Mold Prevention & Clean Up

Is the mold in my building or in my home toxic?

What are molds?
Molds are simple microscopic organisms.  Almost any natural material will support a population of molds.  They are found on plants, foods, dry leaves, and other organic matter.  Molds have an important role in breaking down organic material.  Molds are essential to what biologists call nutrient cycling.  Nutrient cycling is the process where nutrients get used again and again by living organisms.

Can molds cause me to be ill?
Molds commonly release spores into the air that can cause allergic reactions.  For some people, a relatively small number of spores can cause illness.  However, for other people a larger number of spores must be present to cause illness.  The common symptoms can include wheezing, burning eyes, dry cough, nose and eye irritation, sore throat, or skin rashes.

Are some molds toxic?
Many molds produce toxins that the mold uses to prevent the growth of other organisms.  These toxins may suppress the immune system, cause skin rashes, eye and noise irritation, fever, and in infants rare cases of bleeding in the lungs.  Please consult your physician if you believe your health has been impacted by molds.  Physicians who have an occupational health, public health, or an allergist specialty may have knowledge about this syndrome.

What is the toxic mold described on TV?
The mold described on TV is a mold named Stachybotrys Chartarum (atra) or symple S. atra.  It is suspected that S. atra causes a disorder in infants that results in bleeding in the lungs, however, this condition is rare.  This mold may cause skin rashes, eye and nose irritation, and suppression of the immune system.

How do I know if the S. atra mold is in my house?
S. atra is black, shiny, and slimy.  This mold is most commonly found on straw, hay, and livestock feed.  This mold only grows on high cellulose, low nitrogen materials like wood, paper, cardboard, and building materials like sheetrock that have gotten wet.  In buildings, this mold lives in environments of high humidity and ongoing water damage.  This mold may be present in homes that flooded or had plumbing, roof, or sewer leaks.  S. atra is not common in homes.  It is not the common molds found on shower tiles or along window seals.  However, any molds found in large populations in buildings and homes my cause health problems to some people.

What are the common molds found in homes?
The common molds found in buildings are the mold groups Aspergillus, Penicillium, and Cladosporium.

How can mold become a problem in my building?
Mold is found in virtually all buildings.  Many molds come from outside sources.  Molds can be tolerant of dry conditions but they all need a source of moisture to grow.  Homes and other buildings with mold growth have a moisture problem.  The following are some indoor moisture sources that can cause problems:

  • Flooding
  • Backed-up sewers
  • Leaky roofs
  • Humidifiers
  • Mud or ice dams
  • Plumbing leaks (ongoing)
  • Steam from cooking
  • Steam from baths and showers
  • Improperly vented clothes dryers
  • Improper vented stoves and other combustion appliances
  • Damp basements and crawl spaces
  • House plants

What are the common areas for the S. atra mold to grow in buildings?
In buildings, S. atra lives in water soaked wood, wall paneling, sheetrock, newspaper, and cardboard boxes.  This mold only lives in buildings with high humidity and continual water damage.

Should I have my mold tested?
Accurate mold sampling can be expensive and requires special equipment.  Generally, the State Health Services does no recommend initial testing of molds.  If the testing of molds is necessary, please refer to the sections of your yellow pages entitled "Environmental Consultants" and "Industrial Hygiene Consultants".  Ask if the company is knowledgeable in mold testing.  The County of Lake recommends getting bids.  The consultant show collect the samples according to the procedures detailed in the American Industrial Hygiene Association publication "Field Guide for the Determination of Biological Contaminants in Environmental Samples".

How do I clean up molds?

  • Wear protective clothing, gloves, respirator, and eye protection (goggles or face shield).
  • Fix the source of the water/moisture problem.
  • Begin cleanup by removing all moldy materials including sheetrock, wood products, carpeting, ceiling tiles, and any other porous material.  Bag and throw away all the moldy materials.
  • Allow the area to dry for three days.
  • Clean the area using a stiff brush or cleaning pad along with a non-amonia detergent.  Rinse or vacuum the area.
  • Disinfect the entire area using diluted household chlorine bleach (1.5 cups of chlorine bleach per gallon of water).

Never mix bleach with ammonia - the vapors are toxic!  Caution: Bleach vapors can irritate the eyes, nose, and throat.  Always make sure the working area is well ventilated.  Wear gloves when using disinfectants like bleach.

Please be advised that for large areas of mold (greater than ten square feet), you may want to hire a mold remediation specialist.

Can I become ill from cleaning up mold?
Yes, cleaning up mold may release mold spores.  The mold spore counts in buildings during cleaning may be up to 1000 times that of background levels.  To protect yourself, consider using a respirator to protect you from breathing the mold spores.  Use disposable clothing or clothing that is easily cleanable following the project.  Wear rubber gloves.  Initially, only clean a small area and if you begin to have symptoms stop and hire a mold remediation specialist.  Move air through the building during and after completing the work.  Do not use gasoline pressure washer indoors because you may expose yourself to carbon monoxide.

How do I choose a mold remediation specialist?
Please look in your local telephone directory for the following categories of firms:

  • Water damage emergency services
  • Fire and water damage restoration
  • Pipe and leak locating services
  • Carpet, rub, upholstery cleaners
  • Industrial hygiene firm
  • Contractor referral services
  • Environmental consulting firms

You should contact at least three firms before choosing one to do the work.  Before selecting a firm, obtain information on the firm and the services that they perform.  Ask for references, including clients that have use the firm for similar services.  Describe your problem and ask them if they can diagnose this type of problem.  You should ask the firm how long they have done this type of work and the type of training their employees receive.  Ask the firm how they prevent the spread of contamination and if they sell air cleaners of air duct cleaning services as part of their business.  Check the Better Business Bureau, the California Consumer Fraud Department, and the California Contractor Licensing Board for complaints against the firm.  Beware of any firm who says they are U.S. EPA, U.S. Dept of Labor-OSHA, or State licensed to remove and treat mold in buildings and homes.  These Agencies do not license this service.

How do I prevent mold?
Remember, all molds need the following conditions to grow:

  • Food sources such as organic matter like wood, leaves, paper, and soil
  • Moisture such as humidity or water
  • Space
  • To prevent mold, install and use fans that are vented outdoors in kitchens and bathrooms, ventilate the attic and crawl spaces of your home to prevent moisture accumulation, clean and dry wet carpeting within 24 hours, remove and replace carpeting that cannot be dried, check for cracking of sheetrock, check weather stripping, obtain a dehumidifier, repair leaks promptly, and replace we building materials.

Can the heating and air conditioning ductwork become contaminated?
Yes, the ductwork can become contaminated with mold.  If the duct system is constructed of bare metal or metal with an exterior coating of fiberglass it can be cleaned and replaced.  However, fiberglass ductwork or metal ductwork with an interior coating of fiberglass cannot be cleaned and must be removed and discarded.  You should hire a contractor to do this project.

Where can I get more information?

CA Environmental Health Investigations Branch    (510) 620-3620

U.S. EPA   

U.S. Centers for Disease Control