A new study finds that shampoo, moisturizers, colognes and other household products people use every day cause just as much smog as the exhaust spewing out of car and truck engines on the streets and highways.

The study, by the National Oceanic and Atmospheric Administration and UC Davis, establishes a stronger link than ever before between air pollution and lotions, perfumes, hair sprays and other grooming products, along with such items as household cleaners and paint.

“To a large extent, anything scented is going to contribute,” said Christopher Cappa, a professor of civil and environmental engineering at UC Davis and co-author of the study.

Cappa and his colleagues said the amount of petroleum in fuel is far greater — about 15 times more by weight — than lotions, paints and other household products. But the fuels used in cars are much cleaner than they used to be, meaning fewer smog-producing pollutants waft into the air in the exhaust.

“When we use these other products, a lot more of the volatile organic compounds end up in the atmosphere,” Cappa said. “In the case of perfumes, the purpose is to create odors, so when you put it on your body, the molecules are also in the room around you. And what’s inside gets outside. It doesn’t really go away.”

Ultimately, he said, the volatile organic compounds, or VOCs, react with sunlight and produce ozone or particulate matter, the building blocks of smog, which can damage people’s lungs.

The research team, led by Brian McDonald, a scientist in the Cooperative Institute for Research in Environmental Sciences at the University of Colorado, in Boulder, took atmospheric chemistry measurements in Los Angeles and compared those to indoor air quality measurement data.

They found that emissions from vehicles had been overestimated while industrial products emitted two or three times more compounds than previously thought. The Environmental Protection Agency estimates that 75 percent of VOC emissions come from vehicles while 25 percent is produced by household products. The new study put the split closer to 50-50.

“Gasoline is stored in closed, hopefully airtight, containers, and the VOCs in gasoline are burned for energy,” said Jessica Gilman, an atmospheric scientist with the NOAA’s Chemical Sciences Division. “But volatile chemical products used in common solvents and personal care products are literally designed to evaporate.”

It is a problem with no easy solution, Cappa said.

“A starting point would be to think about using less,” he said. “Beyond that, it’s going to take some more thinking.”

The report is being published Friday in the journal Science.

Cappa said researchers knew that paints and glues contributed to smog, but nobody had done a study analyzing the cumulative effect on air quality of all the household consumer products. The results were surprising even to the researchers, he said.

“This is not necessarily good,” he said. “It’s not like we were totally ignorant of this idea, but it’s worse than we thought.”

Note: An earlier version of this story mischaracterized the range of household products included in the study.