You might not think twice about the fresh scent of pine or the calming aroma of lavender filling your home.

After all, these fragrances are meant to create a clean and inviting space.

But could the very products designed to enhance your indoor environment be doing more harm than good?



According to Purdue engineers, many scented products release volatile chemicals that, when exposed to ozone, undergo a chemical reaction that creates nanoscale particles—so small that they can enter deep into the lungs and even spread to other organs.

The research, led by Assistant Professor Nusrat Jung and Professor Brandon Boor, is the first of its kind to study how these particles form indoors and how they compare to pollutants found outside.

Using Purdue’s tiny house lab—a specially designed space that mimics a real home but is equipped with cutting-edge air quality monitoring technology—the team was able to track these invisible pollutants in unprecedented detail.

"To understand how airborne particles form indoors, you need to measure the smallest nanoparticles—down to a single nanometer," explained Boor, Purdue's Dr. Margery E. Hoffman Associate Professor in Civil Engineering.

"At this scale, we can observe the earliest stages of new particle formation, where fragrances react with ozone to form tiny molecular clusters. These clusters then rapidly evolve, growing and transforming in the air around us."

Their findings challenge the long-held assumption that indoor air is safer than outdoor air, showing that even the most common household products can contribute to pollution levels comparable to—or even worse than—what’s found outside in urban environments.



What they found was alarming: The scented products we use every day—air fresheners, wax melts, and essential oil diffusers—aren’t just releasing pleasant aromas.

They are actively changing the air chemistry inside our homes, producing nanoparticles at levels comparable to car exhaust and gas stoves.

Unlike visible dust or smoke, these nanoparticles are just a few nanometers in size—thousands of times smaller than a grain of sand.

Because of their microscopic size, they can bypass the body’s natural defenses, travel deep into the respiratory system, and potentially cause health issues.


The study found that within just 20 minutes of using a typical air freshener or wax melt, between 100 billion and 10 trillion of these nanocluster aerosol particles could deposit into a person’s lungs.

While researchers are still working to understand the long-term health effects, the sheer volume of these particles raises concerns about potential respiratory risks.

While researchers have yet to discover how these volatile chemicals could impact our health, they cautioned that their presence alone suggests a need for further study and awareness.

What’s even more surprising is that these levels match or even exceed the number of particles released by cooking with a gas stove—another well-documented source of indoor air pollution.



A study led by Purdue researchers found that cooking on a gas stove emits vast amounts of nanoparticles, with just 1 kilogram of cooking fuel releasing 10 quadrillion particles smaller than 3 nanometers.

This means that standing in a kitchen while cooking on a gas stove could expose someone to 10 to 100 times more of these tiny airborne particles than they would encounter from car exhaust while standing on a busy street.

However, what’s even more alarming is that heavily scented products, such as air fresheners, wax melts, and essential oil diffusers, match or even surpass gas stoves and car engines in generating these nanoparticles.

The Purdue study found that within just 20 minutes of exposure to these products, between 100 billion and 10 trillion nanocluster aerosol particles could settle into the respiratory system—comparable to or worse than what’s inhaled from cooking emissions.



The fact that everyday household fragrances can produce pollution levels on par with major combustion sources raises important questions about how safe our indoor environments really are.

While many are now aware of the concerns surrounding gas stoves and their impact on air quality, this research suggests that the very products designed to make our homes feel fresher may be creating an even greater hidden risk.

Want to learn more about how air quality affects your well-being? Read here.

Read more: Everyday household items could be harming your health—here’s how to stay safe
Have you ever noticed respiratory discomfort after using scented products? What steps do you take to improve air quality in your home? Share your thoughts and experiences in the comments below!