First, let’s explore why mold exists. In nature, plant and animal debris are degraded to their most simple chemical components by fungi (mold). A mold is any of the various fungi that often cause disintegration of organic matter. Along with soil bacteria, they can be considered the “garbage men of nature”. Without their activity, the recycling of organic material would cease to exist and the earth’s surface would remain covered in refuse.

Temperature: Fungi are not able to control their own temperature, so they must grow at the temperature of its environment. Most fungi grow in temperatures preferable to humans, therefore it is difficult to control fungi (mold) growth by use of temperature controls, especially in environments inhabited by humans.

Food Source: Unlike plants, fungi (molds) do not make its own food and do not require light for normal growth. Molds use extracellular (outside their cell body) digestion to consume organic materials such as paper, wood, carpet, and drywall. Organic materials can be found throughout most buildings so it is difficult to control fungi growth by limiting food sources.

Moisture: Similar to humans, fungi (molds) are made up of mostly water. Most molds thrive in environments with a relative humidity of 70% or higher. After the source of excess moisture has stopped, the mold hasn’t necessarily stopped growing. Various surfaces may remain saturated with water for weeks if not properly dried. The longer the water remains, the higher the potential for mold contamination.

Time: Mold also requires oxygen for growth and prefers areas with low levels of ultra-violet light, hence mold grows well in dark, damp areas that provide a food source and plenty of oxygen. In some cases, it can take as little as 24 hours for the growth process to begin.

Contamination: Mold grows or colonizes on its food source and releases spores in order to reproduce. Indoor airborne spores may land on surfaces with the required temperature, food source, and moisture, causing mold growth to occur. Typically, mold spores are anywhere from 2 to 100 microns in size and are easily inhaled.

Health Effects: There are over 100,000 known species of molds on the earth, of which about three dozen cause health problems in humans. The adverse health effects caused by fungi (mold) varies due to the numerous species, the types of allergens, metabolites and toxins they produce in different environments and the different susceptibility of humans who are exposed to these bioaerosols (airborne biological organisms). Living fungi (mold) can be infectious agents, causing Aspergillosis in immunocompromised patients, or Coccidiomyces in a worker cleaning out a bird-infested attic. The gases released by the metabolic processes of mold (microbial volatile organic compounds known as mVOC’s) can cause irritation to mucous membranes resembling an intense allergic reaction. Cell wall components, including betaglucans and mycotoxins can also cause reactions even if the fungus (mold spore) is dead. Therefore, remediation of impacted areas with a biocide may not reduce health complaints, as these components may still remain in the air, although they are non-viable.

Lead has many different uses. It is used in the production of batteries, ammunition, metal products (solder and pipes), and devices to shield X-rays. Because of health concerns, lead from gasoline, paints and ceramic products, caulking, and pipe solder has been dramatically reduced in recent years. Lead can affect almost every organ and system in your body. The most sensitive is the central nervous system, particularly in children. Lead also damages kidneys and the reproductive system. The effects are the same whether it is breathed or swallowed.

Small children can be exposed by eating lead-based paint chips, chewing on objects painted with lead-based paint, or swallowing house dust or soil that contains lead. Even at much lower levels of exposure, lead can affect a child's mental and physical growth.

Bacteria metabolize carbon compounds (biological material) in the presence or absence of oxygen, as opposed to molds breaking down materials by use of oxygen. Examples of bacteria harmful to humans: E. Coli, Salmonella, Bacillus anthracis “Anthrax”, Legionella pneumophila causing “Legionnaires disease”, Mycobacterium Tuberculosis causing “TB”.

*In general, indoor air has a higher concentration and more species of bacteria than outdoor air.

*Most naturally occurring bacteria do not cause human illness.

Viruses invade cells and inject their genetic code into host cells and teach it to reproduce viruses. Viruses are considered to be the smallest biological contaminant on earth and need a host to reproduce. Examples of viral bioaerosols (viruses) which infect humans and are transmitted by air are influenza A & B, measles, mumps, and chicken pox. Other examples are: polio, rabies, HIV, SARS, Hepatitis, ebola, and the common cold. Respiratory diseases are most often caused by viruses.

Protozoa are usually found indoors growing in water reservoirs. They feed on algae, bacteria, and other microorganisms. A few protozoa can cause severe infections, but most produce either antigenic or toxic metabolic products which aerosolize and may contribute to syndromes such as hypersensitivity pneumonitis and humidifier fever. The protozoa disease Malaria is estimated to have caused the most deaths in history.

Volatile Organic Compounds are gases emitted into the air from cigarette smoking, building materials, paints, adhesives, dyes, solvents, caulks, cleaners, deodorizers, hygiene products, waxes, pesticides and other sources. New homes or buildings often receive occupant complaints of irritation and physical discomfort that relate to VOC sensitization from products that “off gas” after installation. A few examples of VOC’s are: Formaldehyde, Acetone, Ethanol, Benzene, Toluene, and Styrene

Allergens are any substance that can cause an acute allergic reaction or a continued allergic response for an extended amount of time. Examples are Pollen, Animal Allergy (dander, saliva, urine, feces, hair, feathers), Dust Mites (excrement is an allergen), and Cockroach (feces, saliva, eggs, shed body cuticles). Allergic exposure can cause diseases such as Allergic rhinitis/sinusitis, Allergic asthma, Allergic contact dermatitis, and Hypersensitivity pneumonitis.