What Is the Difference Between HEPA and ULPA Filters?

Filtration accuracy and efficiency: A HEPA filter provides filtration efficiency of at least 99.97% for 0.3 μm particles at the H13 level. ULPA filters target even smaller particles—down to 0.12 μm—and can achieve efficiency above 99.9995% at the U15 level, enabling them to capture finer contaminants such as viruses and nanoscale dust.

Classification standards: Under European EN standards, HEPA filters are classified from H10 to H14, while ULPA filters are classified from U15 to U17. Under the U.S. IEST-RP-CC001 standard, a ULPA filter must achieve efficiency of at least 99.999% for 0.12 μm particles, whereas a HEPA filter must achieve efficiency of at least 99.97% for 0.3 μm particles.

Applications: HEPA filters are widely used in hospital operating rooms, premium household air purifiers, and Class 10,000 cleanrooms. ULPA filters are used in environments with exceptionally stringent particle-control requirements, such as semiconductor manufacturing at process nodes below 14 nm, Biosafety Level 4 laboratories, and Class 10 cleanrooms.

Cost and airflow resistance: ULPA filter media require more complex manufacturing processes, such as layered ultrafine glass fibers. As a result, ULPA filters cost three to five times as much as HEPA filters and create greater airflow resistance, requiring fan systems with higher static pressure. They are therefore generally reserved for applications where ultra-clean conditions are essential.

In simple terms, HEPA is the standard for high-precision purification, while ULPA represents the highest level of cleanliness. The right choice depends on the application's particle-control requirements and budget. HEPA filtration is generally sufficient for conventional medical and household use, while ULPA is appropriate for semiconductor manufacturing, biosafety facilities, and other applications with virtually zero tolerance for airborne particles.