The leafy friend you've nurtured since college offers a little nurturing itself: Certain plants can freshen the air by absorbing household toxins, such as the formaldehyde found in dry-cleaned clothes and the benzene in tobacco smoke. They won't noticeably reduce odors in your home, but they will improve the quality of the air you breathe.

In testing done by NASA on sealed spaces, tropical and subtropical plants were found to work best because their broad, dense leaves and strong roots efficiently take in harmful gases. "The plants store the toxins and don't release them back into the air," says Mobee Weinstein, assistant foreman of gardeners at the New York Botanical Garden. Indoor plants, which give off healthy doses of oxygen, are especially effective in bedrooms, where we spend about a third of our day. The low-maintenance areca palm and the peace lily are widely available and absorb most common pollutants. If you're famous for killing cacti, however, stick to the usual air-filtering suspects.