Each year from late in the year to early the next, when air stagnates and open burning occurs in many areas, fine particulate matter of 2.5 microns or less in Bangkok, its surroundings and the North periodically exceeds standards. Particles this small reach deep into the lungs and bloodstream, affecting health — especially children, the elderly and people with respiratory conditions. We spend most of our time at home, so cleaner indoor air is the most effective protection, and it's best prepared before the season arrives.
Follow air-quality readings from official sources such as the Pollution Control Department's app and website, which show data from monitoring stations near you. Use them to decide when to keep the house closed and when to ventilate. Inexpensive home particle monitors help show whether your purifier is working; less accurate than reference instruments, they're good for trends.
| Issue | What to look for |
|---|---|
| Filter type | High-efficiency filters that capture fine particles well |
| Clean-air delivery rate | Matched to room size; small units in big rooms help little |
| Placement | In the room you use most, such as the bedroom, with space from walls for airflow |
| Use | Doors and windows closed; run continuously on high-dust days |
| Maintenance | Replace filters on schedule; saturated filters lose much of their effect |
| Avoid | Units relying mainly on ozone generation, which can irritate airways |
In multi-room homes, a purifier in each bedroom usually beats one large unit in the living room, since sleep is when we spend longest in one room.
Many detached houses and townhomes leak around door and window frames, through vents above doors, eave vents and service penetrations, letting dust in continuously. Rubber seals on doors and windows, sealant along joints and closing unnecessary vents make purifiers effective. Condos are usually tighter than low-rise homes, but check balcony door edges and bathroom vents.
Keeping a home sealed all the time raises carbon dioxide and humidity, making rooms stuffy and drowsy. Ventilate when dust levels are low, or install a filtered fresh-air system that draws outside air through filters before it enters — well suited to renovations or new builds. Most air-conditioners recirculate indoor air without drawing outside air; cleaning their filters regularly reduces dust build-up but doesn't replace a purifier.
Houseplants make homes pleasant but can't reduce PM2.5 to a health-relevant degree. Spraying water or mist indoors doesn't meaningfully reduce fine dust and can raise humidity enough for mould. Ordinary cloth masks filter fine dust poorly; on high-dust days outside, use masks designed for fine particles, fitted snugly to the face.
Check the clean-air delivery rate and the manufacturer's recommended room size, choosing a unit rated slightly above your room so it cleans quickly at a setting quiet enough for sleep.
Dust depends mainly on citywide weather, but units away from main roads and construction sites get less from nearby sources, and well-sealed units make indoor air easier to control.
In dust season, continuous running in occupied rooms keeps levels low. On clean-air days you can reduce or switch off and open windows instead.
Managing PM2.5 at home starts with monitoring air quality, choosing a room-appropriate purifier and maintaining filters, sealing gaps, ventilating sensibly and reducing indoor sources. Prepare now before the season arrives. Read about cooler home design and family homes on the MyProperty blog.
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