Why does the standard require employers to use supplied air respirators?
A. The standard requires supplied air respirators because methylene chloride breaks through the chemical cartridges and canisters used on air purifying respirators in too short a time for these respirators to provide reliable protection. Moreover, methylene chloride provides inadequate warning of when it breaks through chemical cartridges and canisters because the odor threshold concentration level is higher than the PEL values. Q. May employers use the controlled negative pressure (CNP) method or the ambient aerosol method for quantitative fit testing of respirators? A. These instruments are permitted for quantitative fit testing. Protocols for their use are contained in Appendix A of the revised respiratory protection standard (29 CFR 1910.134) that was published in the Federal Register on January 8, 1998. Medical Surveillance Q. What action must employers take to comply with 29 CFR 1910.1052(j)(1)(iii), which requires employers to make medical surveillance available to employees who
