Talk about Reusable air-purifying respirators

Reusable air-purifying respirators (APRs) in more defined terms, also called Elastomeric respirators, are a type of respirator that seals to the face using a mask made of an elastomeric material, may be natural or synthetic rubber, they could be half facepiece or full facepiece.
CoAir-purifying respirators consist of a reusable mask that seals to the face, with exchangeable filters cartridges, or flexible, disc or pancake-style filters, which are not housed in a cartridge body, can be repeatedly used, cleaned, disinfected, stored, and re-used.
Work by removing gases, vapors, aerosols (droplets and solid particles), or a combination of contaminants from the air through the use of filters, cartridges, or canisters. These respirators do not supply oxygen and therefore cannot be used in an atmosphere that is oxygen-deficient or immediately dangerous to life or health. The appropriate respirator for a particular situation will depend on the environmental contaminants.
air-purifying respirators are reusable because the facepiece is cleaned and reused, but the filters are discarded and replaced when they become unsuitable for further use. Some, but not all, filter materials are proprietary and manufacturer-specific, and supply-chain failures can make replacements hard to find.
Provide an alternative respiratory protection option to FFRs for protection against pathogens. These respirators may also serve as protection against other airborne hazards in healthcare settings. However, they require maintenance and a supply of replaceable components including straps, inhalation and exhalation valves, valve covers, and filters, cartridges, or canisters.
While it is often possible to decontaminate the hard outer casing of filters, the filter material itself typically cannot be cleaned or disinfected for reuse. Instead, filter components should be discarded when they become damaged, soiled, or clogged.

Elastomeric respirators have the same basic requirements for an OSHA-approved respiratory protection program as filtering facepiece respirators, including medical evaluation, training, and fit testing. The use of a NIOSH-approved respirator is required by OSHA. OSHA also requires that respirators be used in conformance with the conditions of their NIOSH certification. Hence, a NIOSH-approved respirator assembly cannot be modified, and only those replacement parts specified and provided by the manufacturer must be used. The manufacturer’s instructions are specific to its respirator materials and specifications. Manufacturer instructions are generally provided with the respirator facepiece packaging.
Respirators with full facepieces have the same filter considerations but provide greater protection because of better sealing characteristics and less face seal leakage and also provide protection to more of the face and very importantly, the eyes.

Two types of respirators are air-purifying respirators (APRs) and air-supplying respirators. The latter, either have a self-contained air supply or are supplied by an external air source.
Have basic component:
A face mask.
A filter or cartridge filter to remove dust, smaller particles, and mists.
A cartridge filter to remove chemical gases and fumes.

Filter Types
There are several types of filter media for use with NIOSH-approved reusable, half-facepiece elastomeric respirators. All are sufficient at removing droplet and viral size particles when worn correctly for the duration of the exposure. Filters are available in three efficiency levels – 95, 99, 100.
the mask ad filter comes in a variety of standards for mechanical filters and chemical cartridges, intended for a variety of purposes. An appropriate standard of the filter must be used for the mask to be effective.
Filters may be contained in cartridges or canisters; Filters are usually mounted on the face, but in the case of powered air-purifying respirators, they are mounted on the belt, and a fan drives air through them and into the face mask. Most masks take one or more filters.

Particulate filter cartridges are disposable, and must be replaced when damaged (physically or chemically, torn or soiled with something that will damage the filter, such as many fluids), contaminated (the outside has caught dangerous particulates; for instance, infectious particles), or clogged due to accumulated particles, so that breathing resistance is too high. Particulate filters may be simple disks or other shapes of flat filter material, which are lightweight, or they may be pancake-style.

Chemical Cartridges different types of cartridges must be used to filter out different chemicals.
Most cartridges are made of activated charcoal, which has a very high surface area to absorb toxins. These carbon filters are often impregnated with reagents that react and bond with the specific airborne chemicals the cartridge targets. This process is called chemisorption; the reagents bond the toxic gases and vapors before the wearer can breathe them in. The activated carbon may be saturated with copper, zinc, silver, and molybdenum compounds, as well as with triethylenediamine. Many chemicals cannot be safely filtered out by any chemical cartridge.
Chemical cartridges must be replaced when they no longer have the ability to absorb the toxic chemicals, a point which is determined by a qualified industrial hygienist. Cartridge service life is dependent on many factors, including contaminant type and concentrations, interference from other chemicals, breathing rates, whether respirator use is continuous or intermittent, sorption capacity of the cartridges, and environmental factors like humidity and temperature.