When Meghan Rebuli, PhD, was in graduate school, she investigated the health effects of Bisphenol A (BPA), a chemical widely used in a variety of household products, including baby bottles. During that time, growing research showed BPA was harmful to humans, especially infants and children. As the public learned about this research, parents successfully demanded that BPA be removed from baby bottles. “In this country, we are often reactive. We wait until something bad happens before the government implements regulations,” she said. “With BPA, we saw how consumers have the power to demand change sooner than what is possible with government regulatory processes.”
Dr. Rebuli was moved by the knowledge that there are so many chemicals in everyday household products that we know little about. “I knew I wanted to help people make more informed decisions about their exposure to chemicals in the products they’re using, in order to improve their health,” she said.
She started researching e-cigarettes and found one of the primary factors that attract people to them is their flavoring, such as fruit or candy. “I became interested in other aerosol products that included similar flavoring or fragrance chemicals, and I landed on air fresheners,” she said.
What Is in Air Fresheners?
Air fresheners, such as plug ins, sprays or candles, are used by over 70% of the population of the United States to improve the smell of indoor spaces. “There is so much data on outdoor air pollutants even though we spend 97% of our time indoors. But we know so little about the effects of products we inhale indoors, such as air fresheners. People should be able to make choices about the products they use, knowing what the health impacts can be,” she said.
No studies have directly evaluated how air fresheners can affect lung health, so Dr. Rebuli is paving the way. With the help of an American Lung Association Indoor Air Award, the Assistant Professor of Pediatrics and Director of the Curriculum in Toxicology and Environmental Medicine at the University of North Carolina at Chapel Hill will lead a study on the effects of chemicals in popular air fresheners on airway cells.
“We know that people with asthma can have worsening breathing problems if they inhale air fresheners, but we don’t know exactly why,” she explained. She hopes to discover which products are irritating to the respiratory tract, potentially causing breathing problems.
This lack of knowledge is compounded by the fact that manufacturers don’t have to list the ingredients of air fresheners on the label. A key part of her research is determining which ingredients are in these products, and how much. “Some brands do list ingredients, while others simply say, ‘natural flavors,’” she said.
Dr. Rebuli and her team are starting their research by determining the top-selling spray air fresheners. They will buy about 20 different brands and scents, and use an instrument called a mass spectrometer to identify their chemical ingredients. Then, they will determine how much of each key ingredient is in each product.
Next, they will conduct test-tube experiments that expose cells that line the airways in cultures, or epithelial cells, to varying types of air fresheners. These cells are the lungs’ first line of defense, forming a protective barrier that guards the lungs against inhaled harmful microbes, allergens and air pollutants. Dr. Rebuli will look for signs of toxicity in the epithelial cells such as inflammation or altered cell function. “We plan to look at maintenance of the barrier between cells, function of cilia that grow on top of the cells that are used to push mucus up and out of the airway, cell cycle function, and markers of cell death, among other outcomes,” Dr. Rebuli explained.
Helping Consumers Make Safe Choices
Once she determines the makeup of popular air fresheners and how they affect airway cells, Dr. Rebuli wants to expand her research to understand the differences between people who do or do not use air fresheners. “Surveys have found that people who don’t use air fresheners say they dislike them because they cause headaches, nausea, respiratory irritation or coughing,” she said. “This suggests there may be more than just a preference in avoiding these products. Maybe some people have different cells receptors, or levels of receptors that react with chemicals in these products. Or they have a genetic mutation that makes them more sensitive to certain scents.”
Ultimately, the findings from this research could be used to formulate regulations that will ensure that the air fresheners on the market are as safe as they can be. “We need more information that will help the public make good choices about the products they are using in their homes,” Dr. Rebuli said. “There are so many other aerosol products we use indoors that may affect our breathing, from cleaning products to haircare products. We have a lot more work to do.”
Blog last updated: March 20, 2026
