What's in my air
PM10 — the dust fraction, and why it behaves differently indoors
PM10 is airborne particulate matter with an aerodynamic diameter of 10 micrometres or less, which includes the PM2.5 fraction and adds the coarser dust particles above it.
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 NAAQS — annual average | 60 µg/m³ | — |
| India NAAQS — 24-hour average | 100 µg/m³ | — |
| WHO 2021 guideline — annual | 15 µg/m³ | — |
| WHO 2021 guideline — 24-hour | 45 µg/m³ | — |
Where it comes from
Road dust resuspension
Traffic lifting settled dust back into the air. The single largest PM10 source in most Indian cities and largely absent from PM2.5.
Construction and demolition
Highly localised and often the dominant source for a specific building or street.
Wind-blown soil
Substantial in arid regions and during dust transport events from the west.
Indoor activity
Sweeping, dry dusting, textile fibres and shaking out bedding generate coarse particles directly.
Why it matters
- Coarse particles deposit in the upper airway rather than the deep lung, which is why the health evidence for PM2.5 is stronger and the guideline values are tighter.
- PM10 is a bigger nuisance factor: visible settled dust, irritated eyes and throat, and it is what people mean when they say a room is dusty.
- For anyone with allergic rhinitis or asthma, the coarse fraction carries much of the allergen load — pollen, mould spores and dust mite debris all sit in this size range.
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? | Visible as settled dust on surfaces within a day. Often gritty and noticeable in the throat. |
| What a consumer monitor shows | Most consumer monitors report PM10 alongside PM2.5, but the PM10 figure is generally less reliable — optical sensors under-count large particles because they do not stay in the sensing airstream well. |
| Field test | A settled-dust check is genuinely informative: wipe a dark surface with a white cloth after 24 hours with windows closed, and repeat with them open. |
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.
- Pre-filter (washable mesh or coarse media)Effective
Coarse particles are captured trivially by interception. This is what the pre-filter is for, and it is why cleaning it matters.
- HEPA filtrationEffective
Removes PM10 completely, but using an expensive HEPA to catch dust that a pre-filter would have caught wastes the HEPA's life.
- Wet mopping instead of sweepingEffective
Sweeping resuspends settled coarse dust into breathing air. Wet mopping removes it. Free, and one of the highest-value changes in a dusty Indian home.
- Vacuum with a sealed HEPA systemPartial
Effective if genuinely sealed. A vacuum with a HEPA filter but a leaky body exhausts fine dust back into the room.
Caveat: Look for sealed-system claims, not just a HEPA cartridge.
- Door sweeps and window sealingPartial
Coarse particles infiltrate through gaps and settle. Closing the gaps is disproportionately effective for this fraction.
What does not work
Each of these is commonly assumed — or actively marketed — to help with pm10. None of them do.
Ionisers
Charged coarse particles deposit on surfaces — which for PM10 means visible dust on your walls and furniture rather than clean air.
Dry dusting and sweeping
Actively makes PM10 worse by resuspending settled particles into the breathing zone.
Ozone generators
No particle removal, and they add a regulated pollutant.
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.
- Wet mop rather than sweep. This is the single largest indoor PM10 reduction available in most Indian homes.
- Fit door sweeps on external doors, particularly on the ground floor and street-facing side.
- Keep windows closed on the street-facing side during peak traffic hours if you live on a busy road.
- Clean the purifier's pre-filter every two to four weeks in a dusty area. A clogged pre-filter cuts airflow, which cuts CADR, which cuts everything.
Frequently asked questions
What is the difference between PM10 and PM2.5?
Does an air purifier remove PM10?
Why is PM10 so high in Indian 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.
National Ambient Air Quality Standards (NAAQS), notification dated 18 November 2009
Central Pollution Control Board, Ministry of Environment, Forest and Climate Change · published 2009-11-18 · checked 2026-08-01
India's legally applicable ambient air standards. They are ambient (outdoor) standards — India has no equivalent statutory indoor air quality standard for homes.
World Health Organization · published 2021-09-22 · checked 2026-08-01
The 2021 revision tightened most values substantially. WHO guideline values are health-based targets, not regulatory limits, and are considerably stricter than India's NAAQS.
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.