Pulmoguard Filters all but eliminate the possibility of cross contamination. Designed and manufactured by SDI Diagnostics, users are assured that 99.99% of all air contaminates will be removed. During a Pulmonary Function Test, bacteria and viruses are forcefully expelled from the respiratory tract. This represents a real health risk to patients and health care workers alike. The instrument can be contaminated and cause cross contamination of patients. By using a pulmonary filter the risk of cross contamination can be greatly reduced.