Air purifiers prove effective in removing house dust mite, cat, dog allergens


Buters reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.

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Portable air filtration devices with adequate clean air delivery rates can effectively remove mites, cat and dog allergens and particulate matter from ambient indoor air, according to a study published in Clinical and Translational Allergy.

The researchers called it the most extensive study focused on portable air filtration efficiency targeting a range of airborne features in bedrooms.

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“Two years before the study, several researchers from Europe and I had a scientific meeting with Philips on air quality and allergies,” Jeroen Buters, PharmD, toxicologist and deputy director of the Center of Allergy & Environment and member of the German Center for Lung Research at Technical University and Helmholtz Center in Munich, told Healio.

Philips then asked Buters and his colleagues if they could investigate whether one of the company’s air purifiers also functioned with allergens, Buters said.

The researchers examined the Dermatophagoides pteronyssinus Der p 1 and Dermatophagoides farinae Der f 1 house dust mite allergens, Fel d 1 cat allergen and Can f 1 dog allergen, all of which can be detected in airborne particulate matter (PM).

“Everybody thinks Dermatophagoides pteronyssinus is the main allergen-producing mite in homes. It is not — at least not in Munich, probably also not in other places. There, it is Dermatophagoides farinae, another closely related mite. Almost all patients get treated with D pteronyssinus extracts. Due to the high similarity between them, that is mostly okay,” Buters said.

“In addition, life conditions for each mite are different, so you better know which one you are talking about. Indeed, in Munich, more individuals are sensitized against D. farina than D. pteronyssinushe continued.

Portable air purifiers (Philips Air Purifier AC4236, 4000i series) with high-efficiency particulate air filters and clean air delivery rates of 500 cubic meters per hour were placed in 22 bedrooms in Bavaria, Germany, between Feb. 5 and April 22, 2020, and between July 1 and Sept. 28, 2020.

Researchers conducted control and intervention visits 4 weeks apart at each home. During the intervention visits, they spent 30 seconds shaking pillows, 30 seconds shaking bed covers and 60 seconds shaking sheets to represent dust disturbance events.

Additionally, the researchers measured Der f 1 concentrations in the living rooms of four homes and found the median concentration was 63.2% less compared with bedroom concentrations.

“An Australian study found the majority of allergens in living room couchs. We did not. We found it in beds. That’s probably an Australia-Europe gradient,” Buters said.

Immediately after each event, the researchers turned on the purifier and ran it for 1 hour. This process was repeated four times during each visit for a total of 4 hours of sampling per home. The researchers then examined the content collected in the filters.

There were qualifying amounts of Der f 1 in 20 homes, Der p 1 in four homes, Can f 1 in 10 homes and Fel d 1 in 21 homes, even though only three homes had a cat and two homes had a dog.

“In almost all studies, some homes do not have mite allergens. With our good methods, we found the allergen everywhere,” Buters said, noting that there was also a surprising amount of cat allergen.

“Only three out of 22 homes had a cat, but still cat allergen was everywhere,” Buters said. “And homes with a cat were not always the ones with the most cat allergen.”

With air filtration, the researchers said, there was a statistically significant reduction in total airborne Der f 1 (P < .001), but the reduction in Der p 1 was not statistically significant. Also, median reduction was 75.2% for total Der f 1 and 65.5% for total Der p 1.

The air filtration also significantly reduced total Fel d 1 (P < .01 (with a 76.6% median reduction and total Can f 1 )P < .01) with an 89.3% median reduction.

The homes that had a dog had a median Can f 1 count of 219 pg/m3 during the control visits compared with 22.8 pg/m3 for homes that did not have a dog. During the intervention visits, the homes with a dog had a median Can f 1 count of 19.7 pg/m3while those without a dog had a median count of 2.6 pg/m3.

During the control visit, the homes with a cat had a median Fel d 1 count of 50.7 pg/m3 and those without a cat had a count of 5.1 pg/m3. During the intervention visit, the homes with a cat had a count of 35.2 pg/m3and those without had a count of 0.9 pg/m3.

“Purification went surprisingly fast — about 10 to 15 minutes for a bedroom,” Buters said.

Most of the Der f 1 and Der p 1 was detected in PM that was greater than 10 microns in width (PM>10) or between 2.5 and 10 microns wide (PM2.5-10). Most of the cat and dog allergens were associated with PM in these sizes as well.

Also, there was a significant reduction of Can f 1 in all PM sizes that had measurable concentrations of allergen, with medians in reductions of 87.5% for PM>10 (P < .01) and 93.7% for PM2.5-10 (P < .01).

While smaller particles with allergens stay airborne longer and are more likely to be inhaled compared with larger particles, the researchers said, air filtration also more efficiently removes smaller particles, making air filtration an effective strategy to remove allergens and minimize exposure.

“Reducing allergens is a pain in the neck, but it will make allergic individuals feel better. This method for allergen removal is easy,” Buters said, noting that reducing cat allergens, which he called the fourth most important allergen, is particularly difficult.

“You can wash the cat — good luck — or get rid of the cat,” he said. “I know of no other method to remove cat allergen. Air filtration does.”

Next, the researchers will examine whether patients with allergies can sleep better with air purifiers.

“According to our results, they should. But as scientists, we want proof first,” Buters said.

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Jeroen ButersPharmD, can be reached at

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