Takeaway
To improve indoor air quality, counsel patients to combine source control with filtration. This includes eliminating smoking/vaping and avoiding fragrances like scented candles/incense. Recommend air cleaners with HEPA and carbon filters.
Lifelong Learning in Clinical Excellence | December 22, 2025 | 2 min read
By Meredith McCormack, MD, MHS, Johns Hopkins Medicine
Kim is a patient with asthma who had a difficult autumn and is especially interested in staying healthy over the holidays. “Will an air cleaner help me breathe better?” she asked during her recent clinic visit.
Kim has already done a lot to help her asthma. In addition to taking her medications, she’s been thoughtful about her home environment. Due to allergies, Kim doesn’t have pets and has taken big steps to get rid of pests in her home. We realized she was allergic to guinea pigs after their family volunteered to keep the class pet for the holidays a few years ago. She also has allergies to cats, dogs, and mice. She no longer has pets and changed the carpet in her bedroom to hard surface flooring. She uses pest management to keep mice and cockroaches out and keeps the food in her kitchen in sealed containers to maintain a pest-free home. These changes have helped her asthma.
To answer her question about air cleaners, I shared with Kim results from BREATHE Center studies that have investigated indoor air quality and the impact of air cleaners. Our studies have consistently shown that air cleaners can reduce indoor air pollution by about 50%, cutting the levels in half. This has translated into improvements in lung health for children with asthma and adults with COPD. Kim has a son with asthma and a mother with COPD—lowering levels of indoor air pollution helps everyone in their household. The best choices are air cleaners that include HEPA filters and carbon filters.
What else can we do to improve indoor air quality? We can target the sources. These include cooking foods on the stovetop. Using the back burner and turning on the vent can reduce air pollution from cooking exhaust. Smoking and vaping are also contributors, and home smoking bans are a powerful way to protect health. Candles and incense are also sources of indoor air pollution. In addition to the smoke, the scents contain volatile organic compounds (VOCS) that may have their own health risks. While certain scents have sentimental connotations around the holidays or are considered fresh or clean, truly “clean air” is fragrance free! BREATHE Center studies have ongoing studies to understand the effects of the complex chemicals that are in our everyday environment.
Simple steps to make the home environment healthier:
1. Support home smoking and vaping bans to protect family and friends.
2. Avoid scented candles, incense, and fragrances. Clean air is fragrance free!
3. Use back burners and the vent when cooking on the stove.
4. Store foods in sealed containers and keep food in the kitchen and dining area. Mice and cockroaches are not our guests!
5. Air cleaners with HEPA filters (and carbon filters) reduce indoor air pollution.
6. Remember to change the filter to central heating systems and portable air cleaners as directed.
The home environment can help promote health, and simple steps can reduce harmful exposures to protect family and friends.
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This piece expresses the views solely of the author. It does not necessarily represent the views of any organization, including Johns Hopkins Medicine.