Mold

1. What is Mold?
The air we breathe contains many of nature's microbiological living and non-living organisms - bacteria, fungi, virus, and algae. Fungi, for example, include the wide range of microbiological organisms that includes mushrooms, yeast, mildew, and bread molds. Most common fungi require moisture, a temperature range between 40° F and 100° F and a nutrient source to grow, which is the reason mildew forms on many exterior surfaces. While yeast is a single cell fungal organism, mold is the common name applied to filamentous fungi, meaning it is a fungus with many cells.

The amount of fungi in the air is constantly changing, due to the varying nature of the sources that emit fungal spores. Airborne mold spores are typically in the range of 1 to 20 microns (1 micron = 1/1,000,000 meter; 25 microns are approximately 0.001 inch). In the spring and fall, Mother Nature is busy producing the highest airborne concentrations of fungal spores. However, all of us have different health reactions to specific species and concentrations of fungal spores. Thus there is no "standard" baseline the medical community has established for a specific concentration of fungal spores. However, it is generally recognized that the indoor concentration - for commercial and institutional buildings operating with pre-filters and main filters - should be only 10-15 percent of the peak outdoor level.

Why is it important now to know about mold? California enacted a Toxic Mold Prevention Act in 2001, which will require a written disclosure to potential buyers, prospective tenants, renters, landlords, or occupants from anyone who sells, transfers or rents residential, commercial, or industrial real estate, where mold is present which would affect the dwelling unit or building. The legislature in Indiana passed a similar law this year, and it is likely lawyers will extend the requirements for mold disclosure from residential properties to commercial and industrial buildings.

2. Mold in HVAC Systems

Because moisture is needed for mold to grow, many of the components of a heating, ventilation and air-conditioning (HVAC) system having moist air or water present are potential mold growth sites. Not only are cooling coils, condensate pans, humidifiers, air washers, evaporative coolers, and cooling towers major HVAC wet-side equipment on which mold can be found, but also wet internal duct liner and moist ductboard. Carry-over from supply fans can also lodge on the frame of reheat coils, registers, and diffusers, causing mold to also grow on HVAC air-side equipment. The insulation inside built-up Air Handling Units (AHU) upstream of the supply fan can also be a mold site, with moisture from the outside air entering from the air intake and dirt providing the nutrients.

There are different species of mold that grow on all of these HVAC components, so it is not possible to accurately define only one as the "culprit." It is important to recognize there are four types of antimicrobial chemicals that are recognized and approved by EPA:

• Sterilants, are intended to eliminate all microbial organisms
• Disinfectants, designed to eliminate infectious pathogenic bacteria
• Sanitizers, which reduce but do not necessarily eliminate microbial contaminants
• Fungicides, created to inhibit the growth or destroy molds that are pathogenic to humans

Use of any of these chemicals should only be done after thoroughly reading and following the instructions from the manufacturers, as they must be products registered by EPA.

3. How Dangerous is Mold?

Because most TABB technicians are not continually in very close airborne contact with open sources of growing mold, it is unlikely they will be directly exposed to high concentrations of mold spores that would create a health hazard. The important facts are that fungi exist in HVAC systems and can be removed by removing the source of nutrients, reducing the moisture level, and following responsible system cleaning methods. Observing high concentrations of mold growth on HVAC components is clearly a sign of inadequate maintenance and ineffective facility management by the building owner/operator.

The type of activities inside the building should also be recognized as reason to be alert to mold in the HVAC systems. Working in or near the HVAC systems serving an infectious disease area of a healthcare facility requires the use of personal protective procedures. Testing and balancing the HVAC systems in buildings such as prisons, animal shelters, veterinary facilities, and food production facilities may also require personal protective devices and extra caution.

4. Is Mold the TABB Technician's Responsibility?

What do you do when you discover mold during a HVAC system test and balance? The TABB technician is (typically) conducting an air and water balance service, not an IAQ inspection. The inspection of the mold is best left to an industrial hygienist or mycologist, who could render a definitive answer about the mold, the reason(s) it is present, the way(s) to remove its source of growth, and the potential health impact of the mold to the occupants. The TABB technician could state in his/her report, that "a substance which could be mold was evident in the drain pan" or similar such wording, to alert the building owner to the potential problem.

We welcome your comments on this and other issues and will consider them when publishing future issues. Please e-mail to JWilliams@NEMIonline.org.