LEED projects require air quality testing at multiple phases to earn maximum points and ensure ongoing performance. Pre-occupancy testing should be conducted after construction completion but before tenant move-in to verify that indoor air meets health standards. Ongoing monitoring may be required for certain credits to demonstrate sustained performance over time. Testing should also be conducted after any major renovations or changes in building systems that could affect indoor air quality. Professional testing timing must align with LEED requirements and building occupancy schedules to provide valid documentation for certification submission.