What Is ISO 16890? Understanding ePM1, ePM2.5 and ePM10 Ratings

If you are comparing air filters for a plant room, office fit-out or industrial site, ISO 16890 can be confusing at first glance. The good news is that the standard is based on a simple idea: how well a filter captures particles of different sizes in real-world air.

This guide explains what the ratings mean, how to read the particle classes, and what to check when comparing products.

What ISO 16890 is trying to measure

ISO 16890 is a test and classification standard for air filters used in general ventilation systems. Instead of using older class names alone, it groups performance by the size of particles the filter captures.

In plain English, the standard asks: how much of the dust, lint, pollen, smoke-like particles and other airborne material in this size range does the filter remove from the air passing through it?

That matters because not all dust is the same. Larger particles behave differently from finer particles, and different sites need different levels of capture depending on the application, the ventilation system and the environment.

The rating is not a promise that a filter will suit every system. It is one part of the selection process, alongside pressure drop, airflow, fit, frame type and the requirements of the equipment or building.

Understanding the ePM ratings

The letters and numbers in ISO 16890 are easier to read once you know the pattern.

What does ePM mean?

ePM means the filter’s efficiency for an airborne particulate matter size range.

The number that follows shows the particle range being considered:

• •ePM1 relates to finer particles around 1 micrometre and below
• •ePM2.5 relates to particles around 2.5 micrometres and below
• •ePM10 relates to particles around 10 micrometres and below

A filter may be described as, for example, ePM1-rated if it captures a defined proportion of particles in that smaller size range under the standard test method.

What the particle classes mean in practice

A useful way to think about the classes is by size:

• •ePM10 covers larger fine dust and many visible airborne particles
• •ePM2.5 covers smaller particles that can stay airborne for longer
• •ePM1 covers very fine particles, which are harder to capture and often need a more efficient filter stage

For many commercial ventilation systems, the choice comes down to the air quality target, the amount of outdoor dust being brought into the building, and how much resistance the system can handle.

How to compare filters under ISO 16890

When comparing products, look beyond the headline rating and check the full specification.

Compare the same particle class

A filter listed as ePM10 is not directly comparable with one listed as ePM1 unless you are looking at the same class. The class itself tells you what size range is being measured.

If you are comparing different products, make sure they are all rated using the same ISO 16890 class so you are looking at like-for-like performance.

Check the pressure drop

A filter that captures finer particles often creates more resistance to airflow. That does not mean it is the wrong choice, but it does mean the system needs to be checked carefully.

Look at:

• •initial pressure drop
• •recommended final resistance or change-out point
• •available fan capacity
• •whether the system can maintain airflow as the filter loads with dust

If gauges or differential pressure sensors are fitted, pressure drop monitoring is one of the best ways to judge when a filter needs attention.

Look at the full construction

The frame, media, seal and filter depth all matter. Two products with similar ISO 16890 ratings may behave differently in the field if one is poorly sealed, incorrectly fitted or not suited to the housing.

It also helps to confirm:

• •filter dimensions and exact fit
• •frame material
• •pleat spacing and media depth
• •whether the product is intended for pre-filtration, medium filtration or final filtration in your system

If you are unsure how to measure an existing filter, see how to measure an air filter.

ISO 16890 and older filter ratings

Many Australian buyers will still see older terms such as EN 779 classes or MERV ratings on drawings, legacy documents or product discussions. Those systems are not a direct one-to-one match with ISO 16890.

That means you should avoid assuming that a label from one standard automatically equals a label from another. The safest approach is to compare the actual ISO 16890 performance data, the intended application and the system requirements.

In Australia, you may also come across references to AS 1668.2:2024 for ventilation design and operation. If a project has specific compliance or performance requirements, confirm them with the mechanical services engineer or building owner.

When ISO 16890 matters most

This standard is especially useful when you are selecting filters for sites where outdoor air quality, dust load or internal cleanliness expectations vary.

It can be particularly relevant for:

• •office and commercial HVAC systems
• •schools and community buildings
• •warehouses and distribution centres
• •factories and process areas
• •hospitals and healthcare-related environments, where site-specific requirements need careful review
• •any site where the mechanical system must balance airflow and particle capture

If your site has unusual dust conditions, custom-sized housings or a mixed ventilation setup, a standard off-the-shelf product may not be the best fit. In that case, custom air filters can be worth considering.

Practical tips for facility managers and contractors

To make a better buying decision, keep these points in mind:

• •match the filter to the housing and airflow requirements
• •compare the same ISO 16890 class, not just the marketing description
• •check whether the filter is being used as a pre-filter, main filter or final stage
• •monitor pressure drop where possible
• •inspect the filter based on the system, site conditions and dust load rather than using a fixed calendar schedule
• •follow the filter and equipment manufacturer instructions for installation, inspection and replacement

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

If your site uses multiple stages, our products can help you compare options across pre-filters, panel filters and other commercial air filtration formats.

Choosing the right filter for your application

There is no single ISO 16890 rating that suits every system. A good choice depends on what the building needs to do, how much dust is present and what the system can handle without losing airflow.

For some systems, a coarser ePM10 filter may be the practical starting point. For others, an ePM2.5 or ePM1 option may be more suitable where finer particle capture is required and the system is designed for the added resistance.

If you are unsure, it helps to work from the equipment rather than the label alone. Check the existing filter dimensions, the housing, the airflow, the available fan capacity and the system documentation before ordering replacements.

If you need support for a large site or a specific ventilation arrangement, filter servicing and commercial filter servicing can also help keep the system operating as intended.

Need help selecting an ISO 16890 filter?

Total Air Filtration is a family-owned air filter manufacturer and supplier based in Hillcrest, Brisbane QLD, and we can help you choose or make the right filter for your system. Call 07 3800 3448 or request a quote.

If you would like to discuss a project, you can also contact us or review the industries we supply.