Solid Science Practical Solutions


September is Mold Awareness Month

Q – I’ve heard a lot about “toxic mold” and “black deadly mold” in the media - How concerned should I be?


A - That question is one of the reasons that the United States Environmental Protection Agency has designated September as “Mold Awareness Month”.  Those alarming terms show up in the media on a regular basis.  Some mold-related companies use them as scare tactics to frighten homeowners, tenants and building owners into action.  Such terms are not based on good science and are not useful in understanding the risks of mold exposure and making good decisions.


Your concern should be based on multiple factors such as:

  • The extent, duration and location of mold growth
  • The source of moisture (one time event vs. ongoing problem)
  • Types of building materials impacted
  • Personal health histories and medical status of occupants
  • Occupancy patterns and activities
  • Type and maintenance of heating and cooling systems
  • The outside environment in which the building is located

In general, the longer you are exposed to mold and the higher the levels of exposure, the greater the risk of negative health effects.  The actual risks are difficult to determine and depend on the above factors and each individual’s immune response to the exposure.  That is one of the key reasons that there are no government regulations or exposure limits for mold. 


Increased risk is often associated with:

  • People with known mold or other outdoor allergies
  • People with compromised immune systems
  • People with chronic (especially respiratory system related) diseases
  • The elderly and very young
  • Those occupying chronically “damp” buildings

However, some healthy people can also develop sensitivity to mold and get sick from mold exposure.


Q - What are the major known health effects from mold exposure?


A - The best documented health effects are upper respiratory and “hay fever-like” symptoms such as cough, sneezing, headaches, tightness in the chest, scratchy throat, difficulty breathing, red and itchy eyes, etc.  Science has also shown that mold exposure can cause asthma or make it worse in some people.  Other medical information suggests a link between mold exposure and lower respiratory issues such as bronchitis and emphysema.  Despite media reports, we do not yet have proven medical evidence that environmental mold exposure causes other conditions such cancer, heart or skin diseases; studies are ongoing.


The duration of symptoms varies depending on the individual’s health status.  In some cases, the health effects can be long lasting or life-long.


Q - What exactly is mold?


A - According to the Center for Disease Control molds are living organisms in the Kingdom Fungi.  They mostly come from the outdoors from trees and other vegetation, but mold is found almost everywhere.  Molds grow best in warm, damp, and humid conditions, and spread and reproduce by producing spores which are microscopic, tough and can float in the air for long periods of time.  This fact is especially important in buildings with forced air duct systems which can help spread mold spores throughout the building.  No one knows how many species of mold exist but it is estimated that there are “hundreds of thousands”.  Mold can grow on virtually any organic substance, which means most common household and building materials are susceptible, including wood, paper, wallboard (sheetrock), insulation, clothing, leather good, carpets and foods.


Q - Mold has been around forever – Why is it such an important issue lately?


A - Many older buildings were constructed of masonry and hardwoods with minimal insulation.  Such buildings were less susceptible to mold since the materials were harder for molds to grow on and as air and moisture moved in and out, building materials tended to dry faster.  Newer buildings are more energy efficient, which also serves to trap in moisture (and indoor air contaminants) and reduce fresh air, leading to higher risk for microbial growth.  Medical science has also learned a lot about the health effects of molds in recent years, although there is still much research to be done.


Q - What should I do if I suspect mold?


A - Since mold control largely depends on moisture control, here are several helpful tips:


  1. Don’t panic!  Not all wet building materials become moldy and not all mold conditions are serious. 
  2. Don’t ignore possible signs of mold.  Immediately look for possible sources of moisture without disturbing suspected mold (disturbance can spread microscopic mold spores into the air and around the building).  
  3. Repair sources of water as soon as possible and dry the area quickly.
  4. Temporarily protect/seal the suspected moldy area by taping heavy gauge plastic over the area, being careful to leave a safe margin of at least 1 foot around the discolored area.
  5. Small areas (<10 sq. ft.) of visible mold on wallboard or other materials can usually be removed by a non-professional using basic precautions.
  6. If you find or suspect more than 10 sq. ft. of mold or smell “musty” or “earthy” odors but don’t see any water damage or leaks, consider the services of a professional Industrial Hygienist or Indoor Environmental Consultant.  Such qualified professionals can evaluate the problem, test as needed and provide objective guidance on safely remediating the mold. 

CAUTION:  To avoid a conflict of interest and potential rip-offs, the best source of objective advice is from a consultant who is not also a mold contractor.


Q – What can I do to prevent mold?

A – Proven strategies include:


Periodically inspect for signs of water leaks, with special attention to attics, basements and plumbing fixtures.  Areas around and behind tile showers are at high risk for leaks and related damage.  Respond immediately to leaks to prevent mold and related damage.


Change HVAC filters (quarterly) and look for signs of standing water in and around the furnace.


Maintain indoor relative humidity levels at or below 55%, especially during hot and humid months.  Operate dehumidifiers and/or humidistat vent fans in basements or crawlspaces during the summer.


Do not store basement contents on the floor or directly against foundation walls.  Long term stored items should be in sealed durable plastic tubs rather than cardboard boxes.


Open windows or use vent fans in bathrooms during, and for 30 minutes after, showers or baths to reduce humidity levels and the risk for mold.


Despite the best preventive efforts, water intrusion related damage and mold can happen.  How you respond can make the difference between a small event and a major case involving health problems, expensive repairs or reconstruction, regulatory enforcement and possible litigation.