EN 779 vs ISO 16890: What Changed and Why It Matters for Filter Selection

If you still see EN 779 ratings on drawings, product sheets or spare filter labels, you are not alone. Many sites in Australia are working with a mix of old and new filter classifications, and that can make replacement decisions confusing. The key is understanding what changed, what the current ISO 16890 classes mean, and how to compare legacy ratings without assuming a direct conversion.

Why the industry moved from EN 779 to ISO 16890

EN 779 was widely used to classify general ventilation filters, using groups such as G3, G4 and F5 to F9. Those labels were familiar to facility managers and contractors, but they did not always describe real-world performance in a way that reflected the particles filters actually face in modern buildings.

ISO 16890 was introduced to make filter selection more relevant to particle sizes found in outdoor and indoor air. Instead of relying only on a single test dust and a broad class name, ISO 16890 classifies filters by how well they capture particles in different size bands linked to PM10, PM2.5 and PM1.

In practical terms, that means the newer system gives buyers a clearer picture of what a filter is likely to do in service, rather than just how it performed in a legacy laboratory test.

What changed in the rating approach

The biggest change is that ISO 16890 focuses on particle size distribution and efficiency across several ranges, rather than a simple class label that bundles performance into one letter-and-number code.

Under ISO 16890, you will usually see labels such as:

• •ePM10
• •ePM2.5
• •ePM1
• •Coarse

These classes are tied to the proportion of particles captured in those size ranges, which is more useful when choosing filters for offices, workshops, hospitals, schools, warehouses or process areas with different air quality needs.

That does not mean the older EN 779 ratings were useless. It means they are now superseded by a system that is better aligned with how air filters are assessed and selected today.

How to compare EN 779 ratings with ISO 16890 classes

This is where many buyers get caught out. EN 779, MERV, and ISO 16890 do not convert directly, and there is no safe one-size-fits-all conversion table to rely on for specification work.

A practical comparison usually starts with understanding the role of the existing filter stage:

• •G3/G4 legacy filters were often used as pre-filters or general coarse filtration in supply air systems.
• •F5-F7 were commonly selected where finer filtration was needed upstream of final filters or in more demanding commercial systems.
• •F8-F9 were used where higher fine-particle capture was required, often as a final filter stage in general ventilation.

Under ISO 16890, those older choices may map to different ePM classes depending on the product design and test results. That is why the safest approach is to compare the actual published performance data for the specific filter, not just the old class name.

If you are replacing a legacy product, check:

• •the existing filter size and frame style
• •the system airflow and available resistance
• •whether the filter is acting as a pre-filter, medium filter or final stage
• •the old EN 779 class and the new ISO 16890 class on the product sheet
• •the filter manufacturer’s recommended application

If you need help measuring a replacement, our guide on how to measure an air filter is a useful starting point.

What buyers should look for on current product data sheets

When comparing filters, do not stop at the class label. A useful data sheet should tell you how the filter is intended to perform in the system, not just how it is named.

Look for information such as:

• •ISO 16890 classification, including the ePM rating where relevant
• •initial resistance or pressure drop
• •filter dimensions and frame type
• •media type and construction
• •operating limits stated by the manufacturer
• •whether the filter is intended for coarse, medium or fine filtration

For some systems, a multi-stage approach is the best fit, with a coarse pre-filter protecting a finer final filter. In other applications, a single carefully selected filter may be enough. The right answer depends on the equipment, the contamination level and the maintenance approach used on site.

If you are reviewing an existing system, filter servicing can also help you assess whether the current filter arrangement still suits the equipment and operating conditions.

Why the change matters for maintenance and procurement

The move to ISO 16890 matters because it affects how you specify replacements, compare brands and explain requirements to technicians or contractors.

Better alignment with the real job of the filter

A filter is selected to capture particles at a certain point in an air handling system. ISO 16890 gives a clearer picture of that capture performance across relevant particle sizes, which helps when the site has specific air quality demands or unusual dust loads.

Less guesswork during replacement

When an older EN 779 label is all you have, it can be tempting to search for a close match and move on. But that can lead to under-specifying or over-specifying the replacement. Either outcome can create avoidable issues with pressure drop, fitment or maintenance workload.

More useful conversations with suppliers and engineers

Using ISO 16890 terminology makes it easier to discuss system intent with a mechanical services engineer, building owner or maintenance team. If the site also needs to align with ventilation requirements, the relevant building and system requirements should be confirmed with the mechanical services engineer or building owner, including any reference to AS 1668.2:2024.

A practical way to choose the right replacement filter

If you are dealing with a legacy EN 779 specification, use a step-by-step approach based on the system rather than the label alone.

• •Confirm the filter dimensions and construction
• •Identify the stage of filtration in the system
• •Check the current product’s ISO 16890 class and performance data
• •Review available space and airflow resistance in the air handling unit
• •Consider site dust load and how often the system is inspected
• •Follow the filter and equipment manufacturer instructions
• •Monitor pressure drop where gauges are fitted

Inspection frequency depends on the system, site conditions and dust load. A busy plant room, welding area, food production space or coastal site can behave very differently from a low-dust office environment.

Some filters are designed to be washable - check the product instructions before cleaning or reusing any product.

If you are also specifying filters for different sectors, our industries we supply page may help you narrow the application.

When to ask for custom or specialist support

Not every replacement is a straight swap. Older housings, unusual dimensions, retrofit projects and mixed-brand systems often need a more tailored approach.

That is where custom air filters can be useful, especially when the original legacy part is no longer available or the current system has been modified over time. A custom solution can help you match size, frame style and performance requirements more closely than forcing a near-fit product into service.

If you are unsure whether a legacy G3, G4 or F-class filter should be replaced with a particular ISO 16890 class, it is worth reviewing the application with the supplier before ordering.

Need help comparing old and new filter ratings?

Total Air Filtration is a family-owned air filter manufacturer and supplier based in Hillcrest, Brisbane QLD, established 2009. We can help you compare EN 779-era specifications with current ISO 16890 performance classes and supply the filters your system needs.

Call 07 3800 3448 or request a quote. If you would like to talk through a replacement or maintenance plan, you can also contact us.