HEPA filters are normally as good as MERV 11 filters. But I don't know about the thin ones in vacuum cleaners. The very high air flow might reduce their efficiency for that. Also, the weak link of any filtration system is leakage around the filter. I once had MERV 11 filter installed in my heat pump system and it did no better than the lower MERV filters that I normally used. Dirt merely bypassed both filters around the edges. Maybe you could look at the literature that came with the vac. or some ads if you can find them by googling.

My just replaced geothermal heat pump uses a filter that is 2" thick, but that increases the surface area, not the thickness of the filter material. I suppose there is some air bypassing the filter.

It seems like a "rip off' to sell something like a vacuum cleaner as having a HEPA filter if it doesn't work. I recall Consumer Reports, not a favorite of mine, tests the "emissions" from vacuums it tests. But I can't say I recall that those tests specified how small a particle is trapped.

I think you can make the filter yourself. I had mine sewed by my girlfriend. All you need to do is find a fabric that could filter as tiny as 0.3 micron and sew it. It does make my vacuum sound louder though. I ordered the fabric online mine is at 0.4 micron I think. It cost me $21 a meter. Yes it is kind of expensive but it works just fine i believe. If I can find which store it was I'll post the link here.

I think you can make the filter yourself. I had mine sewed by my girlfriend. All you need to do is find a fabric that could filter as tiny as 0.3 micron and sew it. It does make my vacuum sound louder though. I ordered the fabric online mine is at 0.4 micron I think. It cost me $11 a meter. Yes it is kind of expensive but it works just fine i believe. If I can find which store it was I'll post the link here.

The HEPA filter in my Hoover Wind tunnel is a folded filer (more surface area) and a pre Charcoal filter... it also uses a complex washable sponge plus unknown internals in the filter chain. The Consumer Reports (take with a gain of salt) shows this vacuum as very efficient at trapping dust...

I also now have a room HEPA filter running int eh bedroom.. and new dog beds, and some "Eradicator" spray for the blanket and even the pillow cases... have used on on my pillow cases so far. Also put things outside to shake and let freeze to kill mites. I don't think we have a bed bug problem,no one is suffering from bites.

Unfortunately most vacuums are not sealed systems which allow blow out of dust before it even gets to the HEPA filter and most HEPA filters are pretty lousy excuses for filters. That being said I know personally that Miele S6, S7 and S8 vacuums with HEPA filters are sealed systems and show 0 emissions on Particle Scanners.

Read up on REME Guardian Air filters installed in the HVAC - by far the most notable new option. Local dealers can install.