Routine Autopsy

Air Purifier for Smog: Worth Buying? HEPA vs Ioniser vs Nothing (Video)

2:29 min

Read the full written guide: Air Purifier for Smog: Worth Buying? HEPA vs Ioniser vs Nothing →

Learn how a genuine HEPA air purifier can actually lower indoor smog when you pick the right size and keep the room sealed. We break down the basics of true HEPA filters, how to match CADR to your space, and why ionisers and ozone generators should be avoided.

We also share practical running tips, cost considerations, and a clear warning about when to seek medical help. This isn’t medical advice, just everyday guidance for cleaner indoor air.

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Transcript

Can a HEPA filter cut indoor smog by 99.97%?

Can a HEPA filter cut indoor smog by 99.97%?

HEPA Purifier for Smog

Today we'll walk through picking a real HEPA purifier that actually lowers indoor smog, and reveal the single key you need to make it work.

How true HEPA works

A true HEPA filter is a dense mat of ultra-fine glass fibers folded like an accordion. A fan pushes air through, and particles get caught as they collide or stick. Most good units also add a thin carbon layer to mop up odors.

Sizing your purifier

First measure your room: length times width times ceiling height gives you the volume in cubic metres. Multiply that number by five, you want the purifier to exchange the air about five times each hour. Then pick a unit whose CADR meets or exceeds that figure; a larger model on a low setting works fine too.

HEPA capture rate

True HEPA filters capture at least 99.97 percent of particles at the most difficult size, 0.3 microns, which covers the bulk of smog’s PM2.5.

HEPA purifier

If you choose a genuine HEPA unit with the right CADR, it’s definitely worth it, it traps fine particles effectively and can lower indoor PM2.5 during heavy smog.

Ioniser / ozone unit

Units that rely on ionisation or ozone generation should be skipped. Ozone can irritate the lungs, and the promised particle removal is minimal compared to a true HEPA filter.

Running tips

Close doors and windows while the purifier runs, otherwise fresh outdoor air will undo its work. Place the machine on the floor or a low table, at least a hand’s breadth away from walls and curtains, and let it run for half an hour before you go to sleep, then keep it on through the night.

The one key to success

The one thing that guarantees success is pairing a true HEPA purifier with a CADR that can refresh your room’s air at least five times per hour, and keeping the space sealed while it runs.

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Read the full guide

The full guide is on thecareonline.com. General information only, so check with your doctor for your own case.

Nothing on The Care Online is medical advice. Traditional practices are described as tradition, not as fact. Take a persistent or serious concern to a qualified professional. See how videos and posts are made on our methodology page.