3M, Moldex & SAS Dust Masks

The number following is an indication of filter efficiency. Filter materials are tested against particles having a diameter of 0.3 microns. This is an extremely small particle. Contrast with human hair, whose diameters range from 40 microns to 120 microns. So, the number will indicate relative efficiency, with the "95" being 95% effective. The "100" is 99.97% effective, and is the current means of referring to a "HEPA" filter.

To ensure that these disposable dust masks are providing the protection advertised, Fit Testing is recommended. A less than optimum fit will allow unfiltered air to bypass the filter media and take the path of least resistance.

In general, all of these masks should be discarded after they become soiled, or breathing becomes difficult due to filter loading.

3M and SAS masks have an adjustable metal noseclip. This soft aluminum strip may be molded to aid in getting a fit. The Moldex dust masks have a pre-molded shape that fits most (though not all) users.

One-way valves allow exhaled air to leave the mask directly. This helps keep the mask cooler, which is a big comfort advantage. This also helps reduce fogging on safety glasses. However, in the case of influenza or 'flu' applications, it should be noted that the infected person should not be using a vented mask, as the disease carrying mist will be allowed to pass unfiltered out to the atmosphere.

Masks rated N95 and higher have been recommended for protection against Avian flu, Bird flu, Tuberculosis / TB and SARS. Please e-mail us with questions about your specific work environment.