ICEID COVERAGE Research continues on shielding workers from airborne pathogens

Jul 14, 2010 ATLANTA (CIDRAP News) – The early response to the H1N1 pandemic exposed ongoing sore points regarding protection of workers in healthcare and other settings during epidemics or bioterrorist attacks, and federal researchers today highlighted current efforts to address some of the concerns.

They covered emerging issues such as a need for more surge capacity for airborne-pathogen isolation units and possible enhancements for guidance on responding to anthrax attacks in workplace settings. The experts presented their updates in a panel discussion at the International Conference on Emerging Infectious Diseases (ICEID).

Kenneth Mead, PhD, a senior research engineer at the National Institute for Occupational Safety and Health (NIOSH) in Cincinnati, said the nation needs a way to quickly boost surge capacity for airborne isolation units such as negative-pressure rooms. In preparing his doctoral dissertation on the topic, he said he found that 40% of hospitals lack engineered airborne isolation rooms, which typically cost between $30,000 and $40,000 to construct.

For example, the state of Nevada has said it has 307 airborne isolation unit beds for its population of 2.5 million, along with 4 million tourists who visit the state each month, he reported.

Adequate protection of healthcare workers is a crucial issue in planning response to major public health events, Mead said. He referred to a study of healthcare workers in New York during the SARS (severe acute respiratory syndrome) episode that revealed that only 24% would report to work.

Current airborne isolation units in hospitals are designed more to protect the hospital environment than the workers or the people being treated in the rooms, Mead said. The systems are based on dilution ventilation, which, because it is so slow to reduce harmful aerosols, doesn't provide a meaningful level of protection.

Mead's dissertation led him to explore ways to cheaply and quickly surge airborne isolation areas in emergency settings. He said current options such as creating a big "hot zone" isolation area or simply transferring patients aren't always practical or worker-friendly.

He explored two other possibilities: creating a "zone within a zone" that replaces the fabric curtain around a patient's hospital bed with plastic and installing a portable HEPA filter within the area, and a ventilated headboard that captures pathogens before they have the chance to disperse.

Field studies at four hospitals showed both options were effective at reducing airborne pathogens, Mead said, and now NIOSH is developing prototypes that are inexpensive and portable for further testing.

Meanwhile, Kenneth Martinez, PhD, a scientist with the Department of Defense, said the US Centers for Disease Control and Prevention (CDC) is supporting research to assess if current anthrax-control protocols in open office environments, such as those that contain cubicles, could be improved.

In a simulated open office setting, scientists have conducted letter-opening simulation trials using spores of Bacillus atrophaeus, an anthrax surrogate, to gauge how quickly workers are exposed and to what extent, Martinez reported. They're exploring whether having the worker who opens the letter wait 5 minutes before leaving the building reduces exposure of other workers. He said so far the waiting period doesn't appear to make a difference.

Scientists are also gauging exposure during emergency response for both the first responders and the letter opener, Martinez said. So far the group has found that spraying the worker with a corn oil substance is effective at preventing spores from re-aerosolizing.

See also:

ICEID home page
http://www.iceid.org/

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