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In the first of three articles, this air quality professional starts by addressing prevention and pitfalls alike. Articles focusing on IAQ occupant responses and liability issues will follow in coming months.
As indoor air quality (IAQ) professionals, we observe many conditions that can contribute to deteriorated IAQ. The manifestation of these problems is occupant compaints regarding odors, Sick Building Syndrome (headaches; buning eyes, nose, and throat; coughing; and sneezing), building-related illnesses (Legionnaire's disease, asbestosis), and chemical sensitivities of an extreme nature (multiple chemical sense tivity, Twentieth Century Disease, chemical allergies, and other similar diagnoses).
Building problems can cause degraded air quality in all phases of a building's life-- cycle: design, operation, and maintenance. The purpose of this article is to examine common design characteristics that may be problematic to the achievement of acceptable IAQ and that are generally easily identi$ed and are usually avoidable.
SIZING SYMPTOMS
Depending on the size and scope of the project, building design can be a very complicated process. Table 1 lists a variety of problems which can occur and their possible negative influence on IAQ.
A not-so-uncommon problem is an oversized air conditioning system. The oversized system could be due to a design error or seasonally reduced occupancy/thermal loads such as often occurs in schools in summer-- time. The oversized system causes rapid response to high temperatures. However, because of oversizing, hot, humid air brought into the system is not adequately dehumidified, producing increased relative humidity (rh) in the space. Sustained rh above 60% increases the likelihood of microbiological growth on environmental surfaces. The airhandling system can serve as a distribution conduit for microbes throughout the zone.
INSULATION
Wetting of hvac interior insulation is problematic with respect to IAQ in several regards. Interior insulation in ductwork comes in a variety of forms. One of the most common forms is unfaced fiberglass insulation, which is glued and/or pinned to ductwork. When such insulation becomes saturated, this duct lining becomes an amplification site for microbial contamination.
In addition, this fiberglass can be easily eroded because of high-velocity air contact with the surface of the insulation. This erosion can result in the dissemination of fiberglass throughout the zone where occupants can either inhale the fiberglass or, quite commonly, appear to experience dermal...