What practices would you recommend for sampling for hazardous drugs within and around the engineering control?

To my knowledge, there is no good guidance establishing acceptable levels of surface contamination of hazardous drugs. Testing for these drugs is expensive and time consuming. Based on the literature, if you are handling hazardous drugs, you can expect to find contamination on multiple surfaces and in multiple areas of the pharmacy. The key for preventing contamination is to follow good work practices as offered in the NIOSH Alert: Preventing Occupational Exposures to Antineoplastic and Other Hazardous Drugs in Health Care Settings.