The mold sampling method one chooses should be determined by the objective of the investigation. One may sample air or surfaces for mold contamination. The standard method for sampling air is to use a volumetric sampler e.g. RCS or Andersen N6 for viable airborne spores and hyphal fragments and Air-O-Cell, VersaTrap, Allergenco and others such cassettes for total spore counts. Testing of surfaces may involve use of RODAC agar plates for smooth surfaces, and swabs and adhesive tape on all other surfaces. It is important to note that adhesive tapes may not work well on wet and porous surfaces. Bulk samples can also be taken and plated onto agar plates or analysed by direct microscopic examination. Dust samples can be collect from surfaces such as carpets, upholstered furniture and textiles.
Media For Mold Sampling
It’s important to select media for mold sampling wisely. If one decides to collect viable air samples, the choice of media to use is very
important. Generally, malt extract agar (MEA) is used. It is a “broad spectrum” medium that supports the growth of a wide range of fungal species. However, antibiotics may have to be incorporated to surpress bacteria growth. Its main disadvantage is that fast growing molds tend to overgrow slow growers making it difficult to count colonies. To overcome this problem, DG18 and Rose Bengal can be used. These media have compounds added to them to slow down fast growing fungi and inhibit bacterial growth. If one is sampling a relatively dry environment, MEA+40% sucrose would be recommended for detecting xerophilic (dry loving) fungi.
Currently, the only reliable means for routine identification of mold species is to perform traditional mycological methods. This requires years of training and practice. Be sure to use a lab that has a qualified Mycologist on-board (preferably at PhD level). The lab should also be regularly participating in a recognised proficiency testing program such as the AIHA EMPAT program.
Performing Effective Mold Sampling
If you need to take mold samples, use properly trained personnel or to get yourself trained. If you decide to undergo training, select a mold training course that provides skills and background information to enable you recognize indoor mold, develop effective mold sampling strategies, and interpret laboratory results.