Most regulations require initial testing followed by periodic retesting every 2-5 years, depending on facility type and occupancy. Schools typically test every 5 years, while healthcare facilities may require more frequent testing. New construction, renovations, or changes in building use patterns may trigger additional testing requirements. Facilities with previous high readings need ongoing monitoring to ensure mitigation systems remain effective. Property managers should establish regular testing schedules to maintain compliance, protect occupants, and avoid liability issues. Professional testing providers can develop customized monitoring programs that meet regulatory requirements while minimizing disruption to operations.