Dogs, cats, rabbits: How Our Pets Affect the Air We Breathe
The presence of a pet profoundly changes the composition of indoor air : persistent biological allergens, resuspended particles, altered microbiome. These effects add to indoor air that is already five to seven times more loaded with pollutants than outdoor air. For sensitive individuals, understanding these mechanisms is the first step toward addressing them without necessarily having to part with the animal.
In February 2026, a Radio France article reported that the presence of a dog significantly modifies the microbiological and particulate composition of indoor air. The observation aligns with something many people have felt without being able to explain it: the air in an apartment with an animal is different, heavier, biologically denser, sometimes more irritating for the respiratory tract.
The question is not whether one should or should not have a pet. It is about understanding what its presence concretely changes in the air we breathe and how to respond to it effectively.
Which animals affect our indoor air?
Animals do not pollute the air in the industrial sense of the term. However, some modify it more than others.
- The cat is the pet whose allergenic impact is the most documented. It produces Fel d 1, a protein secreted by its sebaceous and salivary glands, carried by very fine particles that remain suspended for a long time. This allergen is particularly persistent: studies have detected its presence in homes that have never housed a cat, transported by clothing or visitors.
- The dog produces Can f 1, found in its saliva and dander. Its impact is twofold: allergenic on the one hand, and mechanical on the other, as its movements disturb floors and resuspend settled particles. One study (Qian et al. Indoor Air, 2012) documented this role as a particulate vector.
- Rodents and rabbits produce urinary allergens (notably Mus m 1 for the mouse) which, although less known to the general public, can trigger significant respiratory reactions in sensitive individuals.
- Birds generate feather dust and dander that accumulate in the air, particularly in the rooms where they live.
What animals actually introduce into the air
Airborne and persistent allergens
Animal allergens are carried by small particles often smaller than 5 micrometers, with a significant fraction below 2.5 micrometers. This is what makes them difficult to remove: at this size, they remain suspended for a long time, penetrate deeply into the respiratory tract, and attach to the fine particles already present in the air.
A study (Custovic et al. Clinical & Experimental Allergy, 1998) showed that Fel d 1 remained detectable in homes without cats for several months. The EPA confirms that these allergens travel, settle in textiles and on surfaces, and disperse again into the air with every movement.
Resuspended particles
An active animal in an apartment acts as a mechanical vector: it lifts settled dust, carries outdoor particles on its fur (pollens, spores, urban pollution particles) and redistributes them indoors. This particle agitation is continuous and difficult to control through ventilation alone.
A modified microbiome
A study by Fujimura et al. (PNAS, 2010) showed that the presence of a dog enriches the indoor microbiome with greater bacterial diversity. Some research suggests a potentially protective effect against childhood allergies, within the framework of the hygiene hypothesis. However, this effect depends on genetic background and does not offset the allergenic load for people who are already sensitized.
Why ventilation is not enough
ANSES is clear on this point: ventilation is essential, but insufficient when the source is internal and continuous. A pet creates exactly this type of source: permanent, renewed every hour, distributed throughout every room.
Unlike outdoor pollution, which is intermittent and can be reduced by closing windows during peaks, animal allergens settle into textiles and surfaces, and are redistributed into the air with every movement. Opening the windows for ten minutes a day renews only a fraction of the air, without affecting what is trapped in surfaces, nor what the animal continuously produces.
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Does the air around your home contain pollutants? How has it changed in recent months? Is there a risk to your health?
Do I need an air purifier if I have pets?
For people who are not allergic, an air purifier is not essential, but it improves overall air quality in a home with pets.
For people with allergies or asthma, the answer is clearly yes. The AAFA and the EPA explicitly recommend the use of an air purification system, in addition to other measures, including keeping the animal out of the bedroom, regular cleaning, and washing textiles.
The question then becomes choosing the right technology.
Traditional HEPA filter purifiers capture airborne particles in a filter. Their limitation: the filter becomes loaded and loses efficiency over time, requires regular replacement (€50 to €150 per year), and can release into the air some of what it has retained at the end of its lifespan.
Ionizer-type air purifiers work differently, inspired by a natural process. In environments rich in negative ions (forests, seaside areas, the aftermath of thunderstorms), the air naturally regenerates: negative ions attach to airborne particles, electrically charge them, make them heavier, and cause them to fall to the ground. An ionizer reproduces this natural depollution mechanism continuously. It is particularly effective on fine and ultrafine particles that conventional filtration reaches less effectively—those same particles that carry a significant fraction of animal allergens. Without filters, without noise, with a consumption of 0.5 W.
Testimonials
The ionizers run 24/7 in the cat hotel. What I notice today is that the air in the hotel is always pleasant. Despite the constant presence of cats, the hotel always smells like new wood. Customers find it very pleasant. I don't know if it comes from the ionizers, but I find the air soothing.
Every year, I had to treat my horse Jesonn with medication. He had trouble entering his stall, I could only ride him for an hour, and wetting his hay had become routine. I installed a Teqoya purifier. Within a few weeks, Jesonn regained his vitality: he enters his stall without difficulty, breathes better, and his neighbors benefit as well.
From the first days we felt a clear improvement in our breathing, as if the surrounding air were lighter, with faster falling asleep [...]. In addition to particles being quickly eliminated, the odors of smoke, cooking, mold, and animals disappear quickly to make way for pure and pleasant air.
How to limit the impact of pets on air quality
The bedroom deserves special attention: this is where exposure lasts the longest, and where keeping the animal out is the most effective measure.
In living areas, regular cleaning of textile surfaces, vacuuming two to three times per week, and brushing the animal outdoors when possible reduce allergen reservoirs. Washing hands after contact with the animal completes these measures.
For airborne particles—what floats before being breathed in—a continuously operating purification system acts where cleaning alone is not enough.
FAQ
Which animals affect indoor air the most?
The cat is the animal whose allergenic impact is the most documented, due to the persistence and mobility of its main allergen (Fel d 1). Dogs generate both allergens and mechanical agitation of particles. Rodents and birds produce allergens that are less known but just as real for sensitive individuals.
Do I need an air purifier if I have pets?
For people with allergies or asthma, yes. Recommendations from the AAFA and the EPA explicitly include an air filtration system. For people without allergies, a purifier improves overall air quality without being essential.
Do cat or dog allergens disappear if the animal leaves the home?
No, not immediately. Animal allergens are extremely persistent: Fel d 1 remains detectable for several months after the animal leaves. Deep cleaning of textiles and surfaces, combined with continuous air purification, speeds up their removal.
Is it safe to sleep with an air purifier running all night when you have a pet?
Yes, and it is even recommended. Nighttime is when exposure to allergens lasts the longest. An ionizer operates silently, consumes 0.5 W, and requires no supervision. Simply make sure that the chosen model is certified as producing no ozone.
Which air purifier should you choose when you have a pet?
For animal allergens, ionizers are particularly suitable: they act on fine and ultrafine particles that carry these allergens, without filters to maintain.
Does a dog enrich the microbiome of a home?
Yes. Scientific studies (Fujimura et al., PNAS, 2010) show that the presence of a dog enriches the indoor microbiome. Some research suggests a protective effect against childhood allergies. This effect remains dependent on genetic background and does not offset the allergenic load for people who are already sensitized.
In summary
Pets profoundly modify indoor air: persistent airborne allergens, resuspension of fine particles, and changes to the microbiome. In air that is already five to seven times more polluted than outdoor air, these contributions add to an existing burden. For sensitive individuals, the challenge is not to remove the animal, but to act on the air continuously, not only on surfaces.
Useful sources
- WHO — WHO guidelines for indoor air quality
- EPA — Indoor Air Quality
- ANSES — Indoor Air Quality
- Custovic et al., Clinical & Experimental Allergy, 1998
- Fujimura et al., PNAS, 2010
- Qian et al., Indoor Air, 2012
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