Tight buildings, more airborne disease?

Tight buildings, more airborne disease

Residents of new buildings with modern, energy-saving heating and air conditioning systems get respiratory infections significantly more often than residents of older buildings, reports a team of doctors. In a four-year study of army trainees at four different training camps, the researchers found an incidence of respiratory diseases 45 percent greater among trainees housed in modern barracks than among those housed in barracks built in the 1940s and 1950s. They attribute the differences to modern heating and cooling systems, which recirculate about 95 percent of the air in the buildings to save energy. The older, less-energy-efficient buildings reused only 50 to 60 percent of the air in the building and mixed in outdoor air for the remainder.

While the researchers found increased risk of infection in new buildings, they say there are still too many unstudied factors to decide why this is so. The study, reported in the April 8 issue of the JOURNAL OF THE AMERICAN MEDICAL ASSOCIATION, is the first long-term study of building-associated respiratory disease to be made with such a large, uniform group: The trainees were randomly assigned to barracks, were immunized at the same time, and were outdoors and indoors in the same weather for identical time periods.

The authors note that respiratory infections in the United States account for 75 million doctor visits and $15 billion in direct medical costs each year. During flu epidemics, indoor airborne infections may account for thousands of deaths and billions of dollars in social and health costs, they add.