If you’ve shopped for paint or bought a crib or mattress or new flooring, you might have seen a GREENGUARD Certification mark on the product packaging. But what does it mean, exactly, and how can it help you enjoy cleaner indoor air?

SafeBee talked to the folks at UL, which issues GREENGUARD Certification, to find out what’s behind the label.

All about emissions

UL certification greenguardIf a product has been GREENGUARD Certified, it has been tested and scientifically proven to have low chemical emissions, says Scott Steady, product manager for indoor air quality at UL Environment. In other words, it’s guaranteed to give off only low levels of volatile organic compounds, or VOCs.

VOCs are carbon-based chemicals (such as formaldehyde) that easily become vapors or gases. Mattresses, flooring and even wall paints give off VOCs. They’re responsible for that new building smell and new car smell, Steady says. Inside your house you may be breathing anywhere from 50 to hundreds of different VOCs at any time.

Indoor air can be two to five times more polluted than outdoor air, according to the Environmental Protection Agency. “We look at the air — it’s empty space, but there are hundreds of chemicals floating around at low levels in our space. Those chemicals are in every breath,” says Steady. (Photo: Courtesy of UL Environment)

Related: Clearing the Air: 3 Dangerous Pollutants in Your Home

Testing, testing

A peek at the testing chambers used by GREENGUARD is eye opening. These polished stainless steel compartments — some as large as rooms — are known as dynamic environmental chambers. They are temperature and humidity controlled “so there’s no background level of VOCs,” Steady says. Inside these chambers go furniture, laptops, space heaters, humidifiers, flooring, insulation and anything else GREENGUARD tests.

Small table in testing chamber(Photo: Courtesy of UL Environment)

“We have over 100 chambers ranging from about the size of a small oven up to a full room-size chamber for a crib or queen-size mattress,” Steady says.

As the product sits in the chamber, UL measures the emissions. “Our chemical analysts can see between zero and 200 or 300 chemicals coming out of a product.”

Some items, such as building products and furniture, sit in a chamber for two weeks. They off-gas the most chemicals on day one, and the levels decay over time, Steady says. After a few weeks, they reach a steady emissions rate.

Other items, such as electronics, stay in the chamber for only a day. “Electronics have some emissions before plug-in,” Steady says, “but they get hot as they operate. That heat generates the emissions, so we measure as they heat up.”

From start to finish, the certification process takes about one to six months, depending on the complexity of the product, says Steady. Thousands of products a year go through some sort of testing. And once an item has GREENGUARD Certification, a new version of that item is retested each year.

Crib in testing chamber(Photo: Courtesy of UL Environment)

Related: 8 Ways to Have Cleaner Indoor Air This Winter

Products for kids’ rooms and schools

GREENGUARD Certification means the product has met industry standards for low emissions, but anything designed for a child’s room or educational setting has to meet even stricter standards, Steady says. GREENGUARD Gold Certification means products “emit even lower levels and incorporate a really low level of formaldehyde emissions specifically,” Steady says.

“Kids are more susceptible to indoor air quality problems. They breathe more per body weight, so they get a bigger dose of whatever’s in the air.”

To find certified products, go to UL’s Sustainable Product Guide to search through more than 13,000 GREENGUARD Certified items.

Related: Do You Really Need to Clean Your Air Ducts?

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Angela is a Pulitzer Prize-winning digital editor with more than 15 years of experience delivering news and information to audiences worldwide. Prior to joining SafeBee, she was the features editor for Boston.com at The Boston Globe, overseeing health, travel, entertainment, business and lifestyle coverage. Before moving to features, she was the news and homepage editor, covering stories such as the Boston Marathon bombing, Red Sox World Series victories, presidential elections, a papal inauguration, and more. Her favorite safety tip: Clean your phone! The average cell phone has 18 times more germs than the toilet handle in a men’s restroom.