**Note: Sampling should always be performed by a qualified professional. Inappropriate sampling methods can severely misrepresent the actual environment. Thus, Fungal analysis and reports should only be performed and interpreted by a qualified professional.

Activity levels

The activity level of a particular environment at the time of sampling will almost certainly affect the data collected. Indoor spore levels can range from below 5% to 100% (or more) of that measured outdoor at the time sampling was performed. These figures should be regarded as very general guidelines, only. The major contributing factor is the accessibility of outdoor air to the indoor environment. Meaning, a residence with open doors and windows or heavy foot traffic may reach 90% (or higher) of the outdoor level and buildings with little air exchange reporting 5% or less. In addition, excessively soiled or damaged interiors can exceed 100% of the outdoor levels to some degree.

The use of aggressive or improper sampling methods typically increase the number of spores found on a sample. While this may present indications of past fungal activity by agitating sources of indoor spores, aggressive sampling magnifies interpretation problems, making the comparison of an aggressive or improper sample meaningless.


Rain washes the air clean of many spore types while it assists in the dispersion of others. Sampling on rainy, foggy, or very humid days may result in outdoor counts which have a significantly different distribution of spores. Generally, rainy day microflora differs from that of dry, sunny microflora.

Sampling on days with strong winds also creates problems. High outdoor counts may mask indoor mold problems since the interpretation is made on the basis of a ratio of indoor to outdoor spore counts.

Condition of the area sampled

The value of field observations in the assessment of indoor air quality complaints cannot be overstated. Laboratory results present only one (very small) aspect of the entire picture. The use of a qualified Indoor Environmental Expert (IEP) can not be overstated. An effective evaluation needs to take into account the condition of the area or building in question. Potential field considerations include:

  • General cleanliness of the area.
  • Doors and window positions.
  • Condition of the HVAC system.
  • Indoor source of water or high relative humidity?