The MicroGard^® bacterial filter that is used with all Vernier spirometers is effective at filtering both bacteria and many viruses. In independent tests, this filter has shown to have a bacterial filtering efficiency (BFE) and viral filtration efficiency (VFE) that is greater than 99.99% and 99.95% respectively. The viral filtration efficiency tests were performed using bacteriophage virus, which is one of the smallest known viruses at 0.027 microns. For comparison, HIV viruses are 0.042 microns and Hepatitis C viruses are 0.03 micron in size. The COVID-19 virus (SARS-CoV-2) is reported to be 0.12 microns. Bacteria are much larger than viruses. 

For comparison. N95 masks filter particles down to 0.1 microns with 95% efficiency. 

To order bacterial filters see https://www.vernier.com/product/disposable-bacterial-filters-for-spirometer-10-pack/

For information on how to clean the flow head of the Spirometer (SPR-BTA), see https://www.vernier.com/til/4463

For information on sterilizing and disinfecting sensors see https://www.vernier.com/til/6551

More information about the MicroGard^® bacterial filter can be found at the link below: