EN 779 was a European standard used for classifying and testing air filters primarily used in general ventilation systems. Before its replacement by the ISO 16890 standard in 2016, EN 779 was the main reference in Europe for determining the efficiency of air filters. Here's a more detailed explanation of what EN 779 involved:

The primary goal of EN 779 was to provide a uniform basis for the classification of air filter performance, ensuring comparability and reliability across different products and manufacturers within the European market.

Testing Procedures

The standard prescribed specific methods for testing air filters, including:

  • Test Dust: The filters were tested using a synthetic test dust to simulate real-world conditions.
  • Dust Holding Capacity: This was measured to determine how much dust a filter could hold before its efficiency decreased.
  • Particle Size: EN 779 focused primarily on particles around 0.4 micrometers. Filters were assessed based on their ability to capture these particles.

Efficiency Classification

Filters were classified based on their average arrestance (for coarse filters) and their average efficiency (for fine filters):

  • G1-G4: These were coarse filters, with G4 being the most efficient among them. They were typically used for larger particles such as pollen, hair, and dust.
  • M5-M6: Medium efficiency filters, capable of capturing smaller particles including mold spores and cement dust.
  • F7-F9: Fine filters, designed to remove very small particles such as smoke, bacteria, and aerosol particles.

Filter Grades

Each filter grade corresponded to a specific efficiency range, enabling users to select a filter based on the specific needs of their environment or application. For example, higher-grade filters (F7-F9) were often used in settings requiring higher air quality, such as hospitals and laboratories.


The classification provided by EN 779 helped in choosing the right filter for various applications, whether for simple residential use or more critical applications like healthcare facilities.

Limitations and Transition to ISO 16890

Although EN 779 provided a useful framework for filter testing, it was limited by its focus on a relatively narrow particle size range. The subsequent ISO 16890 standard introduced a more comprehensive classification system based on a wider range of particle sizes (from 0.3 to 10 micrometers), aligning more closely with global practices and providing a better reflection of a filter's performance in various conditions.

EN 779 was significant for standardizing air filter ratings in Europe, but the adoption of ISO 16890 has provided a more nuanced and globally applicable approach to classifying air filter efficiency