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What Is a HEPA Filter And Does the Grade Actually Matter?
If you've ever shopped for an air purifier, you've seen the term "HEPA filter" everywhere. But what does it actually mean, and does the grade matter?
What Does HEPA Stand For?
HEPA stands for High Efficiency Particulate Air. It's a filtration standard that defines how effectively a filter captures airborne particles. To qualify as HEPA, a filter must trap at least 99.97% of particles at 0.3 microns in diameter, the size that's hardest to capture because it's too large for diffusion but too small for interception.
What Does a HEPA Filter Capture?
A certified HEPA filter captures:
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Dust and dust mites
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Pollen and mould spores
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Pet dander
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Bacteria and some viruses
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Fine particulate matter (PM2.5)
In short, the things you can't see but breathe in every day.
What's the Difference Between HEPA Grades?
Not all HEPA filters are equal. Filters are graded by how much they capture:
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H10: captures 85% of particles
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H11: captures 95% of particles
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H12: captures 99.5% of particles
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H13: captures 99.97% of particles → True HEPA
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H14: captures 99.995% of particles
H13 is the standard most commonly referred to as "True HEPA," and it's what you'll find in higher-quality air purifiers like the PRISM+ Aura and Vortex series. The difference between H10 and H13 is significant, an H10 filter lets through 15 times more particles than an H13.
Why Does This Matter in Singapore?
Singapore's climate comes with high humidity, urban haze, and year-round heat, which means indoor air quality can be a real concern. HEPA H13 filtration is particularly relevant if you have children, elderly family members, or anyone with asthma or respiratory sensitivities at home.
Is a HEPA Filter Enough on Its Own?
HEPA filters are excellent for particles, but they don't capture gases or odours. That's why most quality air purifiers pair a HEPA filter with an activated carbon filter. HEPA handles the particles, carbon handles the gases, smells, and formaldehyde.
PRISM+ air purifiers use a 3-layer defence: a pre-filter for larger particles, a medical-grade HEPA H13 filter, and activated carbon to neutralise airborne pollutants and absorb formaldehyde.
How Often Does a HEPA Filter Need Replacing?
Typically every 6 to 12 months, depending on usage and air quality. Running your purifier in a dusty or high-pollution environment will clog the filter faster. Most air purifiers have an indicator light that tells you when it's time.
PRISM+ makes this easier with our prepaid filter subscription where you can choose how frequently a fresh filter is delivered to your door.
The Bottom Line
If you're buying an air purifier, look for H13 or True HEPA certification, and for an activated carbon filter.