Masks & RespiratorsComments (0)
This article is from Issue 50 of Woodcraft Magazine.
Read this now. Breathe easier later.
By Chris Hill
As woodworkers, we know that our passion can bite us back if we’re not careful. But while spinning bits and blades are easy to see, other threats aren’t so visible. Breathing in airborne particles and chemicals can trigger an immediate allergic response and/or cause respiratory problems. Over time, prolonged exposure to these contaminants can contribute to a host of life-threatening ailments.
Dust collectors and air filters help reduce what’s in the air, but neither provides the frontline defense you’ll get by donning a mask or respirator. Here’s a quick rundown of the available types so you can select exactly what you need to protect yourself from the dangers that might already be floating around in your workshop.
3M P95 Mask
Convenient and cost-effective, disposable masks are the first choice for woodworking and assorted DIY projects, but it’s important to match the mask to the task. Despite what some think, the N-rating doesn’t stand for “nuisance” (see, “Know The Code,” at right). N-rated masks should be used for limiting exposure to non-oily hazards such as sawdust, drywall dust, pollen, and mold. Most woodworkers find that N95-rated masks provide sufficient protection, but if you suffer from acute sensitivity, or if you work with toxic woods, consider stepping up to N100. (This extra protection comes at a price. N95 masks cost about $2 apiece, N100s start at $8.)
Beyond the National Institute for Occupational Safety and Health (NIOSH) specs, a few additional features are worth the upcharge. To ensure a good fit, look for masks sporting dual-elastic straps and moldable nose bridges. An exhale valve will help the mask feel cooler and minimize breath-induced fogging of your safety glasses. (You are wearing safety glasses, right?)
Masks don’t last forever. Few of us replace a mask every time we pull it from our face (as suggested), but you should discard it at the end of the work day, or when you have any difficulty breathing through it.
Know The Code
Picking the right mask or respirator starts by understanding the rating system of the National Institute for Occupational Safety and Health. An “N” indicates a mask that is non-oil resistant. An “R” indicates some oil-resistance. An R-rated filter should be discarded after eight hours of use. “P” indicates better oil-resistance. A P-rated filter can last for 40 hours of use, or 30 days, whichever comes first.
The number following the letter indicates filter efficiency. Filter materials are tested against particles having a diameter of 0.3 microns (100 times smaller than the diameter of a human hair). Filters with a “95” rating are 95% effective. Filters bearing a “100” are 99.97% effective.
Filter cartridges bear additional numbers on the package or on the cartridge itself. These indicate the chemicals that the filter can provide protection against, such as chlorine and ammonia.
Half-face respirators are suitable for dust protection, but they can also be equipped with cartridges that chemically capture toxins that pass through mechanical filters. For this reason, respirators are the required dress code when applying a spray finish, stripping furniture, or doing a similar hard-core chore. Note that cartridges alone do not protect wearers from particulates. For environments that contain both harmful particulates and vapors, wearers must use combination filters that have chemical and mechanical filtration. To capture particles that might prematurely clog the cartridge, many combination units employ a replaceable prefilter. The easy way to identify the most efficient filters and prefilters is by color: P100 filters are pink.
With regular maintenance, respirators can easily outlast a box of masks. To extend the life of filter cartridges, replace prefilters after eight hours of use, or when you detect a change in airflow. To make certain that you don’t use a cartridge that’s past its prime, record the date and length of time used. If your filter exceeds the recommended expiration time or you smell or taste any chemical when working, replace it. (Note that some cartridges continue to absorb air even when they’re not in use. To extend a respirator’s working life, store it in a resealable container.) If you’re not planning to spray on a regular basis, consider a disposable respirator. Simply unpack it, spray, and then toss it away.
Some woodworking activities, like turning or power-carving, generate a constant barrage of chips and dust. Here, toxic fumes aren’t the issue, but comfort is. The mask must be comfortable enough to be worn for hours at a time. Powered respirators employ a blower that forces air through the filter. In addition to the cooling effect, the fan establishes positive air pressure, which eliminates the need for a face-tight seal like other masks or respirators.
Comfort has its price, however. In addition to the higher price tag, the constant air flow causes the filters to clog more quickly.
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