Request: We received a management request for a health hazard evaluation at a dental clinic. The request stated concerns about idiopathic pulmonary fibrosis (IPF). IPF is a serious long term lung disease that can cause permanent scarring in the lungs. IPF was first identified in a cluster of dentists reported in 2018. In response to the request, we performed an air sampling survey in August 2022 to evaluate potential exposures to respirable dust, respirable crystalline silica, respirable metals, and volatile organic compounds (VOCs). We also assessed the existing ventilation systems in the dental clinic. Workplace: The dental clinic provides dental care services to patients. General dentistry services and procedures are performed at the clinic and clinic laboratory. The dental clinic is housed on the second floor of a two-story medical clinic on an academic campus. At the time of our survey, eight staff were onsite, including two dentists, two dental hygienists, three dental assistants, and one administrative staff. Our Approach We conducted a site visit in August 2022 to assess possible exposures during routine dental care, assess the ventilation systems in use, and informally interview clinic staff. We conducted opening and closing meetings with employees and management to share background information about NIOSH and this health hazard evaluation. We also described the purpose of our survey, activities that would be performed while onsite, and actions that would be taken after we concluded our survey. During our onsite survey, we: a) Collected full-shift personal air samples on dental clinic employees for respirable dust and respirable crystalline silica. b) Collected full-shift area air samples in multiple locations in the dental clinic for respirable dust, respirable crystalline silica, respirable metals, and volatile organic compounds (VOCs). c) Collected instantaneous air samples for VOCs during various tasks and procedures. d) Collected real-time measurements of respirable aerosols in and just outside of the laboratory. e) Assessed the heating, ventilation, and air-conditioning (HVAC) systems in use. f) Informally interviewed clinic staff to learn about any health concerns potentially related to exposures at work. Our Key Findings: All personal air samples were below the Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) and the American Conference of Governmental Industrial Hygienists (ACGIH®) threshold limit value (TLV®) for respirable dust. All personal air samples for respirable crystalline silica were below the NIOSH recommended exposure limit (REL) and OSHA PEL. All area air samples for respirable dust, respirable crystalline silica, and respirable metals were low; some metals were measured in all or most areas of the clinic. Some VOCs were higher in some locations or during specific tasks and procedures. Ethanol and isopropyl alcohol were the highest measurements collected during full-shift area sampling and during task or source sampling and were likely due to cleaning and disinfecting tasks. Treatment rooms (dental operatories) and staff offices did not receive adequate outdoor air from existing mechanical ventilation systems, and the clinic was unable to maintain temperatures in the clinic recommended by ASHRAE. LEV controls in the laboratory were not consistently used. When no LEV was used, higher levels of air contaminants were measured in the laboratory and adjacent hallway. Respirable aerosol generated in the laboratory migrated to adjacent areas. Employees reported no work-related symptoms. Our Recommendations: 1: Reduce risk of entrainment of air from the laboratory into adjacent spaces. 2: Encourage employees to utilize local exhaust ventilation (LEV) controls in the laboratory area during grinding, trimming, or soldering tasks. 3: Consider using LEV controls such as high-volume evacuation (HVE) and voluntarily using N95® filtering facepiece respirators (or other air-purifying particulate respirators) when performing dental procedures with nickel or silica (e.g., restorative procedures). 4: Improve ventilation so that all areas receive adequate outdoor air and maintain appropriate temperatures and comfortable humidity levels. 5: Make NIOSH-approved N95 filtering facepiece respirators (or other air-purifying particulate respirators) available for voluntary use and train employees on proper use of respiratory protection. 6: Ensure employees understand the hazards associated with working in a dental clinic and how to protect themselves. 7: Encourage employees to report any new, persistent, or worsening respiratory symptoms, particularly those with a work-related pattern, to their healthcare providers and, as instructed by their employer, to a designated individual at their workplace.