3M Half Facepiece Respirator (7500)

Even though we've know about the side effects of dust inhalation for many years, my suspicion is that many woodworks still adopt somewhat of a 'laissez-faire' attitude to the whole topic. I'm amazed at the number of times I've visited both production and hobbyist shops where respiratory protection was virtually non-existent or barely adequate. When queried, the inevitable response is that 'we have a very efficient dust collection system.' Unfortunately, a dust collector doesn't pick up all the dust produced in a workshop, particularly very fine dust. Nor is it effective in protecting you when using power sanders or sanding by hand. Ambient air cleaners are somewhat more efficient in removing fine dust from a work area, but in the long run, the best kind of protection is personal protection in the form of high quality dust masks or respirators. Wood dust is not only a known carcinogen (targeting the nasal passages), but can exacerbate dermatitis, rhinitis, asthma, eye and throat irritations, and various allergic reactions.

For years I used standard disposable dust masks. I'm not certain whether they were all the effective, given how ill-fitting most of them were. A short while ago I decided to try a 3M Half Facepiece Respirator (7500). The 7500, also called a half-mask respirator, comes in three sizes, small (#7501), medium (#7502) and large (#7503). Typically they are sold without filters. The 7500 can be used with any of the 3M filters and cartridges (series 2000, 5000, 6000 and 7093).

There are three categories of filters for this mask. Particulate filters, designed to trap dust, mists and fumes, aerosols, smoke, mould, and bacteria, will be most useful to woodworkers. Gas and vapour cartridges are used in environments subject to various gases and vapours. These would be more appropriate when you're applying finishes, particularly if you use spray equipment. Finally, there are Combination cartridge/filters that can be used for particulates, gases, and vapours. 3M makes a lot of filters and cartridges for the 7500. You can get more information on their full line here. I chose to try the #7093 particulate filter, which offers a very high level of protection at a reasonable price (about $20 for a package of 4). Filters are rated at different efficiencies (the percentage of particulate that the filter will remove from the air). The #7093 filter is rated N100, meaning that it has a minimum efficiency of 99.97%. That's probably cleaner than the air outside my shop.

Form fitting silicone facepiece

The Exhalation Valve

The 7500 is a very light mask, weighing in at about 8 ounces. The housing is made of a durable high impact ABS plastic, while the facepiece is made of a soft, pliable silicone that fits snugly and comfortably around the mouth and nose. There is an adjustable plastic headband that sits atop your head, and a set of elastic straps that hold the bottom part of the mask snugly around your neck. At the front of the 7500 is a Cool Flow Exhalation Valve; dust laden air is drawn through the filters where the dust particles are removed, before being vented out through the valve.

The 7093 filter

A simple twist connection mounts the filter to the mask

A simple twist connection mechanism holds the filters onto the mask. Installing or removing each filter takes the better part of 3 seconds. Once you've initially adjusted the mask to fit your face, strapping it on is likewise very fast, taking about 10 seconds. The straps can be easily adjusted for a snug, comfortable fit.

I found the 7500 very comfortable to wear even for extended periods of time. The flexible silicone facepiece conforms easily to the shape of your face, and does a very effective job of keeping debris out. It's easy to put on and take off, and, you don't have to yank the straps very tightly to effect a snug fit. There was no perspiration build-up on the inside of the mask, and co-workers can hear me through the mask without having to raise my voice.

Best of all, the 7093 filters remove over 99% of the dust that otherwise would end up my nose and in my lungs. I've been using these same filters for almost six weeks, and they're still going strong. According to 3M they need to be replaced when it becomes difficult to breathe comfortably, or if the filters get damaged. The mask is reasonably priced at around $40, while filters are about $10 a pair. Very good value for superior respiratory protection.

Important note for those with facial hair:

3M points out that tight fitting respirators, like the 7500 series, should not be used by people with facial hair. This confirms to the Canadian Standards Association regulation Z94.4. The reason is that air will follow the path of least resistance; if there is facial hair in the seal, the air will flow through that path and not through the filter and/or cartridge. For woodworkers with facial hair 3M recommends a loose fitting powered air purifying respirator. There are a number of these respirators on the market, including the popular 3M Airstream.

Reviewed November 2010