MISSION // BREATHE EASIER

THE BAD NEWS: ACCORDING TO EPA estimates, indoor air can be five times more polluted than the air outside—and Americans spend an average of 90 percent of their time inside. The good news: Filters made from plants—which host toxin-digesting microbes—can help create purer air. Canadian biologist Alan Darlington, 46, helped come up with the idea in 1994, at Ontario's University of Guelph, while researching air-filtration strategies for the Canadian and European space agencies. Nine years later, he built his first commercial biowall—a polyester-mesh structure embedded with plants like orchids and bromeliads—which reduces some pollutants by as much as 95 percent. Now Darlington's company, Guelph–based Air Quality Solutions, has manufactured eight 32-to-1,500-square-foot walls in Canada and installed the first U.S. wall at Biohabitats, an environmental-restoration firm in Baltimore, this past September. What's next? Biowalls small enough for private homes, which Darlington hopes to unveil in 2007.