SureGard® is as effective either way (inspiratory or expiratory) the filter media HyperGard® "TEC200gm" (which is published to be the most effective at the flows generated during Spirometry Testing) is tested down to a micron size of 20nm which is less than Hepatitis C.

No filter is 100% effective, as no air would pass through but SureGard® is even published by the “opposition” to be 99.99992% effective against the smallest of Bacteria and Viruses.

Viruses Particle Sizes

 Bacterial Partical Sizes

What all the claims say and what they mean!

Factors that have to be considered in comparing efficacy of Filter Media;

• Size of the organism used in the challenge: Bacteriophage MS-2 is the recognised standard testing organism for many filters. Being one of the smallest used viruses at 20nm it is able to give a higher challenge to the filter media. "TEC200gm" media is tested at this level. Is the media you are using testing up to standard. Nelson Laboratories (USA) test with an Organism of 27nm, CAMR (UK) test with 20nm Organisms.

• Concentration of organisms in challenge: Number of Organisms launched at the media for testing. If you send two Organisms at it the chances of some getting through is slim, send a million (much more can be contained in a sneeze) and you have a higher chance of realistic results.

• Flow rates during testing: If testing is done at 30L/min the filter will record a higher efficiency as the force of the particles is being sent through at a reduced rate, giving the filter longer to work. This is what most filter media's efficiency is published at. NORMAL spirometry testing is actually conducted at flows of up to 750L/min and sometimes above (25x higher). Make sure the figures being published for a filter are relative to their use in the actual environment that they are being used. Nelson Laboratories test at flow rates of 30L/min. CAMR test at realistic flow rates, for Spirometry/Lung Function filters, of 750L/min. 30L/min is only relevant for "normal" breathing not FVC, MVV or even some SVC.

• Multiple Testing Efficiency: Most laboratory filter tests are carried out with a single challenge passed through the media and then the result is recorded. This gives a protection factor that is only representative of one expiratory maneuver. NO inspiratory factor or multiple testing. Again these figures are normally at the less effective rate of 30L/sec or 55L/min. Testing that show a “cross contamination” results are also misleading, as it tests the result after passing through the media two or more times. READ THE FINE PRINT! The “TEC200gm” media is better suited to perform more than one expiratory manoeuvre under real conditions than media's like the 3M Filtrete® media, which is only 100gm or 50gm. The potential problem that may arise with lighter “gm” materials is that, it is suggested, they may break down over several manoeuvres at a realistic higher flow rate than heavier media like the "TEC200gm". In other words, lighter "gm" media may degrade after just one forced expiratory manoeuvre. An example of weight versus filtration efficiency is shown in the below table.
• Resistance: Most of the filter media's on the market, including the "TEC200gm" media in the SureGard® Filter, are within ATS standards. It is a matter of balancing weight to resistance and we believe the SureGard® has the right mix. Many competitors claim they have the lowest resistance or DeltaP, but lower resistance equals reduced filtration. SureGard® is the perfect balancer, even when the "TEC200gm" media is placed into other filter housings the resistance increases. When deciding on a Filter for your purposes, is resistance relevant and if so if it is within ATS is it satisfactory to sacrifice filtration. That's the whole reason for using a filter.

Summary of reports of Efficiency in available filtration media.

What the Experts say:

Even industry experts say to be careful of what about claims that are made, one microbiologist is published in 3M's own literature as saying "There can be many different bacterial removal efficiency ratings for a filter, depending on how the tests where done.". 3M also states "....the numbers can be very misleading, and you cannot be sure that the efficiency rating the manufacturers reports is accurate." 

Even as far back as 1992 people where questioning the filters available on the market and their claims;

"For each brand the ability to filter bacteria may vary from unit to unit. In the devices Group 2 the bacterial filtration is achieved using electrically charged polymer filter media (Filtrete® type G, 3M FILTRETE BV Breda, The Netherlands). According to the manufacturer, the specific density of this medium can vary up to 7%, giving variations in filtering performance of the order of 20% in transmission properties." Heat and moisture exchangers with bacterial filters: a laboratory evaluation, C.Mebius, Dept of Anaesthesiology and Intensive Care Unit, Sabbatsbergs Sjukhus, Stockholm, Sweeden. Acta Anaesthesial Scand 1992: 36: 372-576.

But then;

"Although the bacterial reduction efficiency of filters has been questioned, a new filter material has recently been developed...". "A filter using this material is now available". A cost analysis of two approaches to infection control in a lung function laboratory. Side et al, Aust NZ J Med 1999: 29.

This statement was written with reference to the "TEC200gm" media that is used in the SureGard® Filter Range.

Based on ALL the evidence and published data, SureGard® is the ONLY filter in the World that offers over 99.7% confidence when looking for total infection control protection for patients, staff and equipment against cross infection from all common respiratory bacterial and viral pathogens, like SARS, combined with a patented elliptic mouthpiece.