OSHA requirements are set by statute, standards and regulations. OSHA's interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. These letters constitute OSHA's interpretation of the requirements discussed. Note that OSHA's enforcement guidance may be affected by changes to OSHA rules. Also, from time to time OSHA updates their guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at http://www.osha.gov/.