TRUE HEPA air purifiers, trap the dust and particles with a minimum efficiency of 99.97%, up to 0.3 microns – as measured with my particle counter seen in my YouTube Air Purifier Videos – As seen on ABC 7Over the years, HEPA filtration has become a marketing scheme deployed by both vacuum cleaner and air purifier manufacturers to lure customers to buy products that do not meet the HEPA definition. Most vacuums and air cleaners that I have tested on the market claim to be “HEPA,” however, lack the filtration efficiency and other important benefits that are intrinsic to HEPA technology – so they are “fake HEPA.” They are simply imposters that do not deliver what they claim – in other words, they do not trap the dust.To precisely find real HEPA machines, I test products (where the air flows through) with the particle counter. It is important to note, that I not only test the middle of the filter, but also the side edges and other areas of the chasis, where more often than not, there is high readings due to leakage.Also check-out my blog called Consumer Reporter - a vehicle to educate consumers about the vacuum and air purification market.If you appreciate the information I provide on Miele vacuum cleaners via You Tube and my blog, please support my on-line store, KillDirt.You’ll get free shipping and no tax (as long as you do not live in New Jersey). We will be sure to make your shopping experience a pleasant one.