Environmental Engineering Reference
In-Depth Information
provide a minimum of 20 CFM (9.5 L/sec) per person outdoor air to office
building spaces and 15 CFM (7.14 L/sec) per person outdoor air in school
buildings. Achievement of these requirements necessitates that mechanical
systems be adequately maintained to provide desired air flows throughout
the system, that adequate control be maintained over ventilation system air
flows, and that facilities staff are sufficiently trained in the operation of
HVAC systems.
HVAC system operation requires maintaining balanced air flows by (1)
using correct damper settings, (2) ensuring that filters are changed frequently
to maintain desired system flow rates, (3) ensuring that all equipment is
operating properly, and (4) keeping condensate drip pans open and relatively
clean of microbial growth. Outdoor air flows should be sufficient to balance
or more than compensate for building exhaust to minimize re-entry and
entrainment problems.
As indicated in Chapter 7, surface dust is apparently a major risk factor
for SBS-type symptoms. As such, surface dust can only be reduced and
maintained at acceptable levels by scrupulously cleaning horizontal building
surfaces. Such cleaning by service personnel is inadequate in most buildings.
In a survey study of school teachers conducted by the author in Indiana,
three factors were observed to be significantly and independently associated
with SBS-type symptoms reported. These were inadequate ventilation, mold
infestation, and surface dustiness or inadequate cleaning. Each of these
school SBS-type symptom risk factors is directly associated with improper
or inadequate building O&M practices.
A variety of other O&M practices can be implemented in buildings by
facilities management to minimize contamination problems and occupant
complaints. These include (1) scheduling renovation activities (such as paint-
ing) on days when the building is unoccupied (e.g., summer in the case of
schools) or using high ventilation rates when renovation activities are con-
ducted during occupancy; (2) wet shampooing carpeting under well-venti-
lated building conditions; (3) limiting the use of insecticidal applications for
cockroach control to the crack and crevice method or poison baits, or, more
appropriately, employing integrated pest management; (4) waxing floors
after hours under ventilated conditions; and (5) using low-volatility/low-
toxicity boiler additives in steam humidification.
Specific building O&M practices designed to manage potential asbestos
and lead hazards in place, as well as biological contaminants, are described
later in this chapter.
II. Mitigation measures
Source control measures have been described in the context of preventing
or avoiding indoor contamination problems. Though highly desirable,
source avoidance or prevention principles are, in many cases, not employed.
As a consequence, source control measures must often be implemented to
reduce contaminant exposures and resolve health, comfort, and odor com-
