OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at http://www.osha.gov.September 20, 2017MEMORANDUM FOR:REGIONAL ADMINISTRATORSFROM:THOMAS GALASSIActing Deputy Assistant SecretarySUBJECTLaunch of Enforcement of the Respirable Crystalline Silica in Construction Standard, 29 CFR § 1926.1153The Respirable Crystalline Silica construction standard, 29 CFR § 1926.1153, becomes enforceable on September 23, 2017. The standard establishes a new 8-hour time-weighted average (TWA) Permissible Exposure Limit (PEL) of 50 µg/m3, an action level (AL) of 25 µg/m3, and a host of ancillary requirements.During the first 30 days of enforcement, OSHA will carefully evaluate good faith efforts taken by employers in their attempts to meet the new construction silica standard. OSHA will render compliance assistance and outreach to assure that covered employers are fully and properly complying with its requirements. Given the novelty of the Table 1 approach, OSHA will pay particular attention to assisting employers in fully and properly implementing the controls in the table. OSHA will assist employers who are making good faith efforts to meet the new requirements to assure understanding and compliance.If, upon inspection, it appears an employer is not making any efforts to comply, OSHA's inspection will not only include collection of exposure air monitoring performed in accordance with Agency procedures, but those employers may also be considered for citation. Any proposed citations related to inspections conducted in this time period will require National Office review.To ensure effective implementation of the new standard, OSHA has developed interim inspection and citation guidance to be released prior to termination of this memorandum. The compliance directive will be finalized thereafter.Regional offices are advised to contact the Office of Health Enforcement at 202-693-2190 with questions regarding enforcement of the new silica rule.