What Is the Most Penetrating Particle Size (MPPS)? Why Is It Important?

Learn why MPPS is a vital component in helping you find the best solution for your indoor air quality problems.

In today’s COVID-19 environment, there is much discussion about air quality. Keeping a building free from particulates and pathogens is an essential step toward keeping your staff and customers safe and healthy.

As a facility manager, you may have been tasked with determining the most effective method for air filtration and facility cleanliness in your building. While researching clean air solutions, you probably came across the term MPPS or “most penetrating particle size.” 

Since MPPS is a critical consideration in the air quality industry, filtration companies have spent countless hours and gone to great expense to find a way to stop particles of a specific size from polluting the air. 

With that said, a discussion of MPPS is vital in helping you find the best solution for your air quality problem. This blog will explain what MPPS is and why building managers and owners, such as yourself, need to understand it. Read on to learn more about why MPPS matters to you and your facility.

Most Penetrating Particle Size (MPPS)

MPPS refers to the size of the particles that most easily pass through a filter, whether the filter is infiltration or air purification system. According to the Environmental Protection Agency (EPA), for instance, a high-efficiency particulate air (HEPA) filter can remove 99.97% of particles with a size of 0.3 microns (or 300 micrometers).

An MPPS of 0.3 microns is the worst case; ironically, many filters are more effective at capturing particles smaller or larger than this, but a 0.3-sized particle regularly gets by basic filtration. Using 0.3 microns as the MPPS measures the worst-case efficacy of the filter.

For reference, particles of about 0.3 microns include:


Particle size is not necessarily a determinant of the harm it can cause: MPPS can cause as much—or even more—health issues as smaller or larger particles. 

For example, 0.3-micron particles are more likely to get lodged in lung tissue when inhaled. As a result, health problems from excess inhalation can occur, including headaches, cancer, and cardiovascular disease. In addition, dust mites, pollen, pet dander, and mold have been known to exacerbate asthma and cause allergy-related attacks.

Airborne Particulate Capture On Air Filter
Airborne Particulate Capture On Air Filter

What Is a Micron?

When we talk about air particles and air quality, we usually refer to particles measured in “microns.” Since air filter and air purification companies (and other industry professionals) commonly refer to microns, it is important to know what a micron is. 

micron is 1/1000 nanometers (1/25,000 of an inch) and is considered a fine particle size. In comparison, one hair from your head is roughly 70 microns in diameter. The average debris and dust that humans can see are about 25 microns. While 0.3-micron particles are invisible to the human eye (30 times smaller than your hair), they can still cause harmful health effects.

Why Do Air Purifier Companies Always Reference 0.3 Micron Size?

The 0.3-micron particle and particles ranging from 0.3 to 10 micrometers are the size that will most likely pass through a filter. MPPS can vary based on the type of filter and other factors, including humidity, the medium type, the particle shape, and the particle’s charge. Unfortunately, many air particulates are in the 0.3- to 10-micron range. 

In essence, the 0.3-micron size is the troublemaker in the air purification and air filtration space. Suppose the air filter or air purifier can only capture a small percentage of particles sized 0.3. In that case, that means many harmful particles are getting through, including common ones and ones known to cause health conditions, including those listed above.

Why Is the MPPS so Important?

As a facility manager, you must pay attention to the MPPS—the particle size most likely to cause health problems for your building inhabitants, as they can easily be inhaled and irritate breathing passages. Particles sized 0.3 microns include dust, mold or fungus, tobacco smoke, and chemicals; they are the most likely culprit in “sick building syndrome” (SBS).

The EPA defines sick building syndrome as when “building occupants experience acute health and comfort effects that appear to be linked to time spent in a building, but no specific illness or cause can be identified.” 

Sick building syndrome, which affects an estimated 30 percent of new or remodeled commercial buildings, can negatively impact a business’s operation and productivity. For instance, one study[TB3]  determined that sick building syndrome was responsible for an annual productivity loss ranging from $50 million to $100 million in 2002.

By upgrading your heating, ventilation, and air conditioning (HVAC) induct or filtration; you can improve the air purity in your building, keep occupants healthy, and maintain your business’s productivity. However, if upgrading is not currently an option, a portable air purification system is ideal for improved air quality. 

Can a HEPA Filter or MERV-13 Filter Help? 

Suppose a filter or air purifier cannot capture a large portion of the 0.3 micron-sized particles. In that case, consumers are less likely to purchase the product, believing—correctly—that the device will not adequately clean the air. Consumers want certainties, and the only way to guarantee anything in terms of the 0.3 micron-sized particle is to go with a True HEPA or Absolute HEPA filter. 

High-efficiency particulate air filters (HEPA) are mechanical filters designed to best capture MPPS. In a worst-case scenario, HEPA filters can capture particles 0.3 microns in size approximately 99.97% of the time (or better). Plus, they work best with activated carbon pre-filters. Efficacy is one of the main reasons why HEPAs are so popular. Previous air filters could not capture the MPPS as well as a True HEPA. 

Another way to find an air filter that can effectively capture MPPS is by using the Minimum Efficiency Reporting Value, or MERV rating. MERV is a scale developed by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) to rate filters based on their effectiveness at trapping specific particles. The MERV system can help consumers get a good comparison of filter performance. 

Dirty Used MERV HVAC Filter
Overused And Contaminated MERV HVAC Filter

Breakdown of MERV Rating And Efficiency From The EPA

Finding the Right Filter to Capture MPPS

There is a lot that goes into finding the right filter for your needs. For example, even based on the MERV rating scale, you can see filters rated MERV 16 cannot capture microns sized 0.3 as effectively as the HEPA can. 

The EPA still recommends MERV 13 or True HEPA as one of the most effective filter ratings outside of HEPA. You may need to ensure your HVAC system has a True HEPA or Absolute HEPA filter. 

However, some older systems do not work appropriately with MERV filters, so you may need a multi-layered option—for example, an air purification induct. You may also need to investigate portable air purification technologies.  

Portable air purifiers, like the Hydroxyl Blaster, Beyond Air Guardian, and Pure & Clean all provide portable True HEPA protection and 0.3-micron capturing technology, so you can ensure your facility is protected against the dangerous MPPS that could harm your workers or customers. These products are the perfect solution for sick building syndrome or to help with facility reopening during the COVID pandemic.  

Your air quality controls will also have to follow guidelines from the Occupational Safety and Health Administration (OSHA), the National Institute for Occupational Safety & Health (NIOSH), the EPA, and any other guidelines related to facility sustainability. 

We understand that all the different guidelines can be confusing. Reach out to a professional at Sanalife for an air quality product assessment and help with finding a customized solution for ensuring your building has clean air.

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