In this episode, Dennis Pivin talks with Dr. Mark Knight from the University of Waterloo about photoionization detectors (PIDs) and their role in monitoring styrene levels during cured-in-place pipe (CIPP) installations. They revisit a landmark study on styrene migration in laterals and explain how PIDs should be properly calibrated and interpreted. The discussion clarifies common misconceptions about VOC readings and highlights the importance of understanding your instrument and its limits when assessing exposure risks on job sites.