CAMIC Illustration (IMAGE) TechLink Caption Two ports are used in this version of the invention. The first port is connected to a positive-pressure air or oxygen source. A second port is connected to a vacuum line. The vacuum line may feed into an in-line HEPA filter or to the building's exhaust system. Credit US Army illustration via TechLink Usage Restrictions With credit License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.