Micro-organisms can grow on the damp filter of an HVAC system.

Micro-organisms, such as mold, bacteria, and other fungi, can indeed thrive on damp surfaces, including the filters of HVAC systems. When humidity levels are high or when moisture accumulates on the filter due to condensation or lack of adequate airflow, it creates a favorable environment for these organisms to grow. The organic materials that can also be present on or around the filter, such as dust, pollen, and debris, serve as nutrients, further promoting microbial growth.

Understanding this is crucial for mold inspectors and HVAC professionals, as it highlights the importance of regular maintenance and filter replacement in HVAC systems. Maintaining a dry environment and ensuring proper airflow are essential practices to prevent the growth of harmful micro-organisms, which can affect both the air quality in buildings and the health of occupants.

The other options do not reflect the reality of HVAC systems. While micro-organisms may predominantly be found on the filter surface, they can also penetrate deeper into the filter material if conditions allow. The assertion that micro-organisms cannot grow on HVAC components is false; they can grow on various parts of the system if moisture is present. Regular inspections and maintenance can mitigate such risks effectively.