Page 36 - OHS, October 2022

PPE: RESPIRATORY PROTECTION
Choosing the Right Respiratory Protection
It is important for you and your workers to have confidence in your safety equipment.
BY TOM BURGESS
When it comes to selecting respirators for the work environment, numerous resources are available from respirator suppliers, the OSHA respirator selection e-tool, the National Institute for Occupational Safety & Health (NIOSH) and other resources. However, we can still end up with a wide and daunting range of choices and considerations.
Is an N95 filter good enough, or should we be using a P100? Should we use an organic vapor or combination cartridge, and when do we need a filter? How long will cartridges last, including if we don’t use them regularly?
Filters
Filters are used for solids or liquids suspended in air. The term “aerosol” includes any suspension of tiny particles or droplets in the air, such as dusts, mists or fumes. “Fumes” is a commonly misused term, and for respirator selection, it is important to distinguish between fumes and vapors. Fumes are solid particles generated by condensation, such as during welding— when vaporized metal condenses into solid particulate fumes. Vapors, on the other hand, are the gaseous form of a liquid or solid substance. It is possible for fumes to pass through a vapor cartridge and also for vapors to pass through a filter. The correct
terminology is important and for protection from fumes, we want a filter.
The ongoing COVID-19 pandemic has made everyone familiar with the term “N95.” This is commonly used to refer to the N95 filtering facepiece respirator, but the N95 designation applies to any filtering apparatus meeting the NIOSH specifications, including those used with half or full-face respirators. The selection of an N, P or R filter rating depends on the need for oil resistance, as oils can degrade the filter media. N is not resistant to oil, R is resistant to oil and P is oil-proof.
The three levels of filter efficiency are 95 (95 percent), 99 (99 percent) and 100 (99.97 percent). The term “high-efficiency” or “HEPA” is used with filters for powered air purifying respirators with a 99.97 percent efficiency.
The NIOSH filter efficiency rating is based on how well it can filter a 0.3 micrometer (μm) diameter aerosol. The 0.3 μm diameter is approximately the most penetrating particle size for particulate filters. Although it’s contrary to expectation, smaller particles do not penetrate as readily as 0.3 μm particles. Therefore, these respirators will filter all other particle sizes at least as well as the certified efficiency level.
How much more protective is a 100-rated filter compared to
32 Occupational Health & Safety | OCTOBER 2022
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