Understanding ISO 16890
An introduction to ePM1, ePM2.5, and ePM10 classification for general ventilation filters.
Why ISO 16890 replaced the older EN 779 classification
ISO 16890 classifies general ventilation filters by efficiency against three particle-size fractions — PM1, PM2.5, and PM10 — rather than the single "average efficiency" figure used by the older EN 779 standard. This gives a more complete picture of how a filter performs across the particle sizes that actually matter for indoor air quality.
The four ISO 16890 groups
Filters are grouped as ISO Coarse, ePM10, ePM2.5, or ePM1, based on which particle-size fraction they can be meaningfully rated against — a filter only earns a PM1 or PM2.5 rating if it captures a minimum percentage of that specific fraction, so the group itself tells you what the filter is actually good at, not just a single blended number.
What this means for cross-referencing older specifications
A building specified under EN 779 (or MERV) needs a considered cross-reference rather than a direct substitution — the classification systems measure different things, so an "equivalent" class under one standard is an approximation, not an exact match, under another.
EEC can review a filter's ISO 16890 classification against a stated indoor air quality target; this guide does not state that a specific EEC product is certified to ISO 16890 without separately confirmed test data.
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