Protection level of chemical protective clothing

Class A protective clothing refers to heavy-duty positive pressure isolation protective clothing, with its own oxygen supply system that can provide for more than one hour of breathing, and the penetration rate of common biochemical reagents within one hour is less than 0.01%. It refers to the protective clothing with the highest protective ability, air-tight protective clothing, training should be required before use, air-tightness tests should be done regularly, and cleaned after each use.
In 1990, the National Fire Protection Association (NFPA) and the American Society for Testing and Materials (ASTM) proposed and developed additional standards, which were recognized by OSHA. NFPA1991 standard e puts forward performance requirements for airtight chemical protective clothing. These requirements include chemical resistance and flame resistance testing, which can prevent 21 basic chemicals. The basic OSHA standard for chemical protective clothing requires four levels of protection.
There are four levels of A, B, C, and D. Workers at each level of danger must be equipped with corresponding levels of protective equipment and protective clothing to fully protect users.
Level A- indicates the greatest degree of danger, which can cause damage to human breathing, eyes or skin. These injuries may come from toxic vapors, gases, particles, chemical splashes, immersion or contact with toxic materials. It requires fully enclosed protective clothing, which must be equipped with SCBA or in-line breathing apparatus and appropriate accessories. Level A chemical protective clothing can also be made to comply with the NFPA1991 standard. Level B means that the environment requires the highest respiratory protection, but the requirements for skin protection are not high. It requires SCBA or a positive pressure in-line breathing apparatus with escape gas bottle, plus a hood,