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Interpreting Indoor Air Quality Results

Air sampling is considered the highest level of scientific confirmation as it not only confirms the presence of mold spores and types, it also indicates the quantified amount of mold spores in the air. This information can then be interpreted to understand the potential impact to health as mold spores caught in the air can be inhaled into the lungs. Mold spores found in the air are typically viable, meaning if conditions are favorable, they are able to grow.

Air sampling must be compared to an exterior control sample. An exterior control is compared to interior samples for elevations in spore types and or the presence of spore types absent in the exterior. The results of this comparison can be used to assist in identifying if an active fungal growth or indoor reservoir exists.

  • 0-50 spores – These are trace levels of mold concentration and are typically not an issue. Considered extremely clean. Stachybotrys and Memnoniella can be considered elevated at this level and any level above this point.

  • 51-500 spores – Very low levels of mold concentration. Still considered extremely clean.
  • 501-1500 spores – Low levels of mold concentration. Considered acceptably clean. Penicillium/Aspergillus & Cladosporium spore concentrations can be found at this level and can be normal. This mold concentration level does not necessarily require remediation. Normal cleaning and wiping of surfaces can help to reduce spore concentrations below this level.

  • 1501-3000 spores – Slightly elevated levels of mold concentration. Spore concentrations at this level may indicate an indoor reservoir exists. Exterior control results must be compared to indoor samples to identify if cross contamination from the exterior is playing a role. If water or moisture intrusion or visual mold contamination is not found during the assessment, hyphal fragment concentration >100/m3 will help confirm likelihood of a nearby active fungal growth. These levels can be caused by a dusty home or lack of upkeep. Normal cleaning and wiping of surfaces can help to reduce spore concentrations below this level.

  • 3,001-4,500 spores – Moderate levels of mold concentration. Unless there is a corresponding concentration in the exterior control, this is the level where some form of cleanup may be required. If visual mold contamination is identified, then cleanup of that area is required. If water or moisture intrusion or visual mold contamination is not found during the assessment, hyphal fragment concentration >100/m3 will help confirm likelihood of a nearby active fungal growth. These levels can be caused by a very dusty home or extreme lack of upkeep. Vigorous cleaning and wiping of surfaces and an increase in ventilation can help to reduce spore concentrations below this level. If the area is relatively clean, a hidden fungal growth may exists. Mold mapping techniques can be used to identify the location of a hidden fungal growth. Most people with normal immune function can tolerate this level, however, severely sensitive people may experience symptoms during prolonged exposure.

  • 4,501-10,000 spores – Moderate to high levels of mold concentration. Unless there is a corresponding concentration in the exterior control, this is the level where cleanup is typically required. If visual mold contamination is identified, then cleanup of that area is required. If water or moisture intrusion or visual mold contamination is not found during the assessment, hyphal fragment concentration >100/m3 will help confirm likelihood of a nearby active fungal growth. These levels can be caused by a very dusty home or extreme lack of upkeep and lack of ventilation to the area. Vigorous cleaning and wiping of surfaces, increase in ventilation and fungal fogging can help to reduce spore concentrations below this level. If the area is relatively clean, a hidden fungal growth most likely exists. Mold mapping techniques can be used to identify the location of a hidden fungal growth. Relative humidity may be elevated above 60%. This is the level where some people with normal immune function may experience symptoms during prolonged exposure.

  • 10,001-25,000 spores – High levels of mold concentration. Unless there is a corresponding concentration in the exterior control, this is the level where some form of cleanup is required. Hyphal fragment concentration will be elevated above 100/m3. Fungal growth size can range from >10sf and larger. If visual mold contamination is identified, then cleanup of that area is required. If water or moisture intrusion or visual mold contamination is not found during the assessment, a hidden fungal growth is near. Mold mapping techniques can be used to identify the location of a hidden fungal growth. Relative humidity may be elevated above 60%. This is the level where most people with normal immune function will experience some form of symptoms during prolonged exposure. Restrictions to these areas may be implemented.

  • 25,001-75,000 spores – Very high levels of mold concentration. Cleanup will be required and most likely requires a Professional Mold Remediator. Hyphal fragment concentration will be elevated above 100/m3. Fungal growth size is typically >100sf. Relative humidity is typically elevated above 60%. This is the level where nearly all people with normal immune function will experience symptoms during prolonged exposure. Restrictions to these areas may be implemented.

  • 75,000-1,000,000+ spores – Extremely high levels of mold concentration. Professional Mold Remediator will be required. Hyphal fragment concentration will be extremely elevated. Fungal growth size is >100sf. Relative humidity will be elevated above 60%. Mold exposure at this level is considered hazardous for human occupancy, vacate the area.