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Air Quality at Home

HEPA Filters: What They Do and How to Choose One

By The Breathizen Team · Published · Reviewed September 22, 2026

A purifier is one of the few wellness purchases with straightforward physics behind it: air goes through a dense filter, and particles stay behind.

Quick answer: A true HEPA filter captures at least 99.97 percent of particles 0.3 microns in size, including dust, pollen, pet dander and smoke. Match the purifier's clean air delivery rate to your room size.

The bigger picture

Air quality is the part of respiratory wellness you can engineer. You cannot change your age or your genes, but you can change what you breathe at home and at work. Attention to HEPA air purifiers pays off every hour of every day, quietly, which is more than can be said for almost any product.

How HEPA works

The filter is a mat of fine fibres. Large particles hit fibres directly, mid-sized ones are intercepted and the smallest wander into fibres through random motion. The hardest size to catch is around 0.3 microns, which is why it sets the standard.

Sizing it correctly

Look for CADR, the clean air delivery rate. A common rule is a smoke CADR at least two-thirds of the room's area in square feet. An undersized unit running on low does very little.

What HEPA does not do

It does not remove gases, odours or VOCs; that needs activated carbon. Avoid units that generate ozone. Filters clog, so budget for replacements every six to twelve months.

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Practical tips you can use today

  • Run it in the bedroom, where you spend the most hours.
  • Keep doors and windows closed while it runs.
  • Replace filters on schedule.
  • Skip ionizers and ozone generators.

Common mistakes to avoid

  • Masking odours with fragrance instead of ventilating.
  • Forgetting filter changes until airflow drops.
  • Assuming indoor air is clean because it looks clean.
  • Buying a purifier too small for the room.

Where Breathizen fits

We would rather be useful than persuasive, so let us be precise. Nothing in a bottle changes the fundamentals of HEPA air purifiers. What Breathizen offers is a pleasant, ten-second daily ritual built on herbs with a long traditional history for the chest and throat. Customers who like it usually describe gradual, modest benefits. Customers who do not are refunded within 60 days.

What you would see if you turned our bottle around: directions to shake well and take the serving by mouth; a caution for pregnant or nursing women and anyone under 18; a note to consult a physician if you have a medical condition; and a 154 mg blend of mullein, ginger and lemon. Dietary supplements are not FDA approved, and ours makes no such claim. You can read more about how Breathizen works and Breathizen benefits on the Breathizen site.

When to see a doctor

Cleaner air helps everyone, but symptoms still need proper assessment. If you have a cough, wheeze or chest tightness that persists after improving your home's air, or symptoms that ease on holiday and return at home or work, tell your doctor about that pattern. Sudden breathlessness, chest pain or coughing blood need urgent care.

Key takeaways on HEPA air purifiers

  • A true HEPA filter captures at least 99.97 percent of particles 0.3 microns in size, including dust, pollen, pet dander and smoke.
  • How HEPA works: the basics matter most.
  • What HEPA does not do is where small daily actions pay off.
  • Supplements such as Breathizen are optional extras, never substitutes for medical care.

Covered for 60 days

Try Breathizen alongside the habits above. Not for you? Send it back. Full terms on the Breathizen official website.

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Frequently asked questions

Do air purifiers really work?

True HEPA purifiers sized for the room reduce airborne particles substantially. They do not remove gases without a carbon filter.

Are scented candles bad for indoor air?

They add fine particles and volatile compounds. Occasional use with ventilation is a small exposure; daily use in closed rooms adds up.

Is Breathizen inhaled?

No. It is a liquid taken by mouth and swallowed. It is not an inhaler or a medicine.

Sources

How we prepared this article: our team drafted it from public health sources, linked below, and checked every Breathizen fact against the printed label. It is general information, not medical advice.

Written by The Breathizen Team. We make Breathizen, so we write about it in our own voice and check every product fact against the printed bottle label before publishing. Health statements are linked to public sources such as the NIH and the American Lung Association. Read our editorial standards. Last reviewed September 22, 2026.

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