Lemon-scented products spawn pollutants

While prepping for holiday guests, many hosts will deploy cleaners and air fresheners that impart a pleasant lemon or pine scent. Though they can mask stale smells, their fragrant ingredients—under certain conditions—may also be a rich source of indoor pollution, a study finds.

Several years ago, Charles J. Weschler, a chemist at Telcordia Technologies in Red Bank, N.J., stumbled onto the polluting alter ego of an aromatic citrus compound.