People's sense of smell is extremely powerful at evoking nostalgia. A simple whiff of the right air freshener has the power to act like a time machine, transporting someone back to a treasured memory that took place decades earlier.
It's no wonder then that the global fragrance market exceeded $56 billion in 2024, and is projected to reach nearly $75 billion by 2030. Between nostalgia -- or the less glamorous function of covering up unpleasant smells -- it's no wonder there are thousands of options when it comes to air freshener sprays, melts, diffusers, gels and plug-ins. The issue, though, is that product development and marketing far outpaces safety science, explained Kevin M. Stewart, director of environmental health advocacy and public policy at the American Lung Association.
An array of more than 3,000 different chemicals are used in fragrance products in the United States, even though many of these ingredients have never been tested for long-term impact on human health.
"We don't know what happens when people are exposed to some of these chemicals chronically over years or decades," Stewart said.
The early correlations between fragrance chemicals and health impacts are alarming. Peer-reviewed studies show links between air fresheners and neurological harms, including interfering with the brain's communication to the heart. Other research shows correlation between fragrance products and certain cancers, hormone disruption, birth defects, obesity and reproductive problems, among other ills.
The Lung Association notes that scented products emit more than 100 volatile organic compounds, which can react with the air and create secondary pollutants like formaldehyde. The Consumer Product Safety Commission does not require manufacturers to list individual ingredients used to create fragrances on the label, so you may not even know that you are in danger. Products marketed as "green" and "natural" can also be misleading for this reason, Steward warned.
What is very clear and established in the medical literature, however, is the harmful effects that air fresheners have on people with allergies and asthma.
Research shows that nearly 65% of asthmatics are negatively impacted when exposed to fragranced products. This takes the form of breathing difficulty, migraine headaches and asthma attacks. More than 40% are triggered by air fresheners or deodorizers. Despite this, 99% of asthmatics are exposed to fragranced products at least once a week, including places like school and the workplace - places where they cannot control the environment.
Fragrances, which impact different people in different ways, and can also trigger eye irritation and a runny nose. "Someone may be 100 times more sensitive to a chemical vs another person who isn't bothered," Stewart said.
That's why he said it's especially important for places like schools and workplaces to adopt fragrance-free policies. (The American Lung Association offers information and programs like the Clean Air School Challenge to aid in this.)
"I want everyone to remember that not everyone's body reacts the same way to fragrance problems," Steward explained. "Just because you enjoy the smell, someone else might be experiencing health effects.
"It's not just about you, one person, but understanding the reality that a teacher in a classroom may like the smell of the products, but there are students in the classroom who might have asthma who might have health consequences that impact their learning," he added.
For more information, check out the American Lung Association's Clean Air at School Program and its Sample Fragrance-Free Workplace policy.