Definitions (Section 4)

Atmosphere, hazardous. Any atmosphere that is oxygen deficient or contains a toxic contaminant exceeding the occupational exposure limit (see occupational exposure limit)

Atmosphere, oxygen deficient. An atmosphere containing less than 19.5 percent oxygen by volume

Cartridge, air-purifying. A container with a filter, sorbent, or catalyst, or any combination thereof, which removes specific contaminants from the air drawn through it

Contaminant. A harmful, irritating, or nuisance material that is foreign to the normal atmosphere

Dust mask. A negative pressure particulate respirator with a filter as an integral part of the facepiece or with the entire facepiece composed of the filtering medium. This does not include single strap comfort masks or surgical masks, which do not create a negative pressure seal against the skin of the face.

Facepiece. That portion of a respirator that covers the wearer's nose and mouth

Fit test. The use of a protocol to evaluate qualitatively or quantitatively the fit of a respirator on an individual

Fit test, qualitative. A pass/fail fit test to assess the adequacy of respirator fit that relies on the individual's response to the test agent
Fit test, quantitative. An assessment of the adequacy of respirator fit by numerically measuring the amount of leakage into the respirator

Immediately dangerous to life or health (IDLH). Term for describing an atmosphere that poses an immediate threat to life, would cause irreversible adverse health effects, or would impair an individual's ability to escape

Occupational exposure limit (OEL). An exposure limit that is the lower of the permissible exposure limit or threshold limit value (see permissible exposure limit or threshold limit value)

Permissible exposure limit (PEL). An exposure limit published and enforced by the federal Occupational Health and Safety Administration (OSHA) as a legal standard. A PEL may be either a time-weighted-average (TWA) exposure limit (eight hour), a 15-minute short-term exposure limit (STEL), or a ceiling (C) and may have a skin designation.

Respirable. Able to be breathed. Also refers to particle size diameter less than or equal to 10 micrometers

Respirator. A device designed to protect the wearer from the inhalation of hazardous atmospheres. This does not include single strap comfort masks or surgical masks which do not create a negative pressure seal against the skin of the face.

Respirator, air-purifying (APR). A respirator with an air-purifying filter, cartridge, or canister that removes specific air contaminants by passing ambient air through the air-purifying element
Respirator, negative pressure (tight fitting). A respirator in which the air pressure inside the facepiece is negative during inhalation with respect to the ambient air pressure outside the respirator

Respiratory protection. The process of using a respirator properly to prevent harmful inhalable substances from entering the lungs

Service life. The period of time that a respirator, filter, or sorbent, or other respiratory equipment, provides adequate protection to the wearer

Spirometry. A basic pulmonary function test that measures how much and how fast air moves out of the lungs

Threshold limit value (TLV). Recommended guidelines for occupational exposure to airborne contaminants published by the American Conference of Governmental Industrial Hygienists (ACGIH). TLVs represent the average concentration for an eight-hour workday and a 40-hour workweek to which nearly all workers may be repeatedly exposed without adverse effect.

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