Short answer
ISO 16890 is the current international standard for air filters used in general ventilation. It replaced EN 779:2012, which was withdrawn across Europe on 30 June 2018. There is no exact one-to-one conversion between the two: an F7 filter is not “equal to” one specific ISO 16890 class, only to a range of possible classes. ISO 16890 classifies a filter by how much of the airborne particulate matter it removes – ePM1, ePM2.5, ePM10 or ISO Coarse – instead of by efficiency at a single 0.4 µm particle size. MERV (ANSI/ASHRAE 52.2) remains a separate North American system and also has no exact equivalence with either.
Key facts at a glance
- Current standard: EN ISO 16890, in four parts – Part 1 (classification) ISO 16890-1:2016, Part 2 (fractional efficiency and air flow resistance) ISO 16890-2:2022, Part 3 (gravimetric efficiency and dust holding capacity) ISO 16890-3:2024, Part 4 (IPA conditioning) ISO 16890-4:2022.
- Withdrawn standard: EN 779:2012 – classes G1–G4, M5–M6, F7–F9. No longer valid for new product classification in CEN member states.
- Above ISO 16890: EPA, HEPA and ULPA filters are not covered by ISO 16890. They are classified by EN 1822 (E10–U17) and ISO 29463 (ISO 15 E – ISO 75 U).
- North America: MERV 1–16 per ANSI/ASHRAE 52.2. MERV 17–20 appear in some literature but are outside the scope of the 52.2 test method.
- Conversion: Only indicative ranges exist. Always ask for the ISO 16890 test report of the specific filter.
Why EN 779 was replaced
EN 779:2012 rated a filter on its average efficiency for particles of one single size – 0.4 µm – measured while the filter was being loaded with synthetic dust. That number said very little about what the filter actually does to the dust people breathe.
ISO 16890 measures fractional efficiency across the whole 0.3–10 µm range and then weights the result against the real particle size distributions of urban and rural outdoor air. The output is the share of PM1, PM2.5 or PM10 that the filter removes – the same particulate matter fractions used by the World Health Organization and by air quality legislation. A specifier can therefore connect a filter class directly to an indoor air quality target.
The main differences
| EN 779:2012 (withdrawn) | EN ISO 16890 | |
|---|---|---|
| Particle size evaluated | 0.4 µm only | 0.3 µm – 10 µm |
| Classes | G1–G4, M5–M6, F7–F9 | ISO Coarse, ISO ePM10, ISO ePM2.5, ISO ePM1 |
| Electrostatic charge | Media sample discharged (minimum efficiency) | Complete filter element conditioned in isopropanol vapour |
| Loading dust | ASHRAE synthetic dust | ISO A2 Fine test dust |
| Test final pressure drop | G classes 250 Pa; M and F classes 450 Pa | ISO Coarse / ePM10 < 50%: 200 Pa; ePMx ≥ 50%: 300 Pa |
| Geographic scope | Europe (CEN) | International (ISO) |
How an ISO 16890 class is assigned
A filter is placed in the highest group whose requirement it meets, and the reported efficiency is rounded down to the nearest 5%.
| Group | Requirement | Reported as |
|---|---|---|
| ISO ePM1 | Initial ePM1 ≥ 50% and discharged ePM1,min ≥ 50% | ISO ePM1 50% … 95% |
| ISO ePM2.5 | Initial ePM2.5 ≥ 50% and discharged ePM2.5,min ≥ 50% | ISO ePM2.5 50% … 95% |
| ISO ePM10 | Initial ePM10 ≥ 50% (no discharged requirement) | ISO ePM10 50% … 95% |
| ISO Coarse | ePM10 < 50% | ISO Coarse 5% … 95% (gravimetric arrestance) |
Worked example. A V-compact filter previously classified F8 under EN 779 is tested under ISO 16890 and measures 73% ePM1, 80% ePM2.5 and 93% ePM10. Because it passes the ePM1 requirement, it is classified in the highest group it qualifies for and the value is rounded down in 5% steps: ISO ePM1 70%.
The “e” stands for efficiency; the subscript is the particulate matter fraction. ISO ePM1 70% means the filter removes 70% of PM1 particles.
EN 779 to ISO 16890: indicative ranges, not equivalents
A single EN 779 class can land in several different ISO 16890 classes depending on the media used. Two filters that both carried an F7 label can test as ISO ePM1 50% and ISO ePM2.5 65% respectively. This is most pronounced with synthetic electret media, whose efficiency drops once the electrostatic charge is neutralised – exactly what the ISO 16890 conditioning step exposes.
The table below gives the range of measured average efficiencies that filters of each former EN 779 class typically produce when retested under ISO 16890. Use it to narrow a shortlist, never as a substitute for the test report.
| EN 779:2012 class | ePM1 | ePM2.5 | ePM10 |
|---|---|---|---|
| M5 | 5% – 35% | 10% – 40% | 40% – 70% |
| M6 | 10% – 40% | 20% – 50% | 60% – 80% |
| F7 | 40% – 65% | 65% – 75% | 80% – 90% |
| F8 | 65% – 90% | 75% – 95% | 90% – 100% |
| F9 | 80% – 90% | 85% – 95% | 90% – 100% |
G1–G4 filters fall into the ISO Coarse group. Their ISO Coarse value is a gravimetric arrestance figure and is not comparable with an ePMx efficiency.
MERV (ANSI/ASHRAE 52.2) compared
MERV is derived from composite average particle size efficiency in three size ranges: E1 = 0.30–1.0 µm, E2 = 1.0–3.0 µm, E3 = 3.0–10.0 µm. The filter receives the highest MERV for which it satisfies every requirement of that MERV.
| MERV | E1 (0.30–1.0 µm) | E2 (1.0–3.0 µm) | E3 (3.0–10.0 µm) | Indicative ISO 16890 group |
|---|---|---|---|---|
| 1–4 | – | – | < 20% | ISO Coarse |
| 5 | – | – | ≥ 20% | ISO Coarse |
| 6 | – | – | ≥ 35% | ISO Coarse |
| 7 | – | – | ≥ 50% | ISO Coarse – ISO ePM10 |
| 8 | – | ≥ 20% | ≥ 70% | ISO ePM10 |
| 9 | – | ≥ 35% | ≥ 75% | ISO ePM10 |
| 10 | – | ≥ 50% | ≥ 80% | ISO ePM10 – ISO ePM2.5 |
| 11 | ≥ 20% | ≥ 65% | ≥ 85% | ISO ePM2.5 |
| 12 | ≥ 35% | ≥ 80% | ≥ 90% | ISO ePM2.5 |
| 13 | ≥ 50% | ≥ 85% | ≥ 90% | ISO ePM1 |
| 14 | ≥ 75% | ≥ 90% | ≥ 95% | ISO ePM1 |
| 15 | ≥ 85% | ≥ 90% | ≥ 95% | ISO ePM1 |
| 16 | ≥ 95% | ≥ 95% | ≥ 95% | ISO ePM1 |
The last column is a rough orientation only. MERV uses a different aerosol, different size bands and no isopropanol conditioning, so a MERV 13 filter and an ISO ePM1 50% filter are not interchangeable by definition.
Where ISO 16890 stops: EPA, HEPA and ULPA
ISO 16890 covers filters up to roughly ISO ePM1 95%. Above that, filters are tested particle by particle at the Most Penetrating Particle Size (MPPS) under EN 1822 or ISO 29463, and every element is leak tested individually.
| EN 1822 class | Overall efficiency at MPPS | Local efficiency | ISO 29463 class | Group |
|---|---|---|---|---|
| E10 | ≥ 85% | – | no equivalent | EPA |
| E11 | ≥ 95% | – | ISO 15 E | EPA |
| E12 | ≥ 99.5% | – | ISO 25 E | EPA |
| H13 | ≥ 99.95% | ≥ 99.75% | ISO 35 H | HEPA |
| H14 | ≥ 99.995% | ≥ 99.975% | ISO 45 H | HEPA |
| U15 | ≥ 99.9995% | ≥ 99.9975% | ISO 55 U | ULPA |
| U16 | ≥ 99.99995% | ≥ 99.99975% | ISO 65 U | ULPA |
| U17 | ≥ 99.999995% | ≥ 99.9999% | ISO 75 U | ULPA |
ISO 29463 starts at ISO 15 E, so EN 1822 class E10 has no ISO 29463 counterpart. The nearest equivalent under ISO 16890 is ISO ePM1 > 95%.
Choosing a class for a project
Start from the outdoor air quality at the site and the indoor air quality you need to deliver, not from the old filter’s label.
- Pre-filtration and equipment protection: ISO Coarse or ISO ePM10. Protects coils, fans and downstream filters from lint, insects and sand.
- General commercial ventilation: ISO ePM1 50–60% is the usual replacement for what used to be specified as F7.
- Offices and schools in polluted urban air: ISO ePM1 70–80%.
- Hospitals, pharmaceutical and food production: ISO ePM1 80% or higher as the final stage before a HEPA filter.
- Cleanrooms and containment: H13, H14 or higher to EN 1822 / ISO 29463, selected together with the cleanroom class to ISO 14644-1.
Eurovent recommendation REC 4/23 gives filter class guidance based on the outdoor air quality at the installation site and the target indoor air quality. It is the reference most European specifications now follow.
Frequently asked questions
Is EN 779 still valid?
No. EN 779:2012 was withdrawn on 30 June 2018 and replaced by EN ISO 16890. Filters may still be described informally as “F7” or “M5” in the market, but a new filter should be specified, tested and documented to ISO 16890.
What is the ISO 16890 equivalent of an F7 filter?
There is no single equivalent. Filters that were classified F7 typically test between ePM1 40–65%, ePM2.5 65–75% and ePM10 80–90%. In practice ISO ePM1 50–60% is the most common replacement, but the correct answer for a given filter can only come from its test report.
What does ISO ePM1 70% mean?
It means the filter removes 70% of particulate matter with an aerodynamic diameter up to 1 µm, measured across the 0.3–10 µm range and weighted against a standard urban air particle distribution. Reported values are rounded down in 5% steps.
Why does ISO 16890 discharge the filter with isopropanol?
Many synthetic media use an electrostatic charge to capture particles. That charge dissipates in service, so the initial efficiency overstates real performance. ISO 16890-4 conditions the complete element in saturated isopropanol vapour and the test is repeated, so the class reflects efficiency that does not depend on charge.
Is MERV 13 the same as ISO ePM1 50%?
They are broadly comparable in application but not equivalent by definition. The two standards use different test aerosols, different particle size bands and different conditioning. A filter should carry the classification of the standard named in the specification, not a converted value.
Does ISO 16890 cover HEPA filters?
No. ISO 16890 stops at approximately ISO ePM1 95%. EPA, HEPA and ULPA filters are classified by EN 1822 or ISO 29463, which test at the Most Penetrating Particle Size and require an individual leak test on every element.
Which parts of ISO 16890 are current?
ISO 16890-1:2016 for the classification system, ISO 16890-2:2022 for fractional efficiency and air flow resistance, ISO 16890-3:2024 for gravimetric efficiency and dust holding capacity, and ISO 16890-4:2022 for the isopropanol conditioning method.
How do I check a supplier’s ISO 16890 claim?
Ask for the test report of that exact filter model and size. It should state the initial and discharged ePMx efficiencies, the initial pressure drop at nominal airflow, the test final pressure drop and the laboratory that performed the test.
Testing at Ulpatek
Ulpatek tests its filters in its own laboratory, ULPALAB, which is equipped with an ISO 16890 test system, an EN 1822 / ISO 29463 HEPA and ULPA scanning test system, a performance test system and a filter media test system. Ulpatek holds Eurovent certification and produces to ISO 16890 and ISO 29463 (EN 1822).
If you need the test report for a specific filter class, dimension or airflow, contact us at info@ulpatek.com.
