Guide to respirator ratings
Two-strap disposable respirators can be very effective at filtering particulate out of the air.
They represent a good middle ground between single-strap nuisance dust masks (which are only minimally effective in the most benign circumstances) and the more expensive respirators with replaceable filters that are manufactured to protect from specific hazards (asbestos, paint fumes, etc.).
Two-strap respirators come in three classifications (N, P, and R) and with three efficiency ratings from the National Institute for Occupational Safety and Health (NIOSH). Understanding these ratings will ensure you choose the right respirator to protect your health.
Disposable respirators are designed to filter out airborne particulate, which is basically dust, mist and fumes. They will not filter uncondensed vapor and gases, and if particulate concentration levels are too high disposable respirators are typically inadequate.
Disposable respirators are typically safe enough for most general construction tasks in partially vented workspaces. Make sure your respirator fits properly and seals to your face – especially around the chin and at the bridge of the nose. An incorrect fit that leaks air will eliminate the protection offered by the respirator.
N-, R- and P- ratings represent different levels of resistance to airborne oil particles that can degrade the filtration efficiency of a respirator.
- N (Not oil resistant) – Good for remodeling a moldy basement, sanding drywall, etc.
- R (Oil resistant) – Good for use against solid and liquid particulates that may contain oil. R rated respirators typically have a service life of eight hours before they should be thrown away.
- P (Oil proof) – Similar to R-series respirators, but if the mask is not damaged or breathing resistance is not detected, they can be used indefinitely.
NIOSH ratings are simply a way to quantify how much airborne particulate a respirator can filter. Filters labeled “95” can filter at least 95 percent; “99” filters, at least 99 percent; and “100” filters, at least 99.97 percent.
An N95 respirator is not oil resistant and filters 95 percent of airborne particulate. A P100 respirator is at the other end of the spectrum; oil resistant and filters virtually all particulates. P100 respirators are often called HEPA masks.
If you are not sure which mask is most appropriate for the work you are doing, check the NIOSH website, the product MSDS sheet, and the respirators manufacturers’ websites, which often have product selector guides to aid in choosing.
If you are unsure about an environment’s particulate concentration level, then have an air-quality/workplace safety company well versed in air testing take extensive samples. This is especially important when working in enclosed areas with little to no ventilation.
–By Rob Fanjoy