What is the Difference between MERV and HEPA Filters?

MERV stands for Minimum Efficiency Reporting Value, which is a rating system that measures the effectiveness of air filters by removing airborne particles in the air. The MERV rating scale ranges from 1 to 20, with a higher number indicating a more effective filter.

The rating system takes into account the filter’s capability to trap particles of different sizes, including dust, pollen, pet dander, and other contaminants. MERV ratings are determined by testing the filter’s efficiency when capturing particles of specific sizes and calculating an overall rating based on those results.

Below is the classification of what the different MERV ratings stand ranging from 1-16. Yet, MERV 17-20 was not specifically regulated. The reason why there is no regulation specifically for MERV ratings of 17-20 is that these ratings are typically used for specialized applications where extremely high levels of air quality are required, such as in hospitals, laboratories, and cleanrooms. The use of filters with MERV ratings in this range is generally considered to be a matter of choice rather than a regulatory requirement.

However, it’s important to note that there are other regulations and standards that may apply to these specialized applications, such as those related to the control of airborne contaminants in healthcare facilities or cleanrooms. In addition, building codes and other regulations may require certain minimum levels of filtration efficiency for HVAC systems, but they typically don’t specify a particular MERV rating. Instead, they may specify a minimum level of particle size that must be captured by the filter or a minimum level of overall filtration efficiency.

• MERV 1-4: These filters are typically used in residential systems and effective at capturing larger particles such as dust mites, pollen, and carpet fibers.
• MERV 5-8: These filters are more effective at capturing smaller particles such as mold spores and pet dander and are commonly used in commercial buildings and homes with pets.
• MERV 9-12: These filters are highly efficient at capturing smaller particles such as bacteria and tobacco smoke and are commonly used in hospitals and other healthcare environment.
• MERV 13-16: These filters are among the highest-rated being able to capture particles as small as viruses and microscopic allergens. They are commonly used in cleanrooms and highly sensitive environments such as testing labs, semiconductor plants, etc.

It’s important to note that while a higher MERV rating can indicate better filtration, and it can also lead to reduced airflow and strain in your HVAC system. It’s recommended to consult with a professional team or personnel  to determine the appropriate MERV rating for your specific requirements.

What is HEPA air filters? How is the rating?

HEPA is the acronym of High-Efficiency Particulate Air, and a HEPA filter is a type of air filter designed to capture very small particles such as pollen, dust, and smoke. HEPA filters are commonly used in air purifiers, vacuum cleaners, and HVAC systems. 

HEPA filters are rated based on their ability to capture particles of various sizes. The rating system used for HEPA filters is called the Minimum Efficiency Reporting Value (MERV), which ranges from 1 to 20. The higher the MERV rating, the more efficient the filter is at capturing smaller particles. 

HEPA filters typically have a MERV rating of 17 to 20 (see below for more details), which means they can capture particles as small as 0.3 microns with an efficiency of 99.97%. To put that in perspective, a human hair is about 50 to 100 microns in diameter, and a particle as small as 0.3 microns is too small to be seen by the naked eyes.

• MERV 17: This rating is typically found on high-efficiency particulate air (HEPA) filters. Filters with a MERV 17 rating can capture particles as small as 0.3 microns with an efficiency of 99.97% or higher. These filters are used in hospitals, clean rooms, and other environments where very high air quality is required.
• MERV 18: Filters with a MERV 18 rating have a higher efficiency than MERV 17 filters and can capture particles as small as 0.3 microns with an efficiency of 99.99%. These filters are often used in clean rooms, research facilities, and other environments where even higher air quality is required.
• MERV 19: Filters with a MERV 19 rating can capture particles as small as 0.1 microns with an efficiency of 99.999%. These filters are used in very specialized applications, such as semiconductor manufacturing, where even the smallest particles can cause significant problems.
• MERV 20: This is the highest MERV rating currently available and is only used in the most specialized applications. Filters with a MERV 20 rating can capture particles as small as 0.1 microns with an efficiency of 99.999%. These filters are used in applications such as clean rooms for semiconductor manufacturing and pharmaceutical production.

It’s important to note that HEPA filters are not designed to capture gases or odors. For this reason, some air purifiers also include additional filters, such as activated carbon filters, to address these issues.

Filtration rating table for MERV vs. HEPA

MERV (Minimum Efficiency Reporting Value) and HEPA (High Efficiency Particulate Air) are two different rating systems for air filters. While MERV ratings are based on the ability of an air filter to remove large particles from the air, HEPA ratings are based on the ability of an air filter to remove smaller particles from the air. Here is a table comparing the filtration rating of MERV and HEPA:

In general, HEPA filters are more effective than MERV filters at capturing smaller particles, such as bacteria, viruses, and allergens. HEPA filters have a minimum efficiency of 99.97% for particles 0.3 microns or larger, while MERV filters have a maximum efficiency of 95% for particles 0.3 to 1.0 microns in size. However, MERV filters are more commonly used in residential and commercial HVAC systems, as they provide adequate filtration for most applications at a lower cost.

How to distinguish the filtration rating in between MERV & HEPA?

MERV (Minimum Efficiency Reporting Value) and HEPA (High-Efficiency Particulate Air) are both used to measure the effectiveness of air filters, but they have different rating systems.

MERV ratings range from 1 to 20, with higher numbers indicating better filtration efficiency. MERV ratings indicate how well the filter can capture particles of different sizes, including pollen, dust mites, and pet dander. However, MERV ratings do not measure a filter’s ability to capture tiny particles like viruses and bacteria.

HEPA filters, on the other hand, are highly efficient at capturing small particles. HEPA filters must capture at least 99.97% of particles that are 0.3 microns in size or larger. HEPA filters are often used in medical facilities, laboratories, and other environments where air quality is critical.

All in all, MERV ratings are used to measure a filter’s ability to capture larger particles, while HEPA ratings are used to measure a filter’s ability to capture small particles. If you need a filter that can capture very small particles, such as viruses, then a HEPA filter is likely the best choice. However, if you are mainly concerned with capturing larger particles like dust and pollen, a filter with a high MERV rating may be sufficient.