It found them. As she recently told me, there were far more VOCs in the air than she expected—and many more, specifically, than could be explained just through car exhaust. What was releasing them?
In a new study, published this month in the journal Science, a team of researchers including Gilman propose an answer. They find that a wide range of household goods—such as paints, printing inks, cleaning products, fragrances, nail polishes, and hair sprays—now emit about as many VOCs as cars do in U.S. cities.
That has potential implications for public health—and for how the government protects it. As air pollutants go, VOCs are kind of the ack of all trades. While some of them are toxic, causing irritation and headaches and nausea by themselves, even nontoxic VOCs can be unhealthy. When exposed to another type of air pollution, VOCs produce ozone, which can trigger asthma attacks. And when VOCs are exposed to sunlight, they produce particulate matter, which is linked to heart attacks and premature death.
The list of products that produce VOCs is staggeringly long. “The type of products are pretty much everything you would think of if you look under the kitchen sink, on the shelf in your garage, or in your bathroom,” says Gilman. “They’re soaps, shampoos, lotions, cleaning products, as well as degreasers, adhesives, ink, house paints.”
One common word found in many ingredients lists is a likely indication of VOC-emitting chemicals. “You see a single word, fragrances—with that one label, there’s up to 2,000 different VOCs that could be listed as a fragrance,” she says.
Two popular fragrances are limonene and beta-Pinene, which smell like lemons and pine trees, respectively. Though both occur in nature, they also produce VOCs when used at high concentrations, like in cleaning solution or a car air freshener.
“Traditionally, we think of the transportation sector as the main source of urban air pollution. But as the transportation sector has gotten cleaner in response to things like the Clean Air Act, other sources of emissions are becoming more important in a relative way,” says Brian McDonald, the lead author of the study and another research chemist at NOAA.
“You don’t have to use a lot of consumer products to emit a significant fraction of these VOCs,” he adds.“What this means is that the person in the car—and all the products they use in the morning—is now as big a source of VOCs as what comes out of the tailpipe as they drive to work.”
To be clear, the idea that household products could trigger air pollution isn’t new. Many household products contain ingredients produced by refining crude oil, and researchers have known that these ingredients could off-gas VOCs for decades.
They just thought these ingredients caused fairly little pollution—and much less, certainly, than cars did. They cited data showing that 95 percent of crude oil is refined into fossil fuel, while only about 5 percent of it becomes an ingredient in some kind of household product.