|In 2002, the California Air Resources Board (ARB)
and the California Department of Health Services conducted a study of the Environmental Health Conditions in California's
Portable Classrooms (PCS). The results indicated that a substantial percentage of California classrooms have indoor
environmental quality (IEQ) problems. The California Energy Commission (Commission) and ARB funded subsequent analyses
of the PCS data to help refine specific recommendations and guide further activities for preventing IEQ problems
in schools. This report discusses those analyses.
The objectives of this study were to characterize the distribution of energy and comfort-related characteristics
of portable and traditional classrooms and to explore in detail the relationships among key building variables
and IEQ measures in the PCS data set. Statistical analyses were conducted to determine the greatest predictors
of IEQ measures. Stepwise linear or logistic regression analysis was used to model IEQ measures such as classroom
temperature, indoor and outdoor pollutant levels, light, and teacher satisfaction. The independent variables in
the models were measures of mechanical ventilation, natural ventilation, lighting, and socioeconomic status, as
well as source-related variables and general variables (e.g., region, classroom type, school location, etc.).
The results showed that all but a few of the mechanical ventilation variables had minimal effect on most of the
outcome IEQ measures, while natural ventilation variables (e.g., number of windows opened) were inversely associated
with aldehyde, humidity, CO2, and tetrachloroethylene. None of the lighting models were statistically significant.
The socioeconomic variables were important predictors only for VOCs, outdoor formaldehyde levels and indoor-outdoor
CO2 difference (a surrogate for air exchange rate). The general variables were strong predictors for all modeled
IEQ measures except allergens and lighting.
In general, the models suggests that the source-related measures and general characteristics of the schools and
classrooms are better predictors of the IEQ measures than the mechanical and natural ventilation building characteristics.
Differences were observed in IEQ between portable and traditional classrooms for temperature, humidity, aldehyde
and VOC levels, one CO2 measure and one measure of teacher satisfaction. Whether portable or traditional classrooms
had better IEQ depended upon the modeled indicator.
|Robert Clickner, Ph.D., is an Associate Director at Westat and a senior statistician
with more than 30 years of experience in the development, implementation, operations, and management of statistical
and environmental research projects. He has directed a number of major environmental studies of exposure to heavy
metals, pesticides, lead-based paint in homes, indoor air pollution, asbestos in buildings, and industrial solid
waste. Also, he has been the principal or co-principal investigator on numerous environmental epidemiological studies,
including studies of microorganisms in recreational water, mercury in seafood, indoor environment health hazards
in workplaces and schools, and lead in children's home environments. Dr. Clickner has designed and analyzed national
statistical surveys using a variety of optimization and modeling techniques, including area probability sampling
and random digit dialing. He has developed sample selection and data collection protocols and has supervised their
execution. He has also designed, conducted, and analyzed biostatistical experiments involving pesticides and other
environmental contaminants. His project management activities have included the development and maintenance of
project completion plans, quality assurance plans, operations logistics, schedules, budgets, and submissions to
institutional review boards and OMB; management and coordination of multiple subcontractors, including numerous
laboratories; staff assignments; review of deliverables; and client coordination and communication. Dr. Clickner
has presented numerous invited papers before universities, professional and technical organizations, and international
institutes. He has developed and conducted international workshops on methodologies for human exposure assessment
field studies. Dr. Clickner has been a member of the Board of Councilors of the International Society of Exposure
Analysis and is currently the chairman of the nominations committee.
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