a hazardous environment varies and the level of contamination can also vary, there is no straightforward advice on swapping out your filters. Some gas and vapour filters will have an exact usage disclaimer while other types of filters will rely on a scheduled swap out in line with the manufacturer's recommendations stamped expiry date for replacement.
Generally, you should replace the cartridge as soon as you can detect any contaminant by taste or smell as this is a sign of breakthrough (filters have become saturated). Many gas or vapours may not be able to be detected by smell or taste so it is never recommended to rely on just breakthrough as a signal for filter changes.
Particle Filters
For particulate filters, regardless of dates or time schedules, as soon as the wearer experiences any kind of breathing resistance, this is the key indicator that the filters are now ‘spent’ aka full, and need to be replaced.
We also recommend that you replace the filter as soon as it gets damaged or soiled, to ensure that the efficacy of the filter hasn’t been compromised.
Once a filter is opened, it must be replaced within that manufacturer's recommended time frame, a guide is usually 6 months (brands may vary), even if it hasn’t been used. An open filter will continue to absorb contaminants from the environment, even when not in use. If the filter remains unopened and is stored properly, it can last up to 5 years.
Hazardous workplaces should also establish a filter change schedule to ensure regular replacements for worker health and best practices. This is in line with a Respiratory Protection Program. When changing twin filters/cartridges, always replace them as a pair, two ‘off’ for two new ones ‘on’.
Different Respirator Filters and How Often They Should Be Replaced
Particulate filters come in two different materials; electrostatic and mechanical.
Electrostatic (as is the case with many cheaper variants) respirator filters need changing daily just like a disposable P2/N95.
Mechanical particulate respirator filters become more efficient over time. Even though mechanical particulate filters improve with use, the key indicator to change them is when the wearer experiences breathing resistance. This indicates the filters are becoming full. Because all worker's time and tasks vary in hazardous environments, it is wise to schedule changes. This is when dating the filters can help the wearer track how long their filters have been in use.
We strongly recommend workers date their filters as a reference point as they are opened and attached to their respirator. This provides a reminder of when the filter was last changed and is a visual reminder of the fact it needs to be replaced.
We recommend implementing a filter change schedule when it comes to changing your respirator filters. Creating a filter change schedule involves considering several factors that impact the service life of cartridge filters. Key factors to consider include:
Type and concentration of contaminants
Temperature
Humidity
User’s work rate
Any elements that could affect the filter's shelf life
Our team at Fit Test Australia can help you plan an appropriate fit change schedule at your fit test appointment.
As far as gas and vapour filters go, best practice suggests the following process is implemented (but always follow manufacturer recommendations on appropriate filter change).
The user records the date the filter was first installed/used
When the user first smells or tastes a substance, that filter is replaced
The date of replacement is then compared against the issue date to determine how many days it was in use prior to "breakthrough"
The new filter is then used from a new updated scheduled change out, the guide is for a duration HALF of the time which that first filter was used. I.e. if the breakthrough occurred after 20 days, all future filters should be changed after 10 days. This ensures your new filter is working appropriately for its entire use-time.
Following this model, the chances of exposure are greatly reduced.
What are the Different Types of Particles and How do I Know What to Select?
We understand that it can all get a bit confusing, especially when there are so many things to consider to make sure you stay safe. Simply, there are three types of particles that filters are designed to protect against, and we recommend different mask and filter combinations depending on the particles you need protection from.
Mechanically Generated Particles ⚠️
Examples of processes which would result in the mechanical generation of particles:
• Grinding • Mixing powders
• Chipping • Blasting
• Spraying • Sanding
Some examples of mechanically generated particulates:
• Silica dust • Coal dust
• Asbestos fibres • Lead dust
• Sodium • Hydroxide mist
P1 and P2 filters protect against mechanically generated particles. Both are available as disposable masks, replaceable respiratory filters, and powered-type filters.
Thermally Generated Particles ⚠️
Examples of work processes that would thermally generate particles:
• Smelting • Welding
• Heating • Brazing
Some examples of thermally generated particulates:
• Lead fume • Zinc Oxide fume
• Chromium fume • Manganese fume
• Welding fume • Bushfire smoke
P2 filters protect against mechanically or thermally generated particles. Available as disposable masks, replaceable respiratory filters, and powered-type filters.
Gas and Vapours ⚠️
Some examples of gases and vapours:
• Carbon Monoxide (CO)
• Nitrogen Dioxide
• Phosgene
• Chlorine
• Hydrogen Sulphide (H2S)
P3 filters paired with gas & vapour filters protect against highly toxic or irritant particles. Protection against gases and vapours may be obtained by the use of air-purifying RPE or by a supplied-air device.
To achieve P3 filter classification, a full-facepiece respirator is required (for non-powered air) as covering the full face provides additional skin and eye protection, or a head covering or full-facepiece for a Powered Air Purifying Respirator (PAPR).
P3 filters are available as replaceable filter types and powered types.
Appropriate Storage of Respiratory Filters Impacts Their Lifespan
The location where you store your respirator and filters can affect their shelf life. When not in use, keep them protected from the elements. away from direct sunlight, oil, and corrosive environments. We recommend that you ensure that respirators are clean and dry before storage, one could use either a sealed storage bag or preferably containers to keep them better protected.
It’s crucial to understand that various factors can shorten the service life of gas and chemical respiratory filters. Using these filters past their recommended service life poses serious risks to worker safety and can be in violation of workplace health and safety regulations.
At Fit Test Australia, we recommend that you educate yourself on the correct filters to use, and then develop an effective filter change schedule for your workplace, adjusting it regularly to ensure maximum protection for your workers.
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