Air fresheners affect more than just how your home smells; for people with asthma, they can trigger real breathing problems. Over 70% of Americans use air fresheners like plug-ins, sprays, or candles, but until recently, no one had systematically studied how these products affect lung health. Now, researchers are investigating which ingredients and formats pose the biggest risk, and the findings are reshaping what experts recommend for people with respiratory sensitivity.

What Exactly Triggers Asthma When You Use Air Fresheners?

For years, people with asthma reported that air fresheners caused headaches, nausea, respiratory irritation, or coughing. But the scientific explanation remained unclear. Dr. Meghan Rebuli, Assistant Professor of Pediatrics and Director of the Curriculum in Toxicology and Environmental Medicine at the University of North Carolina at Chapel Hill, is leading groundbreaking research to understand why.

"We know that people with asthma can have worsening breathing problems if they inhale air fresheners, but we don't know exactly why," explained Dr. Rebuli. "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."

Dr. Meghan Rebuli, Assistant Professor of Pediatrics and Director of the Curriculum in Toxicology and Environmental Medicine, University of North Carolina at Chapel Hill

Dr. Rebuli's research, funded by an American Lung Association Indoor Air Award, will test how chemicals in popular air fresheners affect airway cells. Her team plans to buy about 20 different brands and scents, use a mass spectrometer to identify their chemical ingredients, and then expose lung cells to these products in laboratory conditions. They'll look for signs of inflammation, altered cell function, and damage to the protective barrier that lines the airways.

One major problem complicating this research: manufacturers don't have to list air freshener ingredients on the label. Some brands disclose their components, while others simply say "natural flavors" without any specifics. This lack of transparency means consumers and researchers alike can't easily identify which chemicals they're breathing in.

Which Air Freshener Formats and Chemicals Pose the Highest Risk?

Not all air fresheners affect asthma equally. The format, concentration, and duration of exposure all matter significantly. Research and expert analysis have identified four key factors that trigger asthma symptoms in sensitive individuals:

• Aerosol sprays: These deliver fragrance as a fine, suspended particulate cloud that can be inhaled deeply into the lower airways. The burst pattern creates high concentration in seconds, giving lungs no time to adapt, making aerosols the highest-risk category for most asthmatics.
• Volatile organic compounds (VOCs): Many plug-in air fresheners and strong gels emit VOCs, which can include formaldehyde, benzene-family compounds, phthalate carriers, and synthetic musks. Independent indoor air-quality studies have linked sustained VOC exposure to respiratory irritation in sensitive populations.
• Undisclosed fragrance mixtures: The regulatory term "fragrance" on a label can cover dozens of distinct chemical compounds, some of which are documented respiratory irritants. You can't avoid what isn't named.
• Chronic continuous exposure: Even a mild fragrance becomes a respiratory load problem if it runs 24 hours a day in a small space. Plug-in air fresheners in poorly ventilated rooms create sustained exposure that your lungs never recover from.

The key insight from experts is that asthma triggers aren't about whether a fragrance is "natural" or synthetic. Instead, the risk depends on respiratory load, which means how much airborne stimulation your lungs have to process and for how long.

How to Reduce Your Respiratory Load From Air Fresheners

• Switch to odor absorbers: Activated charcoal sachets, bamboo charcoal bags, or open dishes of baking soda absorb odors without releasing any compound into the air, creating zero respiratory load and zero fragrance triggers. Refresh charcoal in sunlight every 2 to 4 weeks; replace baking soda every 30 days.
• Choose slow-release formats: Wood or wax-based diffusers deliver fragrance through gradual evaporation rather than a powered burst, keeping respiratory load low because release rate is constrained by surface area, not mechanical projection.
• Avoid aerosol sprays entirely: If you have asthma, remove aerosol air fresheners from your home first. The burst pattern and deep airway delivery make them the most direct trigger mechanism.
• Test your tolerance: The honest test is whether you can sit in your space for 60 minutes with the fragrance running and notice no change in your breathing. If you feel any tightness, dryness, or want fresh air, the product is too much for your respiratory system.
• Consider HEPA air purification: For severe asthma, an unscented HEPA air purifier actively filters airborne particulates and improves air quality without adding any fragrance load, though this approach costs more and provides no scent.

The honest conversation about air fresheners and asthma isn't about natural versus synthetic ingredients. It's about understanding your individual respiratory sensitivity and choosing formats and concentrations that your lungs can tolerate over time.

What Does This Research Mean for Regulation and Consumer Choice?

Dr. Rebuli's findings could eventually inform regulations that ensure air fresheners on the market are as safe as possible. Currently, the industry operates with minimal oversight compared to other consumer products. Her research will identify which specific products and ingredients are most irritating to the respiratory tract, potentially causing breathing problems.

"We need more information that will help the public make good choices about the products they are using in their homes," stated Dr. Rebuli. "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."

Dr. Meghan Rebuli, Assistant Professor of Pediatrics, University of North Carolina at Chapel Hill

The research also hints at a deeper question: why do some people react to air fresheners while others don't? Dr. Rebuli plans to expand her work to understand whether people who avoid air fresheners have different cell receptors, different levels of receptors that react with fragrance chemicals, or genetic mutations that make them more sensitive to certain scents.

For now, the takeaway is clear. If you or someone in your household has asthma, the safest approach is to test your individual tolerance, avoid high-risk formats like aerosols and continuous plug-ins, and consider whether odor absorption or slow-release formats work better for your respiratory health. And if you have moderate or severe asthma, discussing air freshener choices with your doctor or pulmonologist is a smart step before making changes.