This standard has many requirements, all of which must be implemented by an employer who wants to use respirators to control worker exposures. Management almost never implements all pieces of the OSHA standard. They are, therefore, technically in noncompliance with the law. A detailed and specific knowledge of the standard by unionists can allow the union to fight effectively management's attempt to use respirators. Respirators don't stop absorption through the skin.
Many chemicals affect the skin directly.
Others pass right through the skin to cause damage inside the body. Since respirators only limit what you are inhaling, they are essentially useless where skin contact continues. If the chemical does not have such warning properties, then the law says you are not permitted to wear a respirator. If it leaked through the respirator and exceeded the OSHA level of 50 ppm you would never know it. Respirators should not be used as protection against cancer-causing agents because there is no safe exposure level for these chemicals.