Maximum design protection cannot be achieved unless the face piece is carefully fitted to the wearer's face. A tight fit is necessary to prevent inward leakage of contamination. The proper type of canister, cartridge, or filter must be selected for the particular atmosphere and conditions. For airborne chemical contaminants, an end of service life indicator must be provided on filter cartridge or the employing department must implement a cartridge change schedule. Resistance may cause discomfort or aggravate a medical condition.
Powered respirators minimize the problems associated with breathing resistance.
Prescription spectacles may not work with respirator face pieces. However, special spectacles or spectacle holders are available. Temperature rise in canister or cartridge indicates that a gas or vapor is being removed from the inspired air. An uncomfortably high temperature indicates a high concentration of gas or vapor and requires an immediate return to fresh air. Atmosphere Supplying Respirators Atmosphere supplying respirators provide protection against oxygen deficiency and toxic atmospheres.