Most filtration systems currently posses a pore size of approximately 300 nm.   While this is sufficient to block several larger pollutant molecules, viruses and infectious bacteria can pass through without impedance.   A new generation of nanofilters being developed with a pore size of approximately 30 nm can block many infectious diseases, including Hepatitis B, SARS, and HIV, while still permitting air and water molecules to pass through.   As early as 2002, nanofiltration systems were being employed to filter river water in France to produce water that was safe to drink.

Though the most common filtering products utilize some sort of powered or block carbon as a filtering medium, recent developments have produced an activated carbon fabric that is easier to use and install and isn’t as messy as regular carbon filters.   But nanofiltering technology isn’t limited to carbon based filters.   Recently, several non-organic nanofilter products have been released to the consumer market.   Among these are the Genesis Air Filtration Systems by Genesis Air which uses filters and ultraviolet technology, NanoCeram by Argonide which are alumina filters, and the nanofiber Spider-Web and Ultra-Web filters by Donaldson, of varying composition.

Carbon nanotubes are also being applied to filtration systems.   A new method of arranging carbon nanotubes radially in a quartz cylinder permits the filtration of water, removing bacteria and viruses even as small as 25 nanometers wide (such as the polio virus).   While the water can move through the nanometer sized pores of carbon nanotubes, larger molecules and organisms cannot.   These CNT-based filters have the added benefit of being easy to clean through ultrasonic methods.

Nanofilters are also being considered for use in filtering proteins, primarily for medical applications.   University of California, Davis researchers Kyoung-Yong Chun and Pieter Stroeve developed a method of filtering proteins of similar size through a nano-gold particle coated polycarbonate membrane (pore size of approximately 10 nm) by changing the pH value of the solution the membrane was immersed in, using a method called “electrostatic screening.”