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Sick buildings: the ventilation conundrum.

According to the Environmental Protection Agency (EPA), up to 30 percent of new and remodeled buildings trigger illness in some of their occupants. Affected individuals exhibit any of a range of nonspecific complaints, including headache, respiratory irritation, asthma-or flu-like symptoms, chest tightness, and fatigue. Over the past decade, many studies have demonstrated that this "sick building" syndrome contributes to increased absenteeism and reduced work efficiency, not to mention physical discomfort.

To combat the problem among office workers, EPA recommends increasing ventilation with outdoor air to at least 20 cubic feet per minute (cfm) per person. But some Canadian office workers perceived absolutely no difference in symptoms or comfort when ventilation rates in their buildings doubled to 60 cfm, according to epidemiologist Richard Menzies and his colleagues at McGill University in Montreal.

Their double-blind, crossover study altered air-exchange rates at four buildings with sealed windows and mechanical ventilation systems every Friday afternoon for three two-week recording periods. On succeeding Wednesday or Thursday afternoons, the Montreal group questioned 1,546 respondents from upper-floor offices, asking about their overall impressions of the work environment and whether it had changed from the previous week. Questionnaires also polled recruits on any symptoms of illness experienced during that day,

Overall, slightly more than half the participants reported at least one symptom each week, Menzies' group reports in the March 25 NEW ENGLAND JOURNAL OF MEDICINE. And while responses differed among buildings, they did not vary within a building during a study period--even though ventilation rates changed up or down (between 30 cfm and 64 cfm) weekly The recruits' unchanging perception of air quality also appears to confound the role of irritants such as formaldehyde and other volatile organic compounds. Concentrations of both doubled or nearly tripled in the air of some buildings when ventilation rates fell to 30 cfm.

The new report does bring "fresh air to the largely untested hypothesis that the sick building syndrome is related to inadequate ventilation with outdoor air," writes Kathleen Kreiss in an accompanying editorial. Kreiss works at the National Jewish Center for Immunology and Respiratory Medicine in Denver.

"The design of this study is very strong and might serve as a model for future research to establish a scientific basis for ventilation standards," comments Mark J. Mendell of the National Institute for Occupational Safety and Health in Cincinnati. However, he cautions, readers "may easily misinterpret this report as having shown that ventilation rate is not related to worker symptoms." And that, he told SCIENCE NEWS, would constitute an "over-interpretation" of the findings.

Menzies' team attempted to compare ventilation rates of 20 and 50 cfm. Owing to the structures' leakiness, however, actual ventilation ended up much higher. The study would have yielded more useful information if it had addressed the most important question about current ventilation. Mendell believes: "the relationship between health effects and ventilation rates between 0 and 20 cfm-- or even 30 cfm per person."

While the findings do suggest that ventilating far above the current standard will not eliminate sick building syndrome, Mendell says, they are of little immediate importance since there is "[no] serious debate about setting ventilation standards anywhere within the range of 30 and 64 cfm per person."

However, Kreiss says, the study does indicate that "we do not know the cause of the sick building syndrome." Moreover, she adds, "science to support prevention, correction, and the setting of standards is woefully underdeveloped and unsupported."
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Title Annotation:ventilation rate and perception of air quality not necessarily related
Author:Raloff, Janet
Publication:Science News
Date:Mar 27, 1993
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