HEPA filter
You often hear HEPA or HEPA filters mentioned in vacuum cleaner advertisements and may have wondered what they mean by that. As HEPA stands for High-Energy Particle Acceleration, a HEPA filter exists to prevent a vacuum cleaner from essentially functioning as a particle accelerator. As is commonly known, accelerated high-energy particles colliding with other particles pelt the surroundings with radiation and electricity, which is considered dangerous to the health of the non-mutant population..
History[edit]
As the suction of a modern vacuum cleaner grew larger due to improved efficiency and higher power requirements after the 1980s, it effected a larger and faster exhaust air flow that accelerated the vacuumed particular matter to higher velocities and energies. The need for a new kind of filter became obvious when the rate of domestic electric and radiation burns kept climbing.
Technical detail[edit]
A large air-flow ionizes and accelerates particles within it. Those energized particles then collide with stationary particles and each other, to release alpha, beta and gamma radiation and form new charged particles. A HEPA filter scrubs out the charged and high-energy particles and slows down the air flow to prevent new ones from being created. This prevents radiation and large electric currents within the exhaust air flow. To qualify as HEPA by US government standards, the air after the filter has to at maximum radiate at a rate and power comparable to 99.97% of the natural background radiation and all charged or radiating particles that have a size of 0.3 µm or larger have to be filtered out. A filter that is qualified as HEPA is also subject to interior classifications.
Although the incoming air flow and the air within a vacuum cleaner also move at higher velocities, creating particle collisions and differences in electric potential resulting in potentially lethal electric currents, they are not considered problematic as the radiation and the electric charges are insulated and neutralized within the protective shell of the device, thus preventing them from harming the user. It is discouraged, however, to point running vacuum cleaners at living things. One should also use protective suits when removing and disposing of the collected dust or changing the cleaner heads.