What's in my air
Dust mite allergen — a bedding problem, not an air problem
House dust mites are microscopic arachnids living in bedding, upholstery and carpets, whose faecal particles carry the allergen responsible for a large share of perennial allergic rhinitis and asthma.
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 | — |
| Clinical practice | Relative humidity below 50% cited as suppressing mite populations | A widely used practical target in allergy management rather than a regulatory limit. |
Where it comes from
Mattresses and pillows
The primary reservoir. Warm, humid and richly supplied with shed skin — ideal mite habitat, and where you spend eight hours a night.
Upholstered furniture and carpets
Secondary reservoirs, significant in homes with fitted carpet — less common in India than in temperate countries, which is one reason mite burden differs.
Soft toys and heavy curtains
Frequently overlooked reservoirs, particularly in children's bedrooms.
Humid coastal climates
Mumbai, Chennai, Kochi and Kolkata sustain higher mite populations year-round than dry inland cities.
Why it matters
- Dust mite allergen is one of the most common perennial triggers for allergic rhinitis and asthma, and unlike pollen it does not have an off-season.
- Exposure is concentrated in bed, over eight continuous hours, at close range.
- It is also one of the areas where households spend money on the wrong intervention most consistently — buying a purifier when encasements and humidity control would do more for a tenth of the cost.
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: morning nasal congestion and sneezing on waking, symptoms that improve when away from home, and worsen on making the bed. |
| What a consumer monitor shows | No consumer monitor detects dust mite allergen. A hygrometer showing sustained humidity above 60% is the useful proxy, and it costs a few hundred rupees. |
| Field test | Semi-quantitative allergen test kits for settled dust exist. Clinical allergy testing is more useful, because it establishes whether mites are actually your trigger. |
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.
- Allergen-proof mattress and pillow encasementsEffective
A tightly woven barrier between you and the reservoir. The most effective single intervention and among the cheapest.
- Humidity control below 50% RHEffective
Mites cannot drink; they absorb moisture from air. Sustained lower humidity suppresses populations at the source.
Caveat: Genuinely difficult in coastal Indian cities during monsoon without a dehumidifier or air conditioning.
- Weekly hot washing of bedding (60 °C+)Effective
Kills mites and removes accumulated allergen. Cold washing removes some allergen but does not kill mites.
- Removing carpets and heavy soft furnishing from bedroomsPartial
Reduces the reservoir. Hard floors that can be wet-mopped are substantially better.
- HEPA air purifierMinimal
Captures the fraction that is briefly airborne after disturbance — bed-making, vacuuming, sitting down heavily on a sofa.
Caveat: Genuinely secondary. Buy the encasements first; if you have already bought the purifier, buy the encasements anyway.
- Sealed-system HEPA vacuumPartial
Removes allergen from reservoirs. A vacuum without a sealed body exhausts fine allergen back into the room and makes matters worse.
What does not work
Each of these is commonly assumed — or actively marketed — to help with dust mite allergen. None of them do.
Air purifier as the primary intervention
The allergen particles are large and settle within minutes. Most of the allergen you are exposed to is in your mattress, not in the air, and a purifier does nothing to it.
Ionisers
Deposit allergen on surfaces where it is resuspended by movement.
Ozone generators
Do not denature allergen proteins at safe concentrations, and add a pollutant.
Sunning mattresses
A traditional practice with limited effect. Indian humidity means mattresses reabsorb moisture quickly, and the temperature reached is generally insufficient.
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.
- Buy allergen-proof encasements for mattress and pillows. This is the highest-value intervention and it costs less than a purifier filter.
- Wash bedding weekly at 60 °C or above.
- Keep bedroom relative humidity below 50% where climate allows — air conditioning helps, a hygrometer tells you whether it is working.
- Remove carpets, heavy curtains and stored soft toys from bedrooms.
- Vacuum with a sealed HEPA machine, and leave the room for twenty minutes afterwards while disturbed allergen settles.
Frequently asked questions
Do air purifiers help with dust mite allergy?
What kills dust mites?
Why are my dust allergy symptoms worse in the morning?
Are dust mites worse in coastal cities?
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.