The crawl space is normally an unconditioned area that has a water- resistant vapor barrier that protects the environment (above the barrier) from water intrusion, bacteria and molds. The soil below the vapor barrier will present as most soils do with an abundance of viable microbes. When the vapor barrier is breached the bacteria and fungi will likely be introduced into the crawl space environment. If a stack effect is occurring (Stack Effect is when warm air from an attic moves out of the home through attic vents and the air below (living space and crawlspace) move upwards to fill the vacuum.) If this occurs then odors and microbes from the crawl space may enter the living space of the home and have the potential to impact the health of the occupants.
Many benign and pathogenic organisms live in soils including Actinomycetes which has recently been found to be a bacterium with harmful effects to individuals with a weekend immune system or a biological inability to process this organism. Recent scientific research has demonstrated the importance of identifying the presence of Actinomycetes within an indoor environment. This bacteria may produce symptoms similar to mold exposure and must be removed to allow for the recovery of individuals under medical care.
In many cases, individuals with an environmental illness struggle to identify the source of the contaminants within their homes. Absent leaks, storm damage or a contaminated HVAC system, the location of the contaminants is difficult to identify. In such cases, if the structure has a crawl space it should be investigated to determine if it the vector from the microbes that have invaded the living areas of the home.
Repairing or replacing the vapor barrier may be required as will analyzing the crawl space environment to validate that it is in fact harboring soil bacteria and fungi.
Cleaning may be required as well as other techniques to return the crawl space to a normal ecology. The use of proper ventilation may be considered to move crawl space air to the outside when conditions suggest this approach.