BACTERIAL & VIRAL FILTRATION EFFICIENCY

Filters tested by Nelson Laboratories, an FDA approved independent lab,  and found to be over 99% effective for filtering viruses and bacteria. It is important to know the Viral Filtration Efficiency Study was performed using the bacteriophage virus, which is one of the smallest known viruses at 0.027 microns in size. It represents a severe challenge to the filter media given that the HIV virus is 0.042 microns and Hepatitis C is 0.03 microns.

Of course all bacteria are significantly larger than viruses with TB ranging from 0.5 – 1 micron in diameter and 1- 5 microns in length. The Bacterial Filtration Efficiency tests proved equally effective.

Bacteria and viruses normally need a media in which to travel. In exhaled air, they are entrained within aerosolized droplets in the 0.1 to 22 micron range. A key issue to understand is the filter is not intended to function as a “sieve” where particles are caught because they are too big to pass between the fibers.  The filter media combines several technological features to maximize filtration while allowing gas to flow through with minimal resistance.

1. Inertial Impaction: Larger particles collide with the filter because they cannot follow the airstream as it moves around the fibers.
2. Direct Interception: Intermediate-sized particles are captured as they follow the airstream and come within a half-particle diameter of the fiber.
3. Brownian Diffusion: Particles smaller than 0.1 microns are bounced around by the motion of the air molecules, causing the particles to come into contact with the fibers.
4. Electrostatic Attraction: Fibers have a permanent electrical charge to attract any particles in their vicinity, which greatly increases the filter’s ability to capture particles.

As a practical matter the independent tests demonstrate the Polytechnic Filter is highly effective in capturing viruses and bacteria considerably smaller than those found in exhaled gas.

WARNING: Spirometry tests performed without using a filter exposes equipment to expectorant matter and potential patient cross-contamination.