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. While experimenting with the terpene called limonene, Weschler noticed a white message board in the lab turning dingy. Investigation revealed it was building up a thin coat of submicron particles that were forming in reactions between limonene gas and ozone.
Scientists have long known that much of the haze shrouding eastern U.S. forests traces to particulates created in reactions of ozone with terpenes, such as the fragrant pinene emitted by evergreens. The size of these and other small particulates&md