If you can see or smell mold that it should be cleaned up and the source of the moisture be identified and corrected.

The U.S. Environmental Protection Agency advises states this and that “it is clearly prudent to avoid mold exposure” and the Center for Disease Control has indicated that a building with mold may be unhealthy. Medical science has identified specific molds, which are capable of causing allergy symptoms and other illnesses. There are currently no regulations in regards to allowable spore count exposure because small amounts may cause illness in some people and others who are less susceptible may not become ill from larger amounts.

Evaluation Criteria for Indoor Mold Spore Levels

Most of the molds found are generally categorized as Allergen Molds and are capable of causing any of the usual allergy symptoms, such as rhinitis, hay fever type symptoms, sinusitis, extrinsic asthma, edema, bronchospasm, pulmonary emphysema, hypersensitivity, skin infections, and eczema in susceptible individuals.

Air Sampling Methods

Air samples are possibly the most common type of environmental sample that investigators collect to study bioaerosols (mold, pollen, particulates). The physics of removing particles from the air and the general principles of good sample collection apply to all airborne materials, whether biological or other origin. Therefore, many of the basic principles investigators use to identify and quantify other airborne particulate matter can be adapter to bioaerosol sampling.

In addition to being major Allergenic molds, some strains are considered to be potentially toxic and may cause non-allergic respiratory symptoms; exposure may cause other serious health effects. Although these molds are commonly found indoors and outdoors around the world, the levels indoors should be similar to or less than the outdoor levels.

Mycotoxin Testing

Mycotoxins are toxic, secondary metabolites produced by fungi. Their affects on people will vary based upon specific mycotoxin exposure, doses, sensitivities, and routes of exposure, including inhalation, dermal contact, or ingestion. However, symptoms that have been associated with mold exposures have included idiopathic pulmonary hemosiderosis in infants, cytotoxicity, cognitive impairment, enxephalopathies, immunosuppression, and others.

Outside Control

Principle: An outdoor sample of the same volume is taken on the same medium type to serve for comparison with the results of inside sample readings. If the numbers and types of any organisms recovered inside significantly exceed those found outdoors, a condition of fungal amplification is then confirmed as occurring with in the building.

Inside Control Sample

Indoor control samples are taken in area(s) located apart from the known water damaged or mold infected areas. The results of these sample(s) are used to establish what a typical indoor ecology would be at time of testing. These results would be compared to the findings in the damaged area(s).

Swab Sampling Methods

Surface sampling of the “suspect growth” will allow the lab to culture the microbial (mold, yeast, bacteria) as a viable micro-organism calculating CFU/IN2 (Colony Forming Units per sq. in.). These viable colonies produce spores that can be identified by genus and individual species allowing classification of the micro-organism as allergenic, mycotoxic, pathogenic, or other health concern.

Particle Impactor Sampling — Viable Mold And Bacteria Analysis

This method of air sampling involves drawing a measured volume of air over culture media in Petri dishes. These dishes are incubated in a certified microbiological laboratory so the organisms impacted on the plate can grow. The fungi or bacteria are counted and identified by genus and species.


  1. Fungal cultures can determine whether spores are viable (alive) and allows for specific identification by species.
  2. Bacterial cultures provide enumeration and identification of viable bacteria present in the air.

From these culture results, airborne concentrations of viable microbial spores can be projected indicating CFU/M3 (Colony Forming Units per cubic meter of air).


Bacterial like fungi are very common in soils, water, house plants, etc. They can quickly grow and accumulate in water such as humidifier reservoirs, AC condensate pans and in carpets that remain moist over extended time periods.

The basic procedure is to differentiate bacteria into two (2) large groups is called “grain stain”. A large number of environmental bacteria are grain negative. Grain negative bacteria are known to produce endotoxins (also known as Pyrogens or fever inducers). Many grain negative bacteria are waterborne, associated with foods, vegetables, in soil and found in air. Detection of pathogenic or opportunistic bacteria where immune-compromised people reside may not be acceptable.

Reference: P & K Microbiology Services, lnc. – 1996

Reference Information:
Gram Negative Rod Bacteria

Gram negative bacteria are known to produce endotoxins (atso known as Pyrogens or fever inducers) that can be ingested or inhaled when present in the environment. Many gram negative bacteria are waterborne, associated with foods, on vegetables, in soil and found in air. Bacteria, like fungi, are very common, can quickly grow and accumulate in water or continually moist host materials. A normal environmental system will have an assortment of different bacteria types, none of which will be predominant. High levels of one type of bacteria, especially gram-negative rods, are considered significant.


Microorganisms are a normal and essential component of all environments. Bacteria and fungi are needed to break down complex molecules found in organic matter. If provided with water and a food source, they will colonize almost any area on Earth.

It is normal to find some quantity of microorganisms in indoor air. In a normal indoor environment, their numbers should be significantly less than outdoor levels. Excessive moisture inside a building from leaks, floods, or other sources can create an “out-of-balance” environment that will tend to amplify their population. Depending on the amount of water, temperature, lighting, and food available, differing species may become dominant. In consequence, the presence of some microorganisms in large quantities may lead to adverse health effects involving building occupants.

Adverse health effects in affected individuals can include both illnesses and allergic responses. Symptoms may range from headache, malaise, and muscle pain to shortness of breath and fever. These effects may be the result of contact with the microbes or spores themselves, or with contracting the airborne toxins that may excrete. Test results and health concerns should be shared with your physician for the best and most accurate interpretation.

Schedule a Consultation

AIAQS will inspect any Residential, Commercial, lnstitutional or Healthcare property to find and identify excessive and ongoing moisture conditions that support microbial growth. This includes the HVAC systems. Validation testing will be performed to identify Allergenic and Pathogenic mold types including the airborne or surface level concentrations. Comparison to existing standards and Guidelines will be defined.