Vehicles are one of the largest emitters of greenhouse gases but they have a rival when it comes to the worst causes of pollution, especially the pollutants in the ozone layer. A study from the National Oceanic and Atmospheric Administration shows that the chemical vapors that come from some industrial and consumer products might actually be doing more damage to the environment than those that come from fuel.

The chemical vapors called volatile organic compounds have reactions with chemicals in the air and the sun and end up causing ozone pollution and fine particulates in the air. Restrictions put on emissions that come from transportation sources have been successful in lowering the chemical vapors from those sources. This makes the vapors coming from other sources easier to discover and more important to study, said the research paper published in Science.

“As the transportation sector gets cleaner, these other sources of VOCs become more and more important,” the lead author on the study, Brian McDonald told NOAA. The chemicals come from everyday products like cleaning agents, pesticides, paint and even personal care products.

The difference between these pollutants and those that come from vehicles has to do with the amount of evaporation for each pollutant. The chemicals found in cleaning supplies and personal care products are actually designed to evaporate, according to NOAA, while products for transportation like gasoline are actually kept from evaporating.

A perfume is a good example; it’s designed to hang in the air so those around the wearer can actually smell it. This is completely different from fuel that’s contained and protected. Regulations like the Clean Air Act focused more on the pollution from transportation and the production of the fuel for those sources, but there’s no equivalent that regulates the personal products the pollute.

The study was conducted with data on Los Angeles, using the city as a case study location, but the researchers involved believe their findings would hold true for other urban settings as well. Measurements of emissions in Los Angeles didn't match calculated emissions so the researchers examined where else the discrepancy could come from.