Advocacy Adviser

Dealing with mold in HVAC systems

Environmental health and safety director discusses the essentials of routine maintenance to keep HVAC systems spore-free
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Microbial growth such as mold can be costly to remediate, unhealthy to the building occupants and damaging to the hospital’s reputation. 

Airborne mold spores are constantly present in outdoor concentrations and vary widely by season, location and even time of day. The spores can enter the building through the ventilation system, open windows and doors, and through air leaks in the building envelope. Mold can grow on virtually any substance if moisture or water, oxygen and an organic source are present. 

HVAC systems play a very important role in hospitals by maintaining not only a comfortable environment of care but also a clean environment of care. HVAC systems also can be a known contributor to moisture and microbial growth because water is a natural byproduct. Small amounts of wetting and drying are normal and don’t present a long-term risk for mold growth if drying occurs immediately after wetting. This is one reason it is critical to have a properly designed and well-maintained HVAC system. 

Routine maintenance is essential in preventing microbial growth. Access doors, panels or other means should be provided in ventilation equipment, ductwork and plenums to allow for convenient and unobstructed access for inspection, cleaning and routine maintenance of air intakes, coils, drain pans, fans and humidifiers. It is far too common to see standing water in drain pans due to clogged condensate lines, drain pans that are not sloped or drain line connections placed too high above the drain pan’s floor. 

When it comes to operations and maintenance, ASHRAE Standard 62.1, Ventilation for Acceptable Indoor Air Quality, Table 8-1, contains the minimum activity and frequency for ventilation system equipment and associated components. Effective filtration is one of the most important factors in preventing dirt and debris from accumulating in the HVAC system. In addition, ultraviolet lamps and regular cleaning are added measures that can help keep coils free from buildup and prevent mold growth on coils. 

The environment of care is supposed to be a safe and healthy environment, which is why it is critical to perform routine maintenance of HVAC systems.