Air purifier buying checklist
Open a section, slide each feature to what you want, and print your own air purifier wish list at the end.
CADR (clean air delivery rate) is how much filtered air the purifier pushes out per hour. Match it to your room, and pick one size up so it can run quietly at medium speed.
A bedroom of about 150 to 200 sq ft
Rough, for about five air changes an hour with a 10 ft ceiling. Ignore "covers X sq ft" claims without a CADR figure.
Keeps a regular bedroom clean, even on bad AQI days.
How many times an hour the purifier can pass all the room's air through its filter. Divide CADR by the room's volume to work it out.
All the room's air passes through about every 15 minutes
A simple way to picture it. Each pass removes most, not all, of the dust in the air.
A good target for daily use in Indian cities.
HEPA is a tested standard for fine dust filters. It is what traps PM 2.5, the tiny smog particles that reach deep into the lungs.
Traps at least 99.95% of the hardest-to-catch particles. The right choice for most homes.
HEPA catches particles but not smells or gases. A carbon layer soaks up cooking smells, incense, smoke and paint fumes.
A thin coated layer. Helps a little and fills up quickly.
A coarse outer mesh that catches hair, lint and big dust first, so the costly HEPA filter lasts longer.
Rinse it every couple of weeks in dusty months to keep the main filter fresh.
Some purifiers use ionisers that give off ozone, a gas that irritates the lungs. A purifier should never add pollution to your room.
No ozone-producing parts. Look for an "ozone-free" claim or a tested emission figure.
Extra features that claim to kill germs. A HEPA filter already traps them, and air moves past a UV lamp too fast for it to do much.
HEPA and carbon do the real work. Nothing extra to replace or worry about.
PM 2.5 are fine particles from smoke, traffic and dust, the main pollutant in Indian winter smog. A sensor shows how clean your room really is.
Shows the actual PM 2.5 level, so you can see the purifier working.
Uses the sensor to speed up when air gets worse, like when someone cooks or opens a window, and slow down when it is clean.
Adjusts itself, saving power and noise when the air is clean.
An app lets you check the air and switch the purifier on before you get home. Handy, but not needed for clean air.
Nothing to set up. Works the same for years.
Locks the buttons so small children cannot change settings or switch the purifier off.
Fine if there are no small children at home.
Noise is measured in decibels (dB). A sleep mode drops the fan to a whisper and dims the lights, so you can run it all night.
Runs all night for most sleepers
Rough idea of how much of the night you can run it without noticing.
Low fan and dim lights. Around 30 dB or less is like a whisper.
Purifiers run for hours every day in winter, so the motor matters. Most use about as much as a ceiling fan or less.
A brushless DC motor uses less power and runs quieter at low speeds.
Whether it is easy to carry between the bedroom at night and the living room by day.
Best if each room gets its own purifier.
How long the main filter is rated to last. Ratings assume moderate pollution, so in smoggy winters filters often wear out sooner.
Usually about one filter a year
Rough, for daily use in a north Indian city. Filters wear out sooner when AQI stays very poor.
Usually one filter a year in normal use.
A purifier is only as good as its next filter. Check that genuine filters are easy to buy, because look-alike ones may not be real HEPA.
Genuine filters from the brand, stores and authorised sellers.
A light or alert that tells you when the filter needs replacing, so you do not keep running a clogged one.
Counts running hours. Good enough for most people.
Your wish list
AIR PURIFIER WISH LIST
by TechPP Insights
Your next air purifier should have these minimum features
Your picks will print here.
Scan to make your own wish list
techpp.app
Choose at least one spec to print your wish list.
Sorting out the rest of the home? Water purifier checklist or air conditioner checklist
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