When talking about employee exposure we are interested in the airborne concentration of contaminants that would occur if the employee were not using respiratory protection. Knowing this concentration of contaminants, we can then determine the level of protection that the employee will need to work in a safe environment. Let's look at some definitions before we get into the specifics of the program:
A respiratory inlet cover is that portion of the respirator that forms the protective barrier between the user's respiratory tract and an air-purifying device.
HEPA filters are very fine filters which will remove particles as small as 0.3 microns (3/10 of one millionth of a meter) in diameter.
A canister or cartridge is a device that contains a filter or some kind of material that will remove a specific contaminant from the air passed through it.
Service life refers to the period of time that a respirator filter provides adequate protection to the wearer.
ESLI (estimated service life indicator) is a system that warns the wearer of the approach of the end of adequate protection. Some filters will have a color change indicator built in. Later we will talk more on how our program has built in a system to track respirator filter use and how we can monitor filter change out schedules.
A negative pressure respirator means that the pressure inside the facepiece is negative with respect to the outside air.
A positive pressure respirator is a device in which the pressure inside the mask is greater than the ambient air pressure.
A dust mask is composed mainly of a filtering medium.
APR (air purifying respirator) is a respirator with an air purifying cartridge that removes specific contaminants by passing air from the ambient environment through the filtering device.
PAPR (powered air-purifying respirator) uses a blower to force ambient air through the filtering elements into the respiratory inlet cover.
Atmosphere Supplying air respirator - supplies user with air from a source independent from the ambient air - includes SAR (supplied air respirator) - source of air not designed to be carried by user and SCBA (self-contained breathing apparatus) - air source is carried by user.
Escape only respirator - only to be used in emergency.
User seal check should always be conducted before using respirator.
A pass/fail qualitative fit test will be used to test the adequacy of the respirator fit. The test we use at NSCC is the Bitrex test.