While there are no laws in California that govern mold exposure, there are many guidelines addressing mold exposure and remediation published by governmental enforcement agencies such as the Occupational Safety and Health Administration(OSHA), the Environmental Protection Agency (EPA), Center for Disease Control (CDC) and the California Department of Public Health (CDPH) to name a few.  Uniformly these agencies agree that there are adverse health affects associated with exposure to mold spores.  There have been no mold exposure regulations established in California primarily because of the inability to establish a Permissible Exposure Limit (PEL) for exposure.  The PEL is difficult to establish as people will react differently to mold exposure based on their physiology and the fact that mold spores are ubiquitous both in indoor and outdoor environments.  Many institutions including the American Industrial Hygiene Association (AIHA) and the American Council of Governmental Industrial Hygienist (ACGIH) have determined that when establishing the potential for mold exposure in indoor environments there should be sampling conducted on the exterior of the subject interior environment and the results of both the interior and exterior samples should have similar biodiversity of mold spores. 

Identifying Moisture Problems

Identifying the source of mold growth can be difficult or obvious.   Many times the concern for mold exposure arises days or months after a water loss has occurred.  This can take place if the initial work was not conducted appropriately or the source of the water intrusion was not corrected.  It can be difficult to establish a source of the mold exposure after the water intrusion source has been corrected and there are no obvious existing areas of water intrusion.  As part of an initial inspection a mold inspector should assess the moisture content of building materials in the suspect areas, assess the relative humidity levels inside the subject area and other areas of the property compared to the exterior relative humidity levels, a thermal imaging camera can also be a useful tool when conducting an assessment as it can show the inspector areas within a wall cavity with disparate temperatures which can be related to water intrusion. 

Aspergillus Mold Spore

Mold Sampling

Typically if visible mold growth is identified as part of an initial inspection there would be no need to conduct sampling as the remediation activities would not vary based on the type of mold present.   If identification of the mold type is preferred there are a few different ways to collect the samples, a tape lift sample can be collected from affected surfaces, a bulk material sample can be collected if there is growth that penetrates a building material and a swab sample can be collected to allow for the culturing of the growth material.  Which sample is collected will depend on the conditions at the subject site.

If mold exposure is of concern air samples can be collected.  The typical screening air sampling consist of the use of an Air-O-Cell or similar cassette.  The Air-O-Cell or equivialant air sample cassette allows for the analysis of viable and non-viable mold spores.  This technique is useful as not all mold spores are viable and would not be identified using a culturable sample media.  The other type of air sampling uses cutlure plates with a set volume of air collected allowing the airborne mold spores to impact in the agar (or other media) and the culture plates are then cultured for several days.  Once the mold spores start growing the culture plate can be analyzed and mold spores can be identified down to the species. 

All mold analysis and interpretation must be conducted in accordance with AIHA, ACGIH or other professional guidelines.

Links to useful websites:

http://www.osha.gov/Publications/preventing_mold.pdf

http://www.cdph.ca.gov/programs/IAQ/Documents/moldInMyWorkPlace.pdf

http://www.epa.gov/iedmold1/pdfs/moldguide.pdf

http://www.cdc.gov/mold/faqs.htm