Air-Purifying Respirator 4 : Breathing apparatus with an air-purifying filter, cartridge, or canister designed to remove air contaminants by passing ambient air through the air-purifying element. [air quality]
CoTradeCo Glossary of Critical Industrial Safety Terms and Other Important Words, Abbreviations and Acronyms, La Quinta, CA., USA 2010. https://cotradeco.com/pages/52-glossary-of-critica l-terms-abbreviations-ratings-regulations, (IndS - Amer) {36}