What's in my air
Pet dander — the allergen that stays airborne, and where filtration earns its keep
Pet dander is the shed skin, saliva proteins and sebaceous secretions of animals — with the principal cat allergen, Fel d 1, notable for being small, sticky and persistently airborne.
Limits and standards
India's NAAQS are ambient (outdoor) standards, and there is no statutory Indian indoor air quality standard for homes. WHO's guideline values are health-based targets rather than regulatory limits, and are consistently stricter.
| Standard | Limit | What it means |
|---|---|---|
| India | No regulatory standard | — |
Where it comes from
Cats
Fel d 1 is produced in sebaceous and salivary glands and spread across the coat by grooming. It is the most persistent common indoor animal allergen.
Dogs
Can f 1 and related proteins from skin and saliva. Generally less persistent airborne than cat allergen but the same principles apply.
Passive transfer
Cat allergen is carried on clothing into homes and schools with no cat. It is routinely detected in cat-free buildings.
Soft furnishings
Upholstery, carpets and bedding accumulate allergen and release it when disturbed.
Why it matters
- Pet allergen is a common trigger for allergic rhinitis and asthma, and the exposure is continuous rather than seasonal.
- The persistence is what surprises people: allergen remains detectable in a home for many months after a cat is removed, so 'rehoming the cat' does not produce immediate relief.
- It is one of the few allergens where air filtration has a strong mechanistic case, because the particles stay airborne long enough to be captured.
Note
Can you detect it yourself?
Consumer air quality monitors are genuinely useful for tracking change and poor at absolute measurement. Knowing which of the two you are looking at prevents most of the disappointment in this category.
| Question | Answer |
|---|---|
| Can you sense it? | Symptoms rather than perception. Onset within minutes of entering a home with a cat is characteristic. |
| What a consumer monitor shows | No consumer monitor detects specific allergens. Particle counts rise with pet activity but tell you nothing allergen-specific. |
| Field test | Clinical allergy testing identifies the specific animal allergen, which matters when a household has more than one pet and is deciding what to change. |
What removes it
Effectiveness ratings below describe the technology working correctly, within its service life, on water or air that suits it. “Depends” means there is a condition in the caveat that decides the outcome — read it before buying.
- HEPA air purifier in the bedroomEffective
Because the particles remain airborne for hours, filtration removes a genuine share of what would otherwise be inhaled. This is the allergen where a purifier earns its place.
- Pet-free bedroomEffective
Keeping the bedroom permanently pet-free, door closed, is the highest-impact single measure. Allergen still arrives on clothing, but at a much lower rate.
- Regular pet washingPartial
Reduces surface allergen load. The effect is real but short-lived and requires consistency to matter.
Caveat: Weekly washing is often impractical, and the benefit fades within days.
- Removing carpets and reducing upholsteryPartial
Removes the reservoirs that release allergen when disturbed. Hard floors that can be wet-mopped are considerably better.
- Sealed-system HEPA vacuumingPartial
Removes settled allergen. An unsealed vacuum redistributes it into the air, which is worse than not vacuuming.
What does not work
Each of these is commonly assumed — or actively marketed — to help with pet dander. None of them do.
'Hypoallergenic' breeds
No breed is free of the allergen. Individual animals vary in how much they produce, but breed is not a reliable predictor and buying on that basis frequently disappoints.
Ionisers
Deposit allergen onto surfaces, from which it is resuspended by movement.
Ozone generators
Do not denature allergen proteins at concentrations safe to occupy, and add a pollutant.
Air fresheners
Mask nothing relevant — the allergen is not the smell.
Source control that beats filtration
For most indoor pollutants the highest-leverage intervention is not a device. These are the changes worth making before, or instead of, buying anything.
- Make the bedroom permanently pet-free and keep the door closed. This is the highest-impact change available.
- Run a HEPA purifier in the bedroom continuously — pet allergen is the case where this genuinely works.
- Replace carpets and heavy upholstery with hard floors and washable covers where you can.
- Wash pet bedding weekly in hot water.
- Wash hands and change clothes after extended contact, particularly before going to bed.
Frequently asked questions
Do air purifiers help with pet allergies?
How long does cat allergen stay in a house?
Are there hypoallergenic cats or dogs?
Where should I put an air purifier for pet allergy?
Sources
Every limit and standard quoted on this page comes from one of the documents below. Where a figure is not in one of these, we have not published it.
WHO Guidelines for Indoor Air Quality: Selected Pollutants
World Health Organization · published 2010-01-01 · checked 2026-08-01
Covers formaldehyde, benzene, carbon monoxide, naphthalene, nitrogen dioxide, PAHs, radon, trichloroethylene and tetrachloroethylene specifically as indoor pollutants.
This page states what published standards say and what the physics of each technology allows. It does not state what is in your supply — no page can. Where the two questions meet is a test result, and every entry in this library says which test to ask for.