Breeze Through 2025 CSMI Exam – Master Indoor Air Science with Confidence!

The recommended action for Category 3 ductboard according to the IICRC S520 is to remove and replace it. Category 3 is classified as unsanitary, containing materials that may have been contaminated with harmful microorganisms, sewage, or other waste materials. Such contamination poses significant health risks and often cannot be effectively remedied through cleaning methods such as HEPA vacuuming, damp wiping, or leaving the material in place.

Additionally, due to the porous nature of ductboard, removal and replacement are necessary to ensure that contaminants do not remain embedded in the material, which could lead to ongoing indoor air quality issues and potential exposure to hazardous substances. This approach aligns with the best practices for maintaining a safe and healthy indoor environment, emphasizing that when contamination is severe, the only viable solution is to eliminate the source altogether.