Some have eco-friendly attributes, like wood with low emissions of volatile organiccompounds (VOCs), such as formaldehyde, which is classified as a carcinogen by the World Health Organization.
Preventing leaks also cuts back on other air pollutants associated with gas production and use, including such volatile organiccompounds as ethane and butane.
UTC's solution: Pass the return air through an aluminum filter sprayed with titanium dioxide that, hit with ultraviolet rays, sets off a chemical reaction that breaks down nasty organiccompounds like benzene and formaldehyde into carbon dioxide and water.