CONSTRUCTION DUST – A STEALTH IRRITANT
Often overlooked, but frequently present, construction dust, which generally is identified as “calcite grains” or “gypsum grains,” can often be found as a factor in complaints concerning indoor air quality. Remodeling or rebuilding and refinishing walls in an office or home will produce this fine grey/white and powdery particulate by sanding to smooth out irregularities in walls and ceilings.
Construction dust is routinely detected in settled dust samples that are analyzed for composition. When this material is found in relatively high percentage of the dust sample it becomes a suspect for certain symptoms. This is of particular interest when symptoms reported are irritation to eyes, skin and respiratory system. These symptoms are usually, at least initially attributed to the suspected presence of airborne fiberglass. When fiberglass contamination is not detected in significant quantities, the next likely offender is construction dust.
Construction dust contamination occurs due to improper containment of construction dust and debris during construction activities. Often attempted isolation of construction activities consists of taping up a flimsy plastic sheet like the cheapest “paint drop cloths” sold in many home improvement stores. If this is done at all, it has only minimal effect on containment of construction dust. This material does usually get cleaned up after the construction project has been completed, but can remain in place for long periods of time in locations that are out of sight and seldom if ever cleaned.
Other dust collecting locations include some light fixtures and pictures or other items that are hung on walls.
Some of this construction dust that has become settled on surfaces can become airborne due to occupant activities and air movement from HVAC systems.
Airborne construction dust as well as just general airborne dust can accumulate in fabric covered chairs and other porous materials, including carpets and partitions. Sitting down in chairs with high dust content can routinely produce an invisible dust cloud, much of which is inhaled by the person occupying the chair and others in close proximity.
HVAC systems are often run during construction activities, thereby contaminating the system and potentially exposing occupants in the entire area served by that system.
One logical action to take to prevent or lessen construction dust contamination is simply to ensure that construction areas are properly contained so that the dust is not spread to other parts of the building. A second action is if HVAC systems must be run during construction periods ensure the return vents are covered to prevent contaminated air from entering the airstream. There must also be allowance for exhausting the air inside the containment area so that the construction area is not positively pressurized thereby forcing contaminated air to other parts of the building. Of course the air must be exhausted to somewhere that it is not going to create a contamination problem there.
Once the construction has been completed and general cleanup has been done, it would be prudent to environmentally deep clean the area. This consists of a thorough vacuuming of all surfaces (floors, walls and contents) using HEPA (High Efficiency Particulate Air) filtered vacuums. Vacuuming should be followed by a wipe down of hard dust collecting surfaces (not electrical or fabric) with damp cloths.
When HVAC systems are found to be contaminated with construction dust the only option is to have them thoroughly cleaned to National Air Duct Cleaners Association (NADCA) standards including sanitizing the coils with an EPA registered product such as Oxine. Environmental deep cleaning of the area served should follow immediately after the HVAC cleaning.