Since a lot of this is what I do in my day job, I thought I'd toss it out there for you guys. I'm sure most of you guys know this stuff already but, hoping someone gets something from it..
Respiratory Protection – Breaking Down What You Need in the Shop
The woodworking hobby is a very dusty hobby that requires respiratory protection. The hobby also has the woodworker in contact with many other chemicals and substances that also requires respiratory protection. Unfortunately, not all respiratory protection is the same and there’s not a lot of information in the community to help the woodworker determine what they need and when. What follows should help provide some of those answers.
It’s important that everyone is speaking the same language! I’ll give you some “official” definitions and then try and break it down to what that means for the hobbyist woodworker.
HEPA Filter/Cartridge - are designed to reduce inhalation exposure to particulate contaminants. In general industry, these respirators are used to decrease exposure to particulates such as wood dust, animal dander, and pollen.
Often referred to as a “P100”, this is the filter you want for normal dusty activities.
Organic Vapor Filter/Cartridge - filter that removes gases, volatile organic compounds (VOCs), and other vapors from breathing air through adsorption, absorption, or chemisorption.
Usually referred to as an “OV” cartridge, this is the cartridge you want when spraying solvent based finishes or other items with strong odors
Piggy Back or Stacked Filter/Cartridges – I could not find a “book” definition for these but, they’re essentially just a stacked filter that protects the user against multiple respiratory hazards.
For the hobbyist woodworker, the most common stacked filter would be the HEPA (P100) and the Organic Vapor (OV) cartridge. It should be noted that these filters are a little harder to breathe through because you’re trying to breathe through to filter mediums.
Working Life – This question comes up often and will vary from manufacturer to manufacturer. It’s also dependent on what you’re filtering, how often you’re using it, and how long. Here’s a couple rules of thumb regardless of the manufacturer.
HEPA - When a filter gets clogged with dust and other debris , you will find it is harder to breathe. There is less room for air to move through the filter and into your lungs, and so the breathing resistance increases. This would be a good time to replace the filter.
Organic Vapor - As the cartridge portion becomes exhausted, it no longer blocks the smell of solvents and other chemicals. As you notice strong odors that weren’t there before, it’s a sign that it’s time to replace your cartridge.
Storage - All of the above listed respirators/cartridges should be stored in a sealed bag when not in use. This will improve cartridge life as well as ensure the mask is not contaminated when needed.
Powered Air Purifying Respirator - A type of respirator used to safeguard workers against contaminated air. PAPRs consist of a headgear-and-fan assembly that takes ambient air contaminated with one or more type of pollutant or pathogen, actively removes (filters) a sufficient proportion of these hazards, and then delivers the clean air to the user's face or mouth and nose. They have a higher assigned protection factor than filtering facepiece respirators such as N95 masks. PAPRs are sometimes called positive-pressure masks, blower units, or just blowers.
There are numerous manufacturers of these and are often cost prohibitive to the hobbyist woodworker. They are being used more frequently by wood turners as they protect the entire face as well as give better respiratory protection than a ½ mask with appropriate cartridges.
Assigned Protection Factor (APF) - means the workplace level of respiratory protection that a respirator or class of respirators is expected to provide to employees when the employer implements a continuing, effective respiratory protection program.
This is probably going a bit deeper than we really need to as hobbyist woodworkers but, I think it’s good information to understand. There’s a significant difference between ½ mask respirators, full face respirators, PAPRs, and Fresh Air respirators! The APF is actually increased in the same order that I listed them. The illustration below is borrowed directly from OSHA to show the difference.
Fit Testing - A fit test should not be confused with a user seal check. A user seal check is a quick check performed by the wearer each time the respirator is put on. It determines if the respirator is properly seated to the face or needs to be readjusted.
There are two types of fit tests: qualitative and quantitative.
Qualitative fit testing is a pass/fail test method that uses your sense of taste or smell, or your reaction to an irritant in order to detect leakage into the respirator facepiece. Qualitative fit testing does not measure the actual amount of leakage. Whether the respirator passes or fails the test is based simply on you detecting leakage of the test substance into your facepiece. There are four qualitative fit test methods accepted by OSHA:
Isoamyl acetate, which smells like bananas;
Saccharin, which leaves a sweet taste in your mouth;
Bitrex, which leaves a bitter taste in your mouth; and
Irritant smoke, which can cause coughing.
Qualitative fit testing is normally used for half-mask respirators - those that just cover your mouth and nose. Half-mask respirators can be filtering facepiece respirators - often called "N95s" - as well as elastomeric respirators.
Quantitative fit testing uses a machine to measure the actual amount of leakage into the facepiece and does not rely upon your sense of taste, smell, or irritation in order to detect leakage. The respirators used during this type of fit testing will have a probe attached to the facepiece that will be connected to the machine by a hose. There are three quantitative fit test methods accepted by OSHA:
Ambient aerosol; and
Controlled Negative Pressure.
Quantitative fit testing can be used for any type of tight-fitting respirator.
That’s a lot to take in considering the hobbyist woodworker is not going to go through this process. I added it simply to show what the OSHA requirement is to wear these masks that we’re all wearing.
The seal check should be performed each time you put your respirator on. Simply cover the cartridges and attempt to breathe in. If the mask sucks tight to your face and you can’t inhale, you have a good seal. If air is leaking by, either the mask is too big or small for your face or you may need to remove some facial hair.
I’ve heard it said often that “at least I’m doing something to protect myself” from those with facial hair. This is false. Users that wish to maintain their facial hair should upgrade to a PAPR hood style respirator for adequate respiratory protection.