Popular Search Terms:
  • Fellowes Shredder
  • Volo Wall System
  • Bulldog Shredder
  • LX Series

From MERV To HEPA: The Different Types Of Air Purification Filters

Common Air Purifier
Filters, Including HEPA

3-Stage Air
Filtration

UV Light
Technology

MERV
Filters

Finding An Air Filtering
Solution That Works

When it comes to air filters, you’re likely to hear a wide range of terms.

MERV, HEPA, True-HEPA and HEPA-13 are just a few.

While some of these filters are used either in HVAC or air purification systems to remove the harmful airborne particles inside offices, hospitals, schools, restaurants, homes and many other places, there are big differences between these types of air filters.

Whether you realise it or not, the air purification filters in your workplace or home can make a huge difference to your indoor air quality and ultimately, your health.

The performance of these filters determines which, and how effectively, pollutants are removed from your indoor air.

Common Air Purifier Filters, including HEPA

Pre-Filter

The pre-filter used in Fellowes air purifiers actively removes large particles such as visible dust, pet dander, or pollen, thereby protecting the lifespan of other filters in the unit.

Activated Carbon Filters

Activated carbon filters adsorb gases, odours and volatile organic compounds (VOCs) from indoor air.

Commercial-grade carbon particle filters have more carbon content and surface area than typical consumer-grade carbon-impregnated weaves. This means they are designed to keep performance during their defined lifespan.

While carbon filters remove odours and VOCs, they do not on their own remove dust and other allergens, so are best when usedin air purifiers alongside HEPA filters where both types of filter work together to remove the widest possible range of pollutants.

HEPA (High-Efficiency Particulate Air) filters

HEPA air filters are a type of pleated mechanical air filter that is tested and certified to capture at least 99.95% of particles that are 0.3 microns or more in diameter.

Made of a dense web of fibres that trap contaminants, HEPA filters can catch pollen, dirt, dust, mould spores, bacteria and viruses, among other harmful pollutants.

There are different grades of HEPA filters. The higher the grade, the higher the performance. Filters that are graded as H10 to H12 filters are known as True HEPA filters.

True HEPA Filters

True HEPA air filters are tested and certified to capture at least 99.97% of particles as small as 0.3 microns.

This performance is regularly proved in laboratory condition tests, where True HEPA filters have 10,000 0.3-micron sized particles blown through them. Of these 10,000 particles, only three, at most, can pass through the HEPA filter.

True HEPA filters are excellent at capturing nearly all particles of pollen, mould, and bacteria, and are ideal for people with allergies or asthma, and in any environment where indoor air quality matters. Some True HEPA Filters are treated with Antimicrobial Treatment which prevents microbes from growing on the filters.

HEPA 13 filters

HEPA 13 is a premium-grade HEPA filter that can capture 99.95% of microscopic particles of 0.1 microns or more.

The H13 filter has become particularly important since the covid pandemic when researchers found that virus particles could be as small as 0.1 microns¹, and covid particles ranged from 0.1 to 0.5 microns.

This makes HEPA 13 filters ideal for capturing these extremely tiny, but harmful particles in any workplace that wants to protect people’s health, reduce the risk of colds and flu spreading and minimise the disruptive impact of any future virus outbreaks.

HEPA H13 filters are particularly suitable for healthcare and education environments, where high numbers of people are either vulnerable, or can easily pass viruses through their wider communities.

3-Stage Filtration

By combining these 3 filters (pre-filter, carbon, and H13 True HEPA) you can increase the effectiveness of each filter and your air purification system. The Fellowes 3-stage filtration process, found in our state of the art Array Air Purifiers, effectively removes at least 99.95% of particles as small as 0.1 microns, including allergens, such as pollen, dust, pet dander, and smoke.

1. Pre-Filter

Captures large particles

2. Activated Carbon Filter

Adsorbs odours and Volatile Organic Compounds (VOCs)

3. True HEPA Filter

Captures small particles as small as 0.1 microns

Air Filtration Diagram Air Filtration Diagram

UV light technology

UV light technology uses ultraviolet light to kill or inactivate bacteria, viruses, and other micro-organisms.

Although they are not a traditional ‘physical’ filter and do not trap dust and other particles, UV bulbs are often used as part of a wider air quality management system, alongside HEPA filters. This provides an extra safeguard against viruses and bacteria, particularly where occupants may have compromised immune systems.

Discover the Fellowes Array Recessed UV Air Purifier

MERV (Minimum Efficiency Reporting Values filters)

MERV filters are generally used in traditional HVAC systems to improve indoor air quality. Though they are designed to capture particles, they are not effective at removing gases, odours, or VOCs.

MERV filters are rated on a scale from 1 to 16 based on their ability to capture particles between 0.3 and 10 microns in size.

The higher the MERV rating, the better the filter is at trapping specific types of particles.

MERV 8 to MERV 13 filters have been traditionally used in homes and many workplaces, while MERV 14-16 filters are intended for hospital and other healthcare environments.

However, MERV filters cannot achieve the performance of HEPA filters, with even the very highest-grade MERV 16 filters capturing, at best, 95% of particles that are 0.3 microns and above in diameter. This MERV rating chart, published by the Environmental Protection Agency², details the performance of the different MERV filters, compared to HEPA filters:

MERV Rating
Average Particle Size Efficiency in Microns
1-4
3.0 - 10.0 less than 20%
5
3.0-10.0 greater than or equal to 20%
6
3.0-10.0 greater than or equal to 35%
7
3.0-10.0 greater than or equal to 50%
8
1.0-3.0 greater than or equal to 20%
3.0-10.0 greater than or equal to 70%
9
1.0-3.0 greater than or equal to 35%
3.0-10.0 greater than or equal to 75%
10
1.0-3.0 greater than or equal to 50%
3.0-10.0 greater than or equal to 80%
11
0.30-1.0 greater than or equal to 20%
1.0-3.0 greater than or equal to 65%
3.0-10.0 greater than or equal to 85%
12
0.30-1.0 greater than or equal to 35%
1.0-3.0 greater than or equal to 80%
3.0-10.0 greater than or equal to 90%
13
0.30-1.0 greater than or equal to 50%
1.0-3.0 greater than or equal to 85%
3.0-10.0 greater than or equal to 90%
14
0.30-1.0 greater than or equal to 75%
1.0-3.0 greater than or equal to 90%
3.0-10.0 greater than or equal to 95%
15
0.30-1.0 greater than or equal to 85%
1.0-3.0 greater than or equal to 90%
3.0-10.0 greater than or equal to 95%
16
0.30-1.0 greater than or equal to 95%
1.0-3.0 greater than or equal to 95%
3.0-10.0 greater than or equal to 95%
HEPA (High Efficiency Particulate Air) filter
99.97% of particles in the 0.3-micron range Particles that are larger or smaller than 0.3 microns are captured with a greater than 99.97% efficiency

Interestingly, HEPA filters are actually more effective either side of the worst-case scenario of 0.3 microns, which is known as the most penetrating particle size (MPPS). Particles that are larger or smaller are trapped with even higher efficiency.

There are also airflow issues with higher graded MERV filters, because MERV 13 and higher filters can significantly restrict airflow in HVAC systems.

This can cause HVAC systems to run more slowly, reducing their efficiency and increasing energy costs.

Learn more about whether your HVAC system is contributing to poor indoor air quality

Finding an air filtering solution that works

Most air quality experts agree that given a choice between MERV 13+ and HEPA filters, an air purifier with a HEPA filter is superior. Because they can filter out almost all harmful pollutants and viruses, HEPA filter-equipped air purification systems are especially important for air cleaning in higher risk healthcare environments, public settings, or any workplaces where people can easily pass viruses to one another.

Since Covid-19, there has been a growing expectation for air purifiers to filter out even the tiniest, and most health-damaging of particles, which includes Covid. To achieve this, HEPA-13 filters, working in an integrated air purification system with carbon filters and UV light technology, are the best and most effective solution for optimum health and safety.

Want to learn more about indoor air quality management? Download our Ultimate Guide to Indoor Air Quality Management for free today at:

Sources

  1. Minimum Sizes of Respiratory Particles Carrying SARS-CoV-2 and the Possibility of Aerosol Generation - PMC (nih.gov)
  2. What is a MERV rating? | US EPA

Operating as a fourth-generation family business establishes our cultural foundation. It’s a shared ideal among our team to align under our commitment to integrity and solidifying the relationships that matter most.

Our Family Heritage

Fellowes GIVE is a purpose-led corporate initiative in which we partner with organisations to help meet some of the most fundamental human needs in our local communities.

Our Give Initiatives

How we shape the world of work today has a profound impact on the world of tomorrow. By building sustainability and stewardship into every level of our organisation, we can protect the worklife potential of our children and grandchildren.

Our Sustainability Efforts