More on Mold
The key to prevention in the design and operation of buildings is to limit water and nutrients. The two basic methods for accomplishing that are keeping moisture-sensitive materials dry and, when wetting is likely or unavoidable, using materials that offer a poor substrate for growth. Specifically, design and maintenance strategies must be implemented to manage:
- Rainwater and groundwater, preventing liquid-water entry and accidental humidification of buildings.
- The distribution, use, and disposal of drinking, process, and wash water, making equipment and associated utilities easily accessible for maintenance and repair.
- Water vapor and surface temperatures to avoid accidental condensation.
- The wetting and drying of materials in the building and of soil in crawlspaces during construction.
Little scientific information on the efficacy and impact of prevention strategies is available. Moreover, little of the practical knowledge acquired and applied by design, construction, and maintenance professionals has been subject to thorough validation. Since the 1993 New York City Department of Health (NYCDOH) document (Assessment and remediation of Stachybotrys Atra in Indoor Environments) was produced, a number of other guidance documents have been written, including:
- Fungal Contamination in Buildings: A Guide to Recognition and Management (Health Canada, 1995).
- Control of Moisture Problems Affecting Biological Indoor Air Quality (Flannigan and Morey, 1996).
- Bioaerosols: Assessment and Control (American Conference of Government Industrial Hygienists [ACGIH], 1999).
- Guidelines on Assessment and Remediation of Fungi in Indoor Environments (NYCDOH, 2000).
- Mold Remediation in Schools and Commercial Buildings (U.S. EPA, 2001).
- Report of the Microbial Growth Task Force (The American Industrial Hygiene Association, 2001).
The seven documents were each developed by a group of people with identified expertise in building and engineering issues, mycology, and occupant health assessment. Topics are not uniformly covered by the documents. The documents agree that:
- Mold should not be allowed to colonize materials and furnishings in buildings.
- The underlying moisture condition supporting mold growth should be identified and eliminated.
- The International Society of Indoor Air Quality and Climate (ISIAQ) and ACGIH guidelines discuss moisture dynamics, identifying problematic moisture or remediating moisture problems.
- U.S. EPA guidelines contain specific recommendations for a variety of water-damaged materials.
- The best way to remediate problematic mold growth is to remove it from materials that can be effectively cleaned and to discard materials that cannot be cleaned or are physically damaged beyond use.
- Occupants and workers must be protected from dampness-related contaminants during remediation.
- All the guidelines agree that some mold situations present a small enough exposure potential that cleanup does not require specific containment or worker protection but that other situations warrant full containment, air-pressure management, and full worker protection. Situations between those extremes need intermediate levels of care. Guidance for selecting appropriate containment and worker protection for different situations lacks clarity within and between documents.
- Heating, Ventilation, and Air Condition (HVAC) systems are special cases. The documents disagree on how to respond to contamination in HVAC systems.
- The documents are divided on the use of disinfectants.