Why Micron Size Matters: The Unseen Advantage of HEPA Filtration

It’s nothing new that airborne contamination poses major risks to patients and staff alike in a healthcare setting, but the size of individual particles in the air makes a big difference in the way that you will want to address them.  While some particles are large enough to get caught in a standard air filter, others are invisible to the naked eye and can only be captured through the use of specialized medical-grade filters. 

Facility managers must be vigilant in understanding the various types of airborne threats and the most effective ways to mitigate them. One of the most important considerations is the role of micron size in air filtration. Because different contaminants vary not only in their potential danger but also in their size, measured in microns, your choice of filter and filtration equipment can make or break your approach to indoor air quality (IAQ) and healthcare safety as a whole. 

Are you confident in your understanding of micron size and what it means for your infection control and IAQ efforts? Use this guide as a refresher to help you provide your facility with the highest level of safety.  

What is a Micron?

Firstly, understanding micron size is essential for anyone responsible for maintaining indoor air quality. A micron, or micrometer, is one-millionth of a meter. 

For some perspective, here are a few examples of common micron sizes:

• Human Hair Size: ~55-100 microns
• Pollen Size: 10 to 100 microns
• Mold Particle Size: 1 to 30 microns
• Bacteria Size: 0.3 to 60 microns
• Viruses Size: 0.004 to 0.1 microns
• Smoke Particles Size: 0.01 to 1 micron

Particles smaller than 10 microns are inhalable and can penetrate deep into the lungs, leading to various health issues. The smaller the particle, the more easily it can bypass the body's natural defenses.

Impact of Micron Size on Filtration Efficiency

Filters are rated based on the size of particles they can effectively capture. Therefore, knowing the sizes of common contaminants helps in selecting the appropriate filtration system. For instance, a filter that efficiently captures particles down to 5 microns may be suitable for dust but ineffective against bacteria and viruses.

In healthcare facilities, where the presence of bacteria and viruses is a significant concern, filters must be capable of capturing particles much smaller than those that cause issues in less sensitive environments. Selecting a filter without considering the specific micron sizes of harmful particles could result in inadequate air purification.

What is MPPS?

The Most Penetrating Particle Size (MPPS) is the particle size that is most difficult for a filter to capture. For HEPA filters, this is typically around 0.3 microns. Particles at the MPPS are small enough to follow airflow streams through the filter without being intercepted but large enough to avoid the random motion (diffusion) that aids in capturing even smaller particles.

This concept is crucial because filters are tested and rated based on their efficiency at the MPPS. A filter that performs well at the MPPS will generally perform even better at capturing both larger and smaller particles due to the mechanisms of impaction and diffusion.

HEPA Filters and MPPS

HEPA filters are specifically designed to target the MPPS. By achieving a 99.97% efficiency at capturing 0.3-micron particles, they provide a high level of protection against a wide range of contaminants. Interestingly, HEPA filters are even more efficient at capturing particles smaller than 0.1 microns due to the diffusion mechanism, which causes tiny particles to collide with gas molecules and become trapped.

Understanding MPPS helps in appreciating why HEPA filters are so effective and why they are the standard in environments where air purity cannot be compromised.

The Power of HEPA Filtration in Controlling Air Contamination

High-efficiency particulate air, or HEPA, filters, like those we offer here at HEPACART®, are widely known as the gold standard in their ability to trap ultra-fine particles, preventing them from recirculating into the air we breathe. Air purifiers equipped with HEPA filtration can effectively remove up to 99.7% of airborne particulate matter down to 0.3 microns in size, including dust, allergens, bacteria, mold particle size, and even smoke.   The U.S. Department of Energy HEPA regulation mandates that all HEPA filters meet this standard at a minimum.

Don’t Be Mislead By HEPA Alternatives

HEPA filters are uniquely suited and rigorously tested to clean the air in your medical facility to the highest degree. However, you must understand and choose your HEPA filter thoughtfully. There are plenty of misleading marketing terms out there that will aim to confuse your understanding of HEPA and non-HEPA filters. There is only one HEPA designation. Any HEPA filter that is advertised with any qualifier like “HEPA-like” or “HEPA-style” is NOT a genuine HEPA filter. The only designation that will give you certified HEPA filtration is “true HEPA” and this term only exists to help break through the marketing jargon.  With true, powerful HEPA filtration and industry-leading dependability your staff, and your facility’s patients have peace of mind. 

How HEPA Filters Work

HEPA filters are constructed from densely packed fibers that create a maze-like structure, which forces airborne particles to take a convoluted path. This increases the likelihood that contaminants will get trapped before they can circulate back into the air. By capturing 99.97% of particles at 0.3 microns, HEPA filters specifically target what is known as the most penetrating particle size (MPPS). This particle size is the most difficult to capture, making HEPA filters highly efficient at removing even the smallest airborne threats.

There are three primary mechanisms by which HEPA filters capture particles:

1. Interception: Particles following the airflow come within one radius of a fiber and adhere to it.
2. Impaction: Larger particles cannot avoid fibers by following the curving contours of the airflow and are forced to embed into them directly.
3. Diffusion: Very small particles, particularly those below 0.1 microns, collide with gas molecules, impeding their path through the filter and increasing the chance they'll be captured by interception or impaction.

HEPA vs. Other Filters

Not all air filters are created equal. Standard MERV filters, commonly used in many HVAC systems, can trap larger particles but struggle to capture smaller, more harmful contaminants. MERV filters are rated on a scale from 1 to 16, with higher numbers indicating the ability to capture smaller particles. However, even the highest-rated MERV filters (13-16) fall short of HEPA filters when it comes to filtering particles at the 0.3-micron level.

In critical environments like healthcare facilities, HEPA filters are the preferred choice of facility managers worldwide. They are specifically designed to protect against invisible threats, ensuring that the air remains as clean as possible.

HEPA Filters for Protection from Harmful Airborne Particles

0.3 Micron Particles and Health Risks

Particles around 0.3 microns pose significant health risks because they can penetrate deep into the respiratory system. Once inhaled, they can bypass the body's natural filtration mechanisms and settle in the lungs or even enter the bloodstream.

In healthcare facilities, the presence of such particles can lead to:

• Respiratory Infections: Bacteria and mold spores can cause infections, particularly in patients with weakened immune systems.
• Allergic Reactions: Allergens can trigger asthma attacks and other allergic responses.
• Long-Term Health Issues: Prolonged exposure to fine particles can lead to chronic respiratory diseases and other health complications.

HEPA Filters for Medical Facilities

Implementing HEPA filters in medical settings is not just a recommendation but often a regulatory requirement. True HEPA filters, classified as H13 or H14, meet stringent standards for air purification:

• H13 Filters: Capture 99.95% of particles at 0.3 microns.
• H14 Filters: Capture 99.995% of particles at 0.3 microns.

These filters are used in critical areas such as operating rooms, isolation rooms, and laboratories where maintaining a sterile environment is essential.

Practical Applications of HEPA Filtration: Improving Indoor Air Quality

HEPA Filtration in Healthcare

The benefits of HEPA filtration in healthcare settings are numerous:

• Infection Control: By removing airborne pathogens, HEPA filters reduce the risk of hospital-acquired infections.
• Dust Containment: During construction or renovation, HEPA filters prevent dust and debris from spreading to patient areas.
• Air Quality Improvement: Overall air quality is enhanced, contributing to faster patient recovery and better working conditions for staff.

How to Choose the Right HEPA Filter

To select the right HEPA filter, consider these 4 factors: 

• Facility Needs: Identify the specific contaminants prevalent in your environment, their micron size, and how to best capture the highest percentage of those contaminants. 
• Filter Classification: Choose between H13 and H14 filters based on the required level of filtration.
• MERV Rating: While HEPA filters are rated differently, understanding MERV ratings can help in pre-filter selection to extend the life of HEPA filters.
• Compliance Standards: Ensure that the filters meet regulatory requirements for your facility type.

Consulting with an air quality expert can aid in making informed decisions tailored to your facility's needs.

Maintaining Your HEPA Filtration Systems

Maintaining HEPA filters is key to sustained performance over the years. Over time, filters accumulate captured particles, which can lead to:

• Reduced Airflow: Clogged filters restrict airflow, making HVAC systems work harder and less efficiently.
• Decreased Efficiency: A saturated filter may allow particles to bypass filtration.
• System Strain: Overloaded filters can cause mechanical strain on ventilation systems.

Replacement Schedule

HEPA filters should be replaced according to manufacturer guidelines, which typically recommend replacing filters every 12 to 18 months, potentially more frequently — every 6 months — in high contamination areas.

Schedule regular inspections to help determine if your HEPA filters need to be replaced sooner due to unexpected contamination levels, traffic in the facility, or otherwise higher risk of infection or disease.

Proper Handling and Disposal

When replacing HEPA filters, it's important to handle them carefully to avoid releasing trapped contaminants back into the environment. Used filters should be sealed and disposed of according to local regulations, especially if they have captured hazardous materials.

Learn How a Cleaner Facility Starts with HEPA Filtration

Understanding the importance of micron size in air filtration is essential for maintaining healthy indoor environments, particularly in healthcare settings. By targeting specific micron sizes, facility managers can effectively remove harmful contaminants from the air, reducing health risks and enhancing the well-being of occupants.

HEPA filters offer unparalleled efficiency in capturing particles at the most penetrating particle size of 0.3 microns. Their implementation is a proactive step toward improving indoor air quality, ensuring that even the smallest and most harmful particles are removed from circulation.

Don't leave the quality of your facility's air to chance. Upgrade your filtration systems to true HEPA filters and take a significant step toward safeguarding the health of your patients, staff, and visitors. To learn more about how HEPA filtration can protect your facility and to make informed decisions about air purification, download our comprehensive HEPA vs. ULPA Guide today.