A NIOSH B Reader is a physician (typically a radiologist or pulmonologist) certified by the National Institute for Occupational Safety and Health to interpret and classify chest radiographs for pneumoconioses — lung diseases caused by inhaled mineral dust such as silica, asbestos, and coal dust — using the International Labour Office (ILO) classification system. Certification requires passing a rigorous 6-hour proficiency examination; recertification is required every 4 years to remain on the active roster. B Reader interpretation is required by several OSHA medical surveillance standards, including the Respirable Crystalline Silica standard (29 CFR 1910.1053), the Asbestos standard (29 CFR 1910.1001), and the Coal Mine Safety and Health Act. For occupational-health clinics that serve mining, construction, abatement, or foundry employers, the choice is to staff (or contract with) a B Reader or to send mandated chest X-rays out for classification — a workflow and cost decision that materially affects program viability.