Are all HEPA filters the same?

Question

While researching lead cleanup I read that some HEPA filters are rated to ANSI and other specifications-

Are all HEPA filters rated to these same specs or is HEPA just a marketing term that companies are using to give consumers a warm fuzzy?

I don't see any sort of 'class' or 'rating' along with most HEPAs so where could I even go to find out what specs my HEPA filter meets?

Answer 1

No, they are not all the same.

Surprisingly, you particularly want to avoid ones labeled as "hospital grade".

Choose your HEPA filters based on the fraction of particles of a specific size that the filter catches, such as "captures 99.99% of particles > 0.3 micrometers.

I also found this note (http://www.wisegeek.com/what-is-a-hepa-f... while looking around:

The rating for a HEPA filter is based on capturing nearly all microns .3 in size, verses .1 or even .001 because .3 microns are the hardest size to trap and the optimal size for passing into the human respiratory system. Therefore the .3 micron efficiency rating sets the highest standard.

Answer 2

HEPA isn't just a marketing term to promote filter products and they aren't all the same. The term signifies filters designed for high particulate removal efficiency (most commonly specified to be better than 99.97%) at particle sizes around 0.3 micrometer (the most difficult particle size to trap with a mechanical filter). HEPA filters have been progressively developed since the 1940's to meet the needs of the nuclear, pharmaceutical, health care, aerospace, and micro-electronics industries (apart from being used in domestic vacuum cleaners to trap pollen and insect f***s).

HEPA filter ratings are usually based on their dust holding capacity, and air resistances across the filter under clean and dirty conditions.