Why you should be using bacterial filters for your spirometry testing

Whilst many pulmonary function departments in hospitals are using bacterial/viral filters when performing spirometry tests, in primary care relatively few GP practices have previously used bacterial filters when performing these types of lung function tests.

Improving infection control

The recent COVID-19 pandemic has highlighted a need for improved infection control and the use of bacterial filters, instead of traditional one-way cardboard mouthpieces, is another way of reducing the risk of cross contamination during lung function testing.

All patients are susceptible to the risk of infection after performing pulmonary function tests and there is often very little screening of a patient’s infectious status before any testing is carried out. The use of stringent precautions, such as bacterial filters, can be very beneficial in preventing the spread of infection.

It has also been found that there is little reduction in lung function measurements caused by using bacterial filters over other cardboard mouthpieces. 

The benefits of bacterial filters

Bacterial filters offer a range of benefits to both the patient and the practice over using standard one-way cardboard mouthpieces:

- They prevent up to 99.99% of bacteria and virus cross-contamination during lung function tests - Tests performed by Nelson Laboratories found on our Disposable Bacterial/Viral Filters found that they were over 99.99% efficient in capturing bacterial and viral contaminants and tests performed by the Health Protection Agency in England found the filters to capture over 99.4% of aerosol borne micro-organism spores of two different types tested.

- They protect breathing circuits, especially flow sensors, from contamination with droplets of saliva and mucus that may introduce errors in test measurement.

- Patients and staff are better protected from inhaling pathogens from the breathing circuitry.

Using bacterial filters at your practice

Our Disposable Bacterial/Viral Filters are ergonomically shaped to allow the patient to use the filter itself as a mouthpiece, rather than having to add a traditional cardboard spirometry mouthpiece. This decreases dead space and reduces the cost to the practice to as little as 84p per test.

They are compatible with all the current leading brands of spirometer, including CareFusion (Micro Medical), Vitalograph, Easy On-PC and our own SpiroConnect spirometer. You can purchase bacterial filters on our website here.


Zhang Y. Using barrier filters to protect spirometer sensors from droplet deposition. Letter to editor. Chest 2005; 127: 2294. BACTERIAL/VIRAL FILTERS IN PULMONARY FUNCTION DEPARTMENTS - http://www.wales.nhs.uk/sitesplus/documents/861/bacterial%20viral%20filter%20info.pdf

Effect of bacterial filters on spirometry measurements - http://adc.bmj.com/content/85/4/346.full

HPA. An evaluation of Filtration Efficiencies Against Bacterial and Viral Aerosol Challenges - https://numed.co.uk/documents/download/275?url=http%3A%2F%2Fnumed.co.uk%2Fproducts%2Fdisposable-bacterial-filter-for-spirometry

Nelson Laboratories. Virus Filtration Efficiency Test (VFE) at an Increased Challenge Level - https://numed.co.uk/documents/download/276?url=http%3A%2F%2Fnumed.co.uk%2Fproducts%2Fdisposable-bacterial-filter-for-spirometry