Air Treatment Filters: Classification, Efficiency and Selection by Industrial Application
Technical reference guide on air filter classification according to ISO 29463 and EN 1822:2009. From G pre-filters to ULPA U17, with efficiencies, penetration values and applications across industrial, pharmaceutical and cleanroom sectors.
Indoor air quality is a critical factor for human health, product integrity and regulatory compliance in industrial and service environments. A poorly specified filtration system does not only compromise health protection: it can unnecessarily increase energy consumption or reduce HVAC equipment service life.
1. Why air filtration matters
Humans breathe approximately 0.7 kg of air per hour. Air contains a mixture of particles — salt, pollen, fibres, spores, bacteria — and gases — N₂, O₃, O₂, CO₂, SO₂ — largely invisible to the naked eye. Although the respiratory system acts as a natural barrier, its effectiveness decreases dramatically as particles become smaller.
99.9% of airborne particles have a diameter below 1 µm. At this size range we find diesel particles, oil smoke, tobacco smoke, asbestos fibres and bacteria. Their control is especially critical in healthcare, food and pharmaceutical environments.
2. The four filter groups: PRE, EPA, HEPA and ULPA
3. Full classification table: EN 1822 / EN 16890 and ISO 29463
Overall efficiency measures filter retention performance across its entire surface. Local efficiency (more stringent) measures the lowest-performing point on the filter. For HEPA and ULPA groups, EN 1822 requires both values to be met simultaneously. Classes G, M and F are characterised under EN 16890 and ISO 16890 (MERV index and ePM).
| Group | EN 1822 / EN 16890 Class | ISO 29463 Class | Main application | Overall value | Local value | ||
|---|---|---|---|---|---|---|---|
| % Eff. | % Pen. | % Eff. | % Pen. | ||||
| PRE | G1 | — | Pre-filters: insects, fibres, dust, sand | n/a | n/a | — | — |
| PRE | G2 | — | Pre-filters: insects, fibres, dust, sand | n/a | n/a | — | — |
| PRE | G3 | — | Pre-filters: insects, fibres, dust, sand | n/a | n/a | — | — |
| PRE | G4 | — | Pre-filters: insects, fibres, dust, sand | n/a | n/a | — | — |
| — | M5 | — | Workshops, factories, warehouses | n/a | n/a | — | — |
| — | M6 | — | Offices, warehouses, pre-filters for E10/E11 | n/a | n/a | — | — |
| — | F7 | — | Data centres, hospitals, pre-filters for H12–H14 | n/a | n/a | — | — |
| — | F8 | — | Data centres, hospitals, pre-filters for H12–H14 | n/a | n/a | — | — |
| — | F9 | — | Data centres, hospitals, pre-filters for H12–H14 | n/a | n/a | — | — |
| EPA | E10 | — | Food processing, pharmaceutical | 85% | 15% | — | — |
| EPA | E11 | ISO 15/20 E | Food processing, pharmaceutical | 95% | 5% | — | — |
| EPA | E12 | ISO 25/30 E | Food processing, cleanrooms | 99.5% | 0.5% | — | — |
| HEPA | H13 | ISO 35/40 H | Nuclear, sterile environments, pharmaceutical | 99.95% | 0.05% | 99.75% | 0.25% |
| HEPA | H14 | ISO 45 H/50 U | Electronics, advanced pharmaceutical | 99.995% | 0.005% | 99.975% | 0.025% |
| ULPA | U15 | ISO 55/60 U | Electronics, pharmaceutical | 99.9995% | 0.0005% | 99.9975% | 0.0025% |
| ULPA | U16 | ISO 55/60 U | Electronics, pharmaceutical | 99.99995% | 0.00005% | 99.99975% | 0.00025% |
| ULPA | U17 | ISO 75 U | Laboratories, high-containment pharmaceutical | 99.999995% | 0.000005% | 99.9999% | 0.0001% |
4. Pressure drop and energy cost: the decisive factor
An air filter generates a pressure drop that the HVAC or AHU fan must overcome. This drop increases with filtration grade and grows progressively as the filter accumulates retained particles.
An H13/H14 filter poorly specified for a system that does not require it can significantly multiply fan energy consumption. In high-airflow installations, optimising the filter cascade with efficient pre-filters can reduce energy costs by 20% to 40%.
- Efficacy vs. energy efficiency: Efficacy measures how many particles are captured. Energy efficiency measures how many are captured per unit of energy consumed. Both must feature in the system specification.
- Initial and final resistance: End-of-life resistance determines replacement frequency. An over-loaded filter increases power consumption and may compromise filter structural integrity.
- Total cost of ownership (TCO): A higher-quality filter with slightly higher initial resistance may deliver lower TCO if its service life is significantly longer.
- Cascade systems: Combining G4/F7 pre-filters with H13/H14 final filters extends HEPA service life and substantially reduces overall replacement cost.
5. Application by industrial sector
- Food and beverage: F7/F8 pre-filters + E10/E11 final filters in production areas. E12 or H13 for aseptic packaging.
- Pharmaceutical and biotech: H13/H14 in GMP Grades A/B cleanrooms; F9+H13 in Grades C/D. U15–U17 for BSL-3/4 and high-sensitivity sterile products.
- Hospitals: F7+H13 for ICU, operating theatres and haematology. F7+H14 for immunocompromised patient isolation rooms.
- Electronics and microelectronics: H14 or U15 in ISO Class 5–7 cleanrooms (ISO 14644-1). U16/U17 for lithography and semiconductor manufacturing.
- Data centres: F7/F8 for most applications. F9 for critical Tier III/IV facilities.
BOIXAC provides advisory services on the selection, specification and integration of air filtration systems in AHUs and industrial HVAC systems. We have experience in pharmaceutical, food, hospital and electronics projects where air quality and energy cost requirements are simultaneously critical. Contact our technical team for a no-commitment assessment.