2. Why is particle size so important?
In a clinical environment there are many contaminants that can challenge a breathing system, from dust to bacteria and viruses. While dust particles (about 5-7µ in size) can easily be filtered by all modern breathing filters, the smaller bacteria and viruses are more critical. When a filter is capable of filtering the smaller particles with a higher efficiency, it will obviously be more effective than a filter that was tested with a larger particle and achieves a lesser filtration efficiency.
Bacteria can range from 0.25µ to larger than 1.5µ in size. Viruses are even smaller. Hepatitis, for example, is only 0.02µ in size. Following is an illustration of various bacteria and viruses and their size relation to each other. Intersurgical's Filta-Therm® and Filta-Guard™ filters achieved a 99.999% filtration efficiency with particles as small as 0.017µ
In a clinical environment there are many contaminants that can challenge a breathing system, from dust to bacteria and viruses. While dust particles (about 5-7µ in size) can easily be filtered by all modern breathing filters, the smaller bacteria and viruses are more critical. When a filter is capable of filtering the smaller particles with a higher efficiency, it will obviously be more effective than a filter that was tested with a larger particle and achieves a lesser filtration efficiency.
Bacteria can range from 0.25µ to larger than 1.5µ in size. Viruses are even smaller. Hepatitis, for example, is only 0.02µ in size. Following is an illustration of various bacteria and viruses and their size relation to each other. Intersurgical's Filta-Therm® and Filta-Guard™ filters achieved a 99.999% filtration efficiency with particles as small as 0.017µ
Staphylococcus aureus (1.0µ), causes pneumonia, leukemia, sepsis, renal failure, diabetes Pseudomonas diminuta (0.62µ), may cause septicemia Pseudomonas aeruginosa (0.5µ), causes meningitis, septicemia, endocarditis, osteomyelitis, pneumonia Serratia marcescens (0.45µ), causes extraintestinal infections, many nosocomial outbreaks Mycobacterium tuberculosis (0.3µ x 1.0µ is smallest size), causes tuberculosis VIRUSES (see illustration below) Orthomyxovirus (0.12µ), causes influenza Cytomegalovirus (0.1µ), causes e.g. pneumonia HIV (0.08µ), causes Aquired Immunodeficiency Syndrome Adenovirus (0.07µ), causes respiratory infections Hepatitis Virus (0.02µ), causes Hepatitis Bacteriophage MS-2 (0.02µ), test virus for filtration efficiency testing T1-Coliphage (0.017µ), test virus for filtration efficiency testing |
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| Information on particle size taken from "Manual of Clinical Microbiology, 5th edition, Washington DC, 1991" Test protocols available from Customer Service upon request |