This proposed rule would propose a determination as to whether n-propyl bromide (nPB) is an acceptable substitute for Class I and Class II ozone depleting substances used in aerosol solvent and adhesives end uses. If found acceptable, this would provide industry with another alternative to solvents with higher ozone depletion potential. An acceptability determination could include specific conditions on the use of nPB as a solvent, such as limiting the specific applications in which it may be used to those with low emissions and requiring exposure limits that would be sufficient to mitigate risk and that are consistent with industry practices. Any conditions would be for the purpose of ensuring that nPB is used in a manner that is as safe and environmentally protective as other available substitutes. OSHA has not set a specific exposure standard for nPB. If we determine that nPB cannot be used safely in a specific end use, as compared with other substitutes available for that end use, we would find it unacceptable.