APF — assigned protection factor

CFR — Code of Federal Regulations

DFM — dust, fume, and mist

DHHS — U.S. Department of Health and Human Services

DM — dust and mist

DOP — dioctyl phthalate

HEPA filter — high-efficiency particulate air filter

HR — hazard ratio

IDLH — immediately dangerous to life and health

MMAD — mass median aerodynamic diameter

MSHA — Mine Safety and Health Administration

NaCl — sodium chloride

NIOSH — National Institute for Occupational Safety and Health

OSHA — Occupational Safety and Health Administration

PAPR — powered air-purifying respirator

PEL — permissible exposure limit

REL — recommended exposure limit

SCBA — self-contained breathing apparatus

TB — tuberculosis