Pall Breathing System Filters and Protection Against Influenza

May 7, 2009

Dear Customer:

Influenza is in the headline news almost every day.  The potential occurrence of a flu pandemic after mutation of the H1N1 virus causes concerns to the public and to healthcare professionals. In this context Pall has been asked the question: “Do Pall Breathing System Filters protect against the spread of virus from an infected patient into the breathing system, and in turn, via the ventilator into the ambient air of the hospital?”

In order to act as a barrier to the transmission of bacteria and viruses via the breathing system, a filter must effectively block different potential routes of transmission.

Infective organisms may be contained in a patient’s saliva or bronchial secretions. Coughing or airway suctioning can generate a spray of small droplets containing the infective agent. During passage through dry air, the liquid coating of the droplet may dry out and form an even smaller droplet nucleus.  Droplet nuclei may contain the infectious organism, and may remain airborne for prolonged periods of time. Thus, infectious organisms may be transmitted via airborne droplet nuclei or liquid secretions.

Pall Corporation has conducted extensive validation work to show that Pall Breathing System Filters act as a barrier to these routes of transmission.

Validation testing of breathing filters with all known pathogens is not possible, nor is it necessary in order to demonstrate their efficacy. Pall Breathing System Filters have been tested with a variety of clinically relevant bacteria (including:  Mycobacterium tuberculosis1, Pseudomonas aeruginosa2, Bacillus subtilis3, Staphylococcus aureus4) and viruses (including, Human Immunodeficiency Virus5 and Hepatitis C Virus6). In addition, these filters have been subjected to testing with bacterial (Brevundimonas diminuta7) and viral (MS-2 bacteriophage7) organisms that represent gold standards for exclusion on the basis of size. These studies have demonstrated that Pall Breathing System Filters offer an effective barrier to contaminated liquids, and have an airborne bacterial and viral removal efficiency of at least 99.999%.

Given the size of the influenza virus (80-120 nm), its survival rate on inanimate surfaces, and using these studies as a guide, there would be no reason to expect that Pall Breathing System Filters would not be equally effective in preventing the passage of influenza virus.

We trust this information is helpful to you. For further details, please contact your local Pall representative.


Dr. Joseph S. Cervia, M.D., M.B.A., FACP, FAAP, FIDSA
Clinical Professor of Medicine and Pediatrics
Albert Einstein College of Medicine
Medical Director
Senior Vice President, Biomedical Division
Pall Medical

1 Aranha-Creado, H. et al. Infect Control Hosp Epidemiol 1997;18:252 - 254
2 Willie B. Krh.-Hyg. +Inf.verh. 1990;12:24
3 Wilkes A.R. et al. Brit J Anaesthesia 1999; 82:461 - 462
4 Rosales M & Dominguez V. 2nd International Conference on Prevention of Infection, Nice, France, 4-5th May 1992
5 Lloyd G et al. Centre for Applied Microbiology and Research, 1997.
6 Lloyd G et al. Anaesthesia and Intensive Care 1997;25:235-238.
7 Pan L. et al. Pall Corporation Technical Report BCF2, 1995