Evaluation of Spirometry for Medical Clearance in Occupations Requiring Respirator Usage

Medical certification of workers for respirator use is an important activity of occupational medicine health professionals. Spirometry is a diagnostic tool to evaluate respiratory distress/insufficiency that may affect respirator use. The pulmonary function data of 337 subjects from different occupations that required medical evaluation to wear a respirator were analyzed to determine the effect of using various spirometric equations on respirator fitness outcomes. Of 337 subjects who were cleared for respiratory use by medical questionnaires for respirator compliance, 14 (4.15%) failed to pass respirator compliance by NFPA criteria and 5 (1.48%) failed to pass respirator compliance measures by ATS criteria. We compared the use of different spirometric equations to evaluate these measures, and it was determined that the Crapo equation cleared more workers for respirator use as compared to the Knudson and NHANES III equations. As some workers were able to qualify for respirator use based on questionnaire alone but failed respirator clearance after pulmonary function testing, it is recommended that spirometry is used to evaluate clearance for all workers who will use a respirator in the workplace. As well, using different spirometric equations can affect the outcome on passing or failing clearance for respirator use, and this should be considered in a respiratory medical certification program.