A safer swim

A team of engineers from

and the

has removed bioaerosols, airborne biological particulate matter, from the air of a hospital therapy pool using a new generation of hybrid filters.

The bioaerosols identified in the unnamed Midwestern hospital pool had sickened nine lifeguards who had become ill with hypersensitivity pneumonitis, a lung condition that mimics pneumonia symptoms.

Lars T. Angenent, Ph.D., Washington University assistant professor of chemical engineering, and the Colorado engineers mounted three high-efficiency particulate air (HEPA) ultraviolet (UV) air filters on the ceiling of the pool room. They compared concentrations of total bacteria, culturable bacteria and airborne endotoxin, a poison present in gram-negative bacterial cell walls that can cause severe inflammatory responses, with and without the air filters operating under similar conditions. They compared the performance of the filters twice, one year apart, and found that the filters reduced concentrations of culturable bacteria by 69 and 80 percent during monitoring periods executed in respective years. The filters reduced concentrations of total bacteria by 12 and 76 percent, respectively, over the same span. But the filters did not affect airborne endotoxin concentrations.