What's in my air
Pollen — large, seasonal, and easily filtered
Pollen grains are plant reproductive particles, typically 10 to 100 micrometres across, and among the easiest airborne allergens to filter because of their size.
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 limit | Pollen is not a regulated pollutant. Aerobiological monitoring networks publish counts in some Indian cities but coverage is limited. |
Where it comes from
Grasses
A major allergen source across India, with peaks varying by region and rainfall.
Parthenium (congress grass)
An invasive weed widespread across India and a well-documented cause of allergic rhinitis and contact dermatitis.
Trees
Neem, eucalyptus, Prosopis and others produce substantial pollen loads, generally in the drier months.
Amaranthus and Chenopodium
Common weed pollens identified in Indian aerobiological surveys.
Indoor transport
Pollen enters mainly on clothes, hair, shoes and pets rather than through the air — which is why entry habits matter.
Why it matters
- Allergic rhinitis is common in urban India, and pollen is one of its principal outdoor triggers.
- Sleep quality is where the burden concentrates: overnight nasal congestion has knock-on effects that people rarely attribute to air quality.
- It is a genuinely tractable problem indoors, because pollen is large and filtration works well against it — unlike most pollutants in this library where the answer is more equivocal.
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 — sneezing, itchy eyes, nasal congestion following a seasonal pattern. Visible yellow dust in high-pollen periods. |
| What a consumer monitor shows | PM10 sensors register pollen as part of the coarse fraction, but no consumer monitor identifies pollen specifically. A rising PM10-minus-PM2.5 gap during a known season is suggestive and no more. |
| Field test | Symptom diaries against local pollen calendars are more useful than any device. Allergy testing through a clinician identifies the specific trigger, which is what actually changes behaviour. |
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 filtrationEffective
Effectively complete for intact grains
Pollen is far larger than the most penetrating particle size, so capture is essentially total. This is the easiest job a HEPA filter does.
- Pre-filterEffective
Even a washable mesh pre-filter captures most intact pollen. You do not need a premium unit for this specific problem.
- Keeping bedroom windows closed during peak seasonEffective
Pollen concentrations are usually highest in the morning. Ventilating at other times reduces what enters.
- Changing clothes and showering after coming homeEffective
Most indoor pollen arrives on people rather than through the air. This is free and effective, and it is what allergy clinicians advise first.
- Washing bedding weekly in hot waterPartial
Removes accumulated pollen and dust mite allergen from the surface you spend eight hours against.
What does not work
Each of these is commonly assumed — or actively marketed — to help with pollen. None of them do.
Ionisers
Deposit pollen on surfaces where it can be resuspended, rather than removing it from the room.
Ozone generators
Do not destroy allergen proteins at safe concentrations, and add a pollutant.
Running a purifier only during symptoms
Not a technology failure but a timing one — allergen load accumulates, so continuous operation during the season works better than reactive use.
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.
- Close bedroom windows during morning peak-pollen hours in your local season.
- Change clothes and rinse hair after coming home during high season — most indoor pollen arrives on people.
- Wash bedding weekly in hot water.
- Keep pets out of the bedroom during pollen season; fur carries pollen indoors efficiently.
- Get tested for the specific allergen. Knowing whether it is grass, parthenium or a tree pollen changes which weeks matter.
Frequently asked questions
Does a HEPA filter remove pollen?
Where should I put an air purifier for pollen allergy?
Why do my symptoms persist after the pollen season?
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.