Why and when should I wear a dust mask?

Question

I'm a handy man with limited woodworking projects these days. I mostly use a circular saw, jig saw, and orbital sander to make crude storage. Sometimes I cut MDF, etc.

I've seen it mentioned several times on this site that you should wear a dust mask. Then I saw this answer which said, "Dust collection is not an excuse not to wear a mask."

• Why does it seem mandatory to wear a dust mask?
• When is it not mandatory to wear a dust mask?
• I work mostly outside with a breeze as my dust collection, am I ok?
• Is wearing a dust mask more important when using certain tools?

The types of wood that you should wear a dust mask for has already been discussed. I'm asking in particular about work environment, situation, and type of work.

Answer 1

Short answer: always wear a properly-fitted, high-efficiency respirator so you can reduce your chances of developing respiratory problems or certain types of cancer of the respiratory system later in life.

There are many levels of protection when it comes to filtering the air you breathe, from cheap paper masks that provide very little protection, to slightly better disposable masks with or without breathing valves, to well-fitted half- or full-face respirators with rubber gaskets and P100 filters (HEPA-level, removing 99.97% of airborne particles down to 0.3 microns in size).

No matter how good your dust collection system is, some dust will always escape at the collection point and some may not be filtered at the filtration point.

To answer the various points in your question:

Why does it seem mandatory to wear a dust mask?

Because inhaled dust can clog up your lung tissues. In the short term, you can become sensitized to certain types of material, and longer-term you can develop respiratory ailments and/or cancer. Not everyone is as susceptible to any of these negative outcomes, but there is not a way to predict whether you will be one of the unlucky ones who does develop some sensitivity or ailment.

When is it not mandatory to wear a dust mask?

Strictly speaking, never. If we all wore respirators 24/7 and never removed them, we could reduce the spread of airborne diseases, reduce inhalation of secondhand smoke and automotive exhaust, and generally keep our lungs cleaner.

But there's a point at which protecting yourself from future ailments becomes impractical or seems excessive (even ridiculous), given all the other hazards we face on a daily basis. And not everyone who is subjected to dust develops cancer or any other ailment. Only you can decide what level of risk you are willing to accept for yourself. Personally, I go by whether I can smell the dust, which means I almost always wear a respirator, even when working outside.

I work mostly outside with a breeze as my dust collection, am I ok?

You're certainly better off than being in an enclosed space in which the concentration of airborne particles increases the longer you work, assuming you are not wearing a respirator in either case. But you're not necessarily as well off outdoors without a respirator than you are indoors with a respirator, especially with tools that produce a cloud of dust around you when you use them.

Is wearing a dust mask more important when using certain tools?

Yes, some tools produce more dust or finer dust, some tools collect less dust, and some tools eject more dust directly toward you. It all depends on the tool, application, and whether the tool was adequately retrofitted or designed from the start with dust collection in mind. For example, most circular saws have little or no dust collection, while most track saws at least have a dust collection port built in or available as an add-on. And most sanders these days have dust collection ports but some work better than others. Most miter saws currently on the market have terrible dust collection, but many table saws have pretty decent dust collection.

Answer 2

As with Rob, the short answer is to always wear a dust mask to reduce the risk of respiratory problems.

The long answer is, it depends. Visible dust is less of a hazard than very fine particles. Dust particles smaller than 10 microns can bypass the body's defenses and can reach deep within the lungs. Particles larger than 10 microns tend to be trapped by the bodies natural filters (nose, throat, etc).

Dust danger is also relative to the volume of air it is being disbursed in. If you work in a garage with the large door open, your air is being replaced at quite a rapid rate. Working in a small, fully enclosed shop, the dust can linger for quite a long time, and thus more care needs to be taken.

Exposure time is also a factor. If you are exposed to dust for an hour or two every week, you have less risk than someone who spends every day in the shop.

Certain woodworking activities don't produce much in the way of very fine dust. Most of the dust from saws, planers, drills, and even routers is consists of much larger particles. Sanding is probably the worst culprit for producing very fine dust, so wearing a mask while sanding with power sanders is more important than most other times.

Some tools, notably Festool, offer very good dust collection built right into their tools. Prior to investing in a Festool dust collector and their sanders, I typically would wear a mask while sanding, or did my sanding outside.

Regarding shop vacuums in general, they can be worse for your lungs than nothing at all. Most inexpensive ones do not have the required HEPA filters and while they pick up all of the visible dust, they are expelling the more dangerous, very fine dust into the air. A HEPA filter, such as the ones Festool uses, will capture dust down to .3 microns. If you don't have a good HEPA filter (and maybe even if you do), you should wear a good dust mask while and after a shop vac has been operating.

As far as filters, you want at least an N95, with N99 or P100 being better. The mask needs to seal tightly against your mouth and nose - get one in the correct size. Facial hair makes it harder to get a good seal, so you might need to consider a forced air face shield if you are not getting enough filtration.

Links for further reading:

Article 1

Allergy Mask Guide

Answer 3

I'm new to sanding. I have just taken up furniture restoration as a hobby. 4 days ago I sanded outside for 2-3 hours with out a mask. I have been in bed 2 days solid so far with flue like symptoms and a tight chest. Doctor says it's inhalation fever... Trust me when I say wear a mask, you do not want to feel like this!

Answer 4

Make it easy on yourself And your health by wearing a properly fitted respirator whenever Any dust or other particles may be generated.

You don't have to see anything for there to be a hazard; in fact, the less you see the more likely it is that the particles are very small and therefore more dangerous.

Make sure anyone else hanging around where you are working also wears a respirator.

I live in a city of around 100,000 population in the middle of a windy valley with agricultural activity all around. Lots of dust gets stirred up here. It's nearly impossible to know what all is in that dust, but what little I do know is more than enough to make me cautious.

In the last couple of weeks I have begun wearing a GVS half-mask P100 respirator as much of the time as possible because of all the junk in the air everywhere, and I don't have any history of breathing problems.

Bugger anyone who thinks I'm daft or being silly. I say it's better to look the fool and be healthy than to be sick or dead. Admittedly I'm still very self-conscious about where I wear it and too often remove it because of how others might react, but I'm working on that.

So, if you see some guy with his snout stuck in a small blue-mauve bowl with pleated white panels on the sides, wave hello. You should probably be imitating him.