Air sampling is one of the tools used in mold investigation. The primary objective of mold investigation is to determine the extent of mold growth and subsequently its potential effect on indoor air quality. Air sampling helps to termine whether or not visible mold growth has degraded indoor air quality. It may also help to detect the presence of hidden mold growth. Some investigators use air sampling to determine the effectiveness of remediation. This is achieved by taking air samples before and after remediation.
Interpretation of Air Sample Results
Interpretation of air sample results can at times be very difficult. However, having a clear objective, prior to air sampling can make results interpretation easy.
As often stated, fungal spores are present in virtually all environments including indoors. Therefore, presence of some fungal spores indoors is considered normal. Generally, for well maintained mechanically ventilated buildings, airborne spores should be qualitatively similar but quantitatively lower than the outdoors. For naturally ventilated buildings, the airborne spore concentration and their diversity in the indoor air is similar to that of outdoor air.
For both mechanically and naturally ventilated buildings, presence of airborne spores of molds usually found in indoors, in numbers significantly higher than those of outdoors, is an indication of indoors sources of mold growth.
Interpretation of air samples collected primarily to determine whether there was mold growth indoors is therefore based on a comparison of concentrations and categories of spores in outdoor and indoor samples. Significant counts of species present indoors and absent (or in lower counts) outdoors suggest the source for those species is indoors. In the absence of any visible mold growth, further investigation would be required to determine the source and extent of any hidden mold growth.
It’s important to note that the conclusion derived from air sample results should always be backed by visual inspection and the building history.