More About Indoor Air Technology
A number of air-cleaning technologies are designed to either remove gaseous air pollutants or convert them to (ideally) harmless byproducts using a combination of physical and chemical processes.
Gas-phase air-cleaning technologies include adsorbent media air filters such as activated carbon, chemisorbant media air filters, photocatalytic oxidation (PCO), plasma, and intentional ozone generators sold as air cleaners. Compared to the control of PM, gas-phase pollutant control is much more complex.
Only adsorbent and chemisorbant media air filters have been shown to be effective gas-phase air cleaners for some gaseous pollutants without producing potentially harmful byproducts, although not all gaseous air pollutants are removed equally.
Most studies have reported reductions in PM exposures with the use of high-efficiency particulate air (HEPA) or other high-efficiency portable air cleaners on the order of approximately 50 percent or higher. source: epa.gov