UNCG Department of Environmental Health and Safety

Frequently Asked Questions

This contains frequently asked questions and sometimes mininterpreted visual signs of indoor air quality

Why is dirt coming from the ventilation system?


picture of air vent

This photo shows dust and debris impaction on a ceiling tile near an air supply diffuser. You might think the dust and debris is coming from the exhaust duct, but it is more likely the dust and dirt is already in the room. The dirt that is suspended in the air is caught by the air coming from the diffuser and impacted on the ceiling tiles due to turbulant air currents. This type of cosmetic problem can be reduced by proper housekeeping and by preventing the entrainment of particulates into the building such as keeping doors and windows closed.

Is this mold on the ceiling?


mold on ceiling?

This photo shows a water stain on a ceiling and wall from a previous water leak. This condition can provide a source of water for mold growth, but does not necessarily indicate there is mold present. Additional evaluation will need to be conducted to see if mold is growing on that surface or behind the wall. If the leak or water source is not removed, it could progress to a situation where mold growth is a problem.

Why shouldn't I block my supply vent to keep my area warmer?


picture of blocked air vent

Blocking the supply and return vents unbalances the HVAC system. You may be regulating the temperature in your immediate area, but you are also reducing the ventilation to the rest of the work environment, which could affect others in the space served by that HVAC system.

Is this mold?


picture of possible ground mold

Although it looks like mold, it could be alkaline deposits from minerals in the soil or building materials. Depending on the mineral content of the local water it could be minerals. It is very common to see what is referred to as effervesce on concrete walls and brick after those areas have been wet.

Should I use an ozone generator to clean the air in my office?


picture of a ozone generator

The US EPA has determined that ozone generators are ineffective in removing chemicals, dust, mold or other contaminants from the indoor environment. Ozone itself is considered an air containment that has a limit of 0.1 ppm. Ozone generators are not recommended for use in indoor environments.