Mold Found In Home Inspections
Mold is a pervasive issue, and mold spores are commonly found in both residential and work environments. When present in significant amounts, mold can pose health risks to individuals, causing allergic reactions and respiratory problems.
Certain types of molds produce mycotoxins, which can pose serious health risks to humans and animals. “Toxic mold” refers to molds that produce mycotoxins, such as Stachybotrys chartarum. Exposure to high levels of mycotoxins can lead to neurological problems and even death. Prolonged exposure, such as daily exposure, can be particularly harmful.
Symptoms of mold exposure may include:
- Nasal and sinus congestion; runny nose
- Eye irritation; itchy, red, watery eyes
- Respiratory issues such as wheezing, difficulty breathing, and chest tightness
- Throat irritation
- Skin irritation such as a rash
- Persistent sneezing
Infants may develop respiratory symptoms as a result of exposure to Penicillium, a fungal genus. Symptoms of mold-related respiratory problems in infants include persistent cough or wheeze. Increased exposure increases the likelihood of developing respiratory symptoms during the first year of life. Studies have shown a link between the likelihood of developing asthma and exposure to Penicillium.
Mold exposure has a variety of health effects, and sensitivity to mold varies. Exposure to mold may cause throat irritation, nasal congestion, eye irritation, coughing, and sneezing, as well as skin irritation in some cases. Exposure to mold may exacerbate sensitivity, depending on the time and nature of exposure. Individuals with chronic lung diseases are at higher risk for mold allergies and will experience more severe reactions when exposed to mold. Moist indoor environments are associated with upper-respiratory-tract symptoms such as coughing and wheezing in individuals with asthma.
Causes and Growing Conditions
Molds are found everywhere and can grow on any substance when moisture is present. They reproduce by spores, which are carried through air currents. When spores land on a wet surface suitable for life, they begin to grow. Mold is often found indoors at levels that do not affect most healthy individuals.
Since common building materials can support mold growth and mold spores are ubiquitous, mold growth in an indoor environment is often related to water or moisture and may be caused by inadequate drying of flooring materials, such as concrete. Flooding, leaky roofs, building maintenance, or indoor plumbing problems can lead to indoor mold growth. Water vapor commonly condenses on surfaces cooler than the moist air, enabling mold to thrive. This moisture vapor passes through walls and ceilings, typically accumulating during the winter in climates with a long heating season. Floors over crawl spaces and basements, without vapor barriers or with dirt floors, are prone to mold. The “doormat test” detects moisture from concrete slabs without a sub-slab vapor barrier.
Significant mold growth requires moisture, a source of food, and a substrate capable of sustaining growth. Common building materials such as plywood, drywall, furring strips, carpets, and carpet padding provide food for mold. In carpet, invisible dust and cellulose are food sources. After water damage to a building, mold grows in walls and then becomes dormant until subsequent high humidity; suitable conditions reactivate mold. Mycotoxin levels are higher in buildings that have had a water incident.
Although this home experienced minor exterior damage from Hurricane Katrina, small leaks and insufficient airflow allowed mold infestation.
Mold is detectable by smell and signs of water damage on walls or ceilings and can grow in places invisible to the human eye. It may be found behind wallpaper or paneling, inside ceiling tiles, behind drywall, or under carpets or carpet padding. Piping in walls may also be a source of mold, as they may leak (causing moisture and condensation).
Spores require three things to grow into mold:
- Nutrients: Cellulose (the cell wall of green plants) is a common food for indoor spores.
- Moisture: To begin the decaying process caused by mold.
- Time: Mold growth begins from 24 hours to 10 days after the provision of growing conditions.
Mold colonies can grow inside buildings, and the chief hazard is the inhalation of mycotoxins. After a flood or major leak, mycotoxin levels are higher even after a building has dried out.
Food sources for mold in buildings include cellulose-based materials such as wood, cardboard, and the paper facing on drywall, as well as organic matter such as soap, fabrics, and dust containing skin cells. If a house has mold, the moisture may originate in the basement or crawl space, a leaking roof, or a leak in plumbing pipes. Inadequate ventilation may accelerate moisture buildup. Visible mold colonies may form where ventilation is poorest and on perimeter walls (because they are nearest the dew point).
If there are mold problems in a house only during certain times of the year, the house is probably too airtight or too drafty. Mold problems occur in airtight homes more frequently in the warmer months (when humidity is high inside the house and moisture is trapped) and occur in drafty homes more frequently in the colder months (when warm air escapes from the living area and condenses). If a house is artificially humidified during the winter, this can create conditions favorable to mold. Moving air may prevent mold from growing since it has the same drying effect as low humidity. Molds grow best in warm temperatures, between 77 and 86 °F (25 and 30 °C), although growth may occur between 32 and 95 °F (0 and 35 °C).
Removing one of the three requirements for mold reduces (or eliminates) new mold growth:
- Food for the mold spores (such as dust or dander)
- Warmth; mold generally does not grow in cold environments.
HVAC systems can produce all three requirements for mold growth. The air conditioning system creates a difference in temperature, encouraging condensation. The high rate of dusty air movement through an HVAC system may furnish sufficient food for mold. Since the cooling system is not always running, warm conditions are the final component for mold growth.
The first step in assessment is to non-intrusively determine if mold is present by visually examining the premises; visible mold helps determine the level of remediation necessary. If mold is actively growing and visibly confirmed, testing for its specific species is unnecessary.
Intrusive observation is sometimes required to assess the level of mold. This includes moving furniture, lifting (or removing) carpets, checking behind wallpaper or paneling, checking ductwork and exposing wall cavities. Detailed visual inspection and the recognition of moldy odors should be used to find problems. Efforts should focus on areas where there are signs of liquid moisture or water vapor (humidity) or where moisture problems are suspected.
The United States Environmental Protection Agency (EPA) generally does not recommend testing unless a resident of the space has symptoms. Testing should be performed by a trained professional with specific experience in mold sampling protocols, sampling methods, and the interpretation of findings. It should be done only to make a particular determination, such as airborne spore concentration or identifying a particular species. Before testing, a subsequent course of action should be determined.
In the U.S., testing and analysis should follow the recommendations of the Occupational Safety and Health Administration (OSHA), National Institute for Occupational Safety and Health (NIOSH), the EPA, and the American Industrial Hygiene Association (AIHA).
Types of tests include:
- Air: The most common form of testing to assess mold levels. Indoor and outdoor air samples are collected and their mold spore levels compared. Air testing often identifies hidden mold.
- Surface: Measures the amount of mold spores deposited on indoor surfaces, collected on tape or in dust.
- Bulk: Removal of material from the contaminated area to identify and assess the mold in the sample.
Various types of sampling are recommended by the AIHA, as each has limitations; for example, air samples will not identify a hidden mold source, and a tape sample cannot determine the level of contamination in the air.
The first step in addressing an indoor mold problem is to remove the moisture source; new mold will begin to grow on damp, porous surfaces within 24 to 48 hours. There are various ways to prevent mold growth. Some cleaning companies specialize in fabric restoration, removing mold (and mold spores) from clothing to eliminate odor and prevent further damage to garments.
The most effective way to clean mold is to use detergent solutions that physically remove mold. Many commercially available detergents marketed for mold cleanup include an EPA-approved antifungal agent.
Significant mold growth may require professional mold remediation to remove the affected building materials and eliminate the source of excess moisture. In extreme cases of mold growth in buildings, it may be more cost-effective to condemn the building rather than reduce mold to safe levels.
The goals of remediation are to remove (or clean) contaminated materials, preventing fungi (and fungi-infected dust) from entering an occupied (or non-contaminated) area while protecting workers performing the remediation.