Molds are types of fungi found throughout the natural environment. Molds reproduce by generating tiny, microscopic spores, just like how plants reproduce by producing seeds.
Mold spores can be found in both indoor and outdoor air, as well as settled on indoor and outdoor surfaces. In the outdoors, molds live in the soil, on plants, and on dead or decaying organic matter. They play an important and natural role in the breakdown of leaves, wood, and other plant debris.
However, when molds grow indoors, they can damage building materials, furnishings, clothes, and other organic materials. They can also cause respiratory and other health problems for building occupants.
Molds can grow on virtually any substance, as long as moisture and oxygen are present. There are molds that can grow on wood, paper, carpet, foods, and insulation.
Molds need three things to grow:
10 Things to Remember about Mold:
Essential Readings and Useful Links on Mold:
Health Effects of Mold Exposure
Exposure to molds does not always cause health problems. However, some people are sensitive to molds and are at risk for potential negative health effects. Public safety is the most important reason to prevent mold growth and to address any existing indoor mold.
Health effects from exposure to mold vary greatly depending on the person and the amount of mold present.
Symptoms may include coughing, wheezing, and nasal and throat conditions. People with asthma or allergies who are sensitive to mold may notice their asthma or allergy symptoms worsen. Individuals with severely weakened immune systems who are exposed to mold are at risk of developing serious fungal respiratory infections.
Individuals that may be particularly sensitive to mold include:
It is important to consult a medical professional if you are concerned about the potential health effects of mold exposure.
Recent media reports have popularized the term "toxic mold." According to the Center for Disease Control and Prevention, the term "toxic mold" is not accurate. While certain molds are toxigenic, meaning they can produce toxins (specifically mycotoxins), the molds themselves are not toxic or poisonous.
There are very few reports that toxigenic molds found inside homes can cause unique or rare health conditions, and a causal link between the presence of the toxigenic mold and these conditions has not been proven. Hazards presented by molds that may produce mycotoxins should be considered the same as other common molds, and efforts should be made to prevent the growth of all types of molds.
Molds need both food and water to survive; since molds can digest most things, water is the factor that limits mold growth. Molds will often grow in damp or wet areas indoors.
Moisture control is the key to mold control.
Common sites for indoor mold growth include areas where water and humidity may be present, including:
Mold and Building Materials
Many building materials contain the nutrients necessary for mold growth. Wet cellulose (plant material) materials, including paper and paper products, cardboard, ceiling tiles, wood, and wood products, are particularly conducive for mold growth, as are drywall, carpet, fabric, and upholstery.
Common sources or causes of water or moisture problems include:
Uncontrolled humidity can also be a source of moisture leading to mold growth, particularly in hot, humid climates. Recent changes to building codes have included increased emphasis on making sure buildings are tightly sealed to conserve energy. It is important that tightly sealed buildings also have adequate ventilation systems to ensure a sufficient quantity of fresh air is introduced into the occupied space, and that humidity levels are appropriately controlled.
Other than controlling obvious moisture problems, maintaining heating, air conditioning, and ventilation systems in proper working order is the best way to minimize the potential for mold growth indoors.
The U.S. Environmental Protection Agency has several publications that provide excellent guidance on mold cleanup in homes, offices, and institutional facilities.
Finding a Licensed Mold Contractor
Information on finding a professional to perform mold cleanup can be found at Finding an Indoor Air Quality Professional.
The Maryland Mold Remediation Services Act
In 2008, the Maryland General Assembly passed the Maryland Mold Remediation Services Act. This law requires that any company or firm that provides mold remediation services on residential property in Maryland obtain a license to provide mold remediation services. In addition the law requires that each employee who provides mold remediation services be certified by an accreditation body as a microbial remediation technician or supervisor, whichever is applicable.
This license is to be issued by the Maryland Home Improvement Commission (MHIC), an agency within the Department of Labor, Licensing and Regulation (DLLR). The license to provide mold remediation services is different from the MHIC license for a contractor, subcontractor, or salesperson.
This law was scheduled to take effect on July 1, 2013. However, due to budget constraints, the DLLR has postponed the implementation of the law indefinitely. Therefore, until the Mold Remediation Services Act is implemented, a mold remediation contractor who only performs "cleaning" type services (such as cleaning ventilation systems or applying chemicals to kill mold), would not be required to hold a MHIC license.
Any mold remediation contractor who performs structural renovations to a house in the course of a mold remediation project (for example, tearing out and rebuilding walls, repairing drywall, replacing floors, etc.) is required to hold a MHIC contractor license.
Once the law is implemented, any contractor that currently holds a MHIC contractor or subcontractor license and who also provides mold remediation services on residential properties will be required to hold both the contractor and subcontractor license and the license to provide mold remediation services.
Currently, there are no federal, state, or county regulations for airborne mold contaminants, and standards for an acceptable or tolerable quantity of mold or mold spores have not been established.
As a result, organizations like the Centers for Disease Control and Prevention do not recommend routine sampling for molds.
Generally, it is not necessary to identify the species of mold growing in a building because this is not a reliable indicator of an individual’s health risk. There is so much variability in the way people are affected by mold, as well as the types of mold, that it would be unnecessarily expensive and take a lot of time. If mold is seen or smelled, there is a potential health risk, and steps should be taken to remove the mold. Furthermore, reliable sampling for mold can be expensive.
Surface sampling may be useful to determine if an area has been adequately cleaned or remediated. Sampling for mold should be conducted by professionals who have specific experience in designing mold sampling protocols, sampling methods, and interpreting results.
Chapter 26 of the Montgomery County Code requires that property owners maintain a rental space free from water damage and mold. If you have concerns about mold in your rental property, contact your landlord for assistance.
If your landlord fails to address the problem, you may register a complaint with the Department of Housing and Community Affairs by contacting the County’s Customer Service Center at 240-777-0311 or by filing a complaint on-line at www.montgomerycountymd.gov/311. Enter the keywords “housing complaint” in the search box and click on the “Housing Complaints” link.