Air filtration is absolutely essential for maintaining clean, safe environments in many different workplaces. Effective air filters remove dust, allergens, fumes, and other pollutants, improving air quality and protecting the health of you and your employees.
It’s important to understand, though, that not all filters perform the same function. Filter grades indicate their efficiency in trapping specific particle sizes and types, so choosing the right system is absolutely pivotal. Understanding these grades can also help you get the right balance between performance, cost, and efficiency.
Pre-Filters Capture Large Particles
Pre-filters are the first line of defence in air filtration. They trap larger particles like dust, lint, and hair, preventing finer filters from clogging too quickly. Sometimes referred to as coarse or primary filters, they’re usually rated as G1–G4 under the old EN 779 system or ISO Coarse in the newer ISO 16890 standard.
What that means in simple terms is that a G4 pre-filter, for instance, captures around 90% of large dust particles, while an ISO Coarse 70% filter removes 70% of particles.
Pre-filters are used in HVAC systems, industrial dust extraction, and air purifiers. In industrial settings, they protect expensive downstream filters from large debris like sawdust, and they’re also excellent at catching pet hair and dust. Their role is especially crucial in extending the lifespan of high-efficiency filters and maintaining proper airflow.
HEPA Filters Capture Finer Particles
HEPA (High-Efficiency Particulate Air) filters are designed for high-performance air purification. A HEPA filter captures at least 99.97% of particles as small as 0.3 microns, including pollen, bacteria, smoke, and some viruses. Under the EN 1822 standard, HEPA filters are classified as H13 or H14, with efficiencies of 99.95% and 99.995%, respectively.
HEPA filters are widely used in hospitals, cleanrooms, vacuum cleaners, and some high-end air purifiers. Industrial fume extraction systems, like those you might see used in soldering or laser marking, also rely on HEPA filters to trap fine dust and smoke. Because they can clog quickly, though, they’re often paired with pre-filters to remove larger particles first, which gives them a longer lifespan and more consistent performance.
Activated Carbon Filters Remove Odours and Fumes
Unlike particle filters, activated carbon filters remove gaseous pollutants, including volatile organic compounds (VOCs), odours, and chemical fumes. These filters use adsorption, where gas molecules bond to the internal surface of the carbon filter.
The science here gets complicated, but essentially, a small amount of activated carbon can have an internal surface area equivalent to several football fields, allowing it to trap huge amounts of airborne chemicals.
You’ll see activated carbon filters in use in kitchen range hoods, industrial chemical fume extractors, and air purifiers to remove smoke, solvent vapours, and unpleasant odours.
Since they work differently from HEPA or pre-filters, they’re sometimes used in tandem to create a multi-stage filtration system. Unlike HEPA filters, carbon filters aren’t assigned a numerical efficiency grade but are instead rated based on their capacity to absorb specific chemicals and odours.
What Are the Filter Grade Standards?
Essentially, there are three major standards that are used to define air filter efficiency:
ISO 16890 (Current International Standard)
ISO 16890 was introduced in 2016 and categorizes filters based on their ability to capture PM10, PM2.5, and PM1 particles. A filter labelled ISO ePM1 80% removes 80% of particles 1 micron or smaller (0.0001 millimetres). This system provides a more realistic assessment of how filters perform in everyday environments.
EN 779 (Older European Standard, Replaced by ISO 16890)
EN 779:2012 classified filters as G1–G4 (coarse) and M5–F9 (fine) based on their efficiency in trapping 0.4-micron particles. While now obsolete, many manufacturers still reference these grades. For example, an F9 filter under EN 779 captured over 95% of fine particles, making it suitable for demanding air quality applications.
EN 1822 (European Standard for HEPA and ULPA Filters)
EN 1822 applies to EPA, HEPA, and ULPA filters, grading them from E10 (85% efficiency) to U17 (99.999995% efficiency). H13 and H14 HEPA filters fall within this classification, ensuring nearly complete removal of fine particulates. These filters are critical in medical, pharmaceutical, and microelectronics industries, where ultra-clean air is required.
How Do I Know Which Filter Grade is Right for My Business?
Selecting the right filter depends on a few key factors.
Identify the Contaminants
Establish whether the main concern is dust, allergens, chemical fumes, or odours. Coarse dust requires pre-filters, fine particulates need HEPA filters, and gaseous pollutants demand activated carbon filtration. For example, if you’re a carpenter with a woodworking facility, you’ll need pre-filters and fine filters for sawdust, whereas if you’re working with solder fumes, you’re more likely to require HEPA and carbon filters for smoke and chemical vapours.
Air Quality Requirements
Industries with strict air quality standards, such as healthcare and pharmaceuticals, require HEPA filtration (H13 or H14). Offices and other workplaces might benefit from True HEPA filters for allergens. It’s important to remember that if compliance with ISO 16890 or EN 1822 is necessary, choosing filters that meet these standards is essential.
Want to Find Out More about Filter Grades?
We understand that getting to grips with filter grades can feel complicated. If you need guidance on which options best suit your requirements, then we’re on hand to help.
We partner with leading manufacturers, like Donaldson BOFA, to provide reliable, high-performance filtration systems that work across industries. If you need anything from a small solder fume extractor to a large-scale dust control system, we can help identify the best solution. For expert advice on selecting the right filters and extraction systems, contact us today.
FAQs
What is a pre-filter, and why is it important?
A pre-filter captures large dust and debris, protecting finer filters and extending their lifespan.
How often should HEPA filters be replaced?
Typically, every 6-12 months, depending on usage and dust levels.
Do carbon filters remove dust?
No, they remove gases and odours. HEPA or pre-filters handle dust.
How do I know which filter grade I need?
It depends on the contaminants present. ISO 16890 and EN 1822 ratings help guide selection. Contact an expert for more guidance.
