When to use a 95%, 99% or 100% Filter

ORGIN: Moldex Technical Services Department
DATE: June 26, 2003


Questions often arise as to which filter efficiency should be chosen to protect against a specific particulate contaminant.

For contaminants not covered by a substance specific statute, the choice of efficiency level will be dictated by your customers’ evaluation of their hazards and need for protection. (Asbestos, lead, inorganic arsenic and cadmium are covered as described below.) All NIOSH approved filters are tested against the most penetrating size of the particle and therefore will filter out the contaminant in question.

Use Of A 95% Filter:

Since all half mask respirators receive an Assigned Protection Factor (APF) of 10, use of a 95% filter will usually be adequate. The choice of an N, R or P filter will depend on the presence of oils.

Use Of A 99% Filter:

Use of a 99% series is usually unnecessary because even with these higher efficiency filters you can still only receive an APF of 10. There may be some situations where the customer may want to use a 99% series filter, especially in welding situations, where they may simply choose a higher level of filter for the users’ comfort and/or protection. The choice of N, R or P depends on whether oils are present.

Use Of A 100% Filter:

For contaminants falling under a substance specific standard requiring a High Efficiency Particulate Air (HEPA) filter, an N100, R100 or P100 series filter must be used. These substances are asbestos, lead, inorganic arsenic, cadmium and MDA. The choice of N, R or P will depend on whether oils are present. Some of these chemicals may require a chemical cartridge in addition to N, R, or P filter. For asbestos the 8000 series facepiece must be used.

There may be other situations where a qualified health professional may recommend a 100% filter.

: The information contained in this Tech Brief is dated and was accurate to the best of Moldex’s knowledge, on the date above. It is not meant to be comprehensive, nor is it intended to be used in place of the warning/use instructions that accompany Moldex respirators. Outside of the USA, check with all applicable and local government regulations.

©2003-2010 Moldex-Metric, Inc. All Rights Reserved.

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