Dust masks and respirators for home projects

An N95 is a disposable respirator that seals around your nose and mouth and filters particles such as dust, mist and fumes. NIOSH, the federal agency that tests and approves respirators, calls it a filtering facepiece respirator. A mask labeled "N95" that's missing the required markings isn't approved and may not protect you.

What it filters, and what it doesn't

An N95 filters at least 95 percent of the particles in the air. It doesn't stop gases or vapors. Sanding dust is a particle, so an N95 works for it. The smell of a solvent or a strong cleaner is a vapor, and an N95 does nothing for that.

The letter tells you how it handles oil:

• N. Not resistant to oil.
• R. Somewhat resistant to oil.
• P. Strongly resistant to oil.

The number is the share of particles it filters: 95, 99, or 99.97 percent for a 100.

Telling an approved one from a fake

An approved N95 has all of these printed on the mask itself:

• The maker's name, or the brand it's sold under
• NIOSH in capital letters, or the NIOSH logo
• A TC approval number, such as TC-84A-XXXX
• The filter class, such as N95, N99 or P100
• A model or part number

The quickest check is to search the TC number on NIOSH's Certified Equipment List.

Putting it on

How well a respirator works depends mostly on how well it fits, so follow the instructions that come with your model. At work, an N95 user is fit-tested. At home, do a seal check every time you put one on:

• Breathing out. Cover the mask with your hands and breathe out gently. You should feel slight pressure build inside, with no air leaking around the edges.
• Breathing in. Cover the mask and breathe in quickly. The mask should pull in a little toward your face.

A seal check doesn't replace a fit test. A mask with an exhalation valve is easier to breathe out through and more comfortable to wear.

When to throw it away

You can usually keep wearing one until it's damaged, dirty or noticeably harder to breathe through. Between uses, store it where it's protected from dust, sun, heat, moisture and chemicals, and where it won't get crushed. If the package says single use, use it once.

For a small mold cleanup

Wear an N95, gloves, and goggles without vent holes when you clean up mold. Small mold cleanup covers the job itself.

An annotated example

What to do next

Look at the respirators you already have for NIOSH and a TC number, and keep spares sealed in a drawer out of the sun. Older paint is its own hazard: lead paint in homes built before 1978 covers it.