My vacuum cleaner does not have a HEPA filter and I would like to get
a cleaner that does.

Can someone who understands the physics of HEPA filtration help me
understand HEPA a bit better please. Google is not much of a friend
for this info!

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Is HEPA a registered trademark?

What technology does a HEPA filter make use of? Is it nothing much
more impressive than a very fine aperture standard filter?

is the HEPA filter on a vacuum cleaner likely to need replacing more
often than non-HEPA on account of the greater dust it traps?

Can a HEPA filter be washed or otherwise cleaned so that it can be
reused? Or is the life of a HEPA filter so long that this is not a
consideration.

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Thank you for any info.