Laundry vents emit hazardous air pollutants when people use popular fragranced laundry detergents and dryer sheets, according to research published in Air Quality, Atmosphere & Health.

The research found more than 25 volatile organic compounds, including seven hazardous air pollutants, coming out of the vents when the top-selling products were used. Of those, two chemicals – acetaldehyde and benzene – are classified by the Environmental Protection Agency as carcinogens.

"These products can affect not only personal health, but also public and environmental health," said lead author Anne Steinemann, a University of Washington professor. "The chemicals can go into the air, down the drain and into water bodies."

Almost none of the volatile chemicals emitted from the products were listed on the products label. Instead, the labels referred to the chemicals in general terms, such as "biodegradable surfactants," "softeners," or "perfume."

U.S. law does not require companies to label the chemicals in mixtures of "fragrances."

"This is an interesting source of pollution because emissions from dryer vents are essentially unregulated and unmonitored," Steinemann noted. "If they’re coming out of a smokestack or tail pipe, they’re regulated, but if they’re coming out of a dryer vent, they’re not."

The study did not specifically analyze health effects caused by the chemicals emitted from laundry vents, but Steinemann recommends using laundry products without any fragrance or scent.