Indoor Environmental Air Quality


Fan Coil Units

The two main types of fan coil units found in residence halls are units mounted on the wall and units mounted below the window. It is important when arranging your room that you keep the air intakes and discharges unobstructed for the units to work properly. Due to the large volume of air circulating through these units, it is common for dirt/dust to accumulate on the metal diffusers associated with the air intakes and air discharges. Surface sampling by an environmental consultant has found that this dirt/dust contains mold types that are common to the outdoor environment, but that the metal diffusers themselves are not capable of supporting mold growth.

 Upright Wall Unit

The upright wall-mounted unit in the photo above is shown after servicing with a new filter installed. The heating/cooling coil is located behind the filter.


Under Window mount

Window mounted unit in the photo above is shown prior to servicing with the dirty filter still in place. Although dirty filters do not pose a health hazard, they do put more strain on the fan system and can reduce airflow. You can help reduce the amount of loading on the air filters by regularly cleaning your room. The discoloration in the drip pan is associated with mineral deposits and the use of treatment tablets and is not a health hazard.

Although it is less common, some dormitory rooms are cooled using window air conditioners like the one in the photograph below:

In Window Unit

The air filters on these units are made of a metal mesh and are designed to be cleaned and reused, however these units are not designed to be fully disassembled for cleaning.  Although the units are cleaned at the beginning of the school year, it is common for dirt/dust to collect on surfaces that are directly in the air flow. This includes the air intake grill, air filter, Styrofoam plenum, and air discharge grill.

In window

The above photograph shows a relatively minor build-up of dirt and dust on the air discharge diffuser and Styrofoam plenum. Air and dust sampling conducted by a third-party consultant on uncleaned units consistently showed that dirt/dust samples contained mold spores that are commonly found in outdoor air.  In addition, air samples taken indoors showed much lower concentrations of mold than that found outdoors.



If you have questions about how an investigation is completed, please see the "How Does the University Investigate Mold Concerns?" page.

Additional resources:

CDC's Main Page on Mold:

CDC’s Mold Testing page:

CDC's Indoor Air Quality Page:

EPA’s Mold Testing and Sampling page:

EPA's Main Page on Mold: