High-Efficiency Particulate Air (HEPA) filters are known for their ability to remove 99.97%–99.99% of airborne particles equal to or smaller than 0.3 microns in size. These filters are widely used in various settings, including homes, offices, and medical facilities, to improve indoor air quality and protect individuals from allergens, bacteria, and viruses. This article will explore the efficiency of HEPA filters in different settings, compare them to other air purifiers, and discuss the benefits of using HEPA filters.
HEPA Filter Efficiency in Different Settings
High Efficiency Particulate Air (HEPA) filters are a type of pleated mechanical air filter designed to remove at least 99.97% of dust, pollen, mold, bacteria, and any airborne particles with a size of 0.3 microns (µm). This specification corresponds to the most penetrating particle size (MPPS), meaning particles that are larger or smaller are trapped with even higher efficiency.
HEPA Filters in Isolation Rooms
A study that looked at how well portable HEPA filters worked in a temporary isolation room discovered that an anteroom, HEPA filtration, and negative pressure stopped almost 98% of aerosols from moving to the corridor next to it. This demonstrates the efficiency of HEPA filters in reducing the spread of airborne contaminants in various settings.
The study also found that the best location for a single portable air purifier unit is inside the isolation room and near the patient’s bed. This is because the HEPA filter unit was most effective when placed inside the isolation space next to the patient bed.
HEPA Filters and COVID-19
When used properly, air cleaners and HVAC filters, including those with HEPA filters, can help reduce airborne contaminants, including viruses such as COVID-19, in a building or small space. However, air cleaning or filtration alone is not enough to protect people from COVID-19. When used along with other best practices recommended by CDC and other public health agencies, including social distancing and mask wearing, filtration can be part of a plan to reduce the potential for airborne transmission of COVID-19 indoors.
HEPA Filters and Particulate Pollution
The filtering efficacy of air purifiers, including those with HEPA filters, is directly proportional to the Clean Air Delivery Rate (CADR) value. The higher the CADR value, the higher the filtering efficiency of the air purifiers.
The study also found that HEPA filters were more effective on small particles than large ones. Diffusion removes the smallest particles, whereas the other three mechanisms—interception, inertial impaction, and sieving—work better on large particles.
- HEPA filters can theoretically remove at least 99.97% of dust, pollen, mold, bacteria, and any airborne particles with a size of 0.3 microns (µm).
- An anteroom, HEPA filtration, and negative pressure worked together to keep almost 98% of aerosols from moving to the corridor next to the temporary isolation room.
- Air cleaners and HVAC filters, including those with HEPA filters, can help reduce airborne contaminants, including viruses such as COVID-19, in a building or small space when used properly.
- The filtering efficacy of air purifiers, including those with HEPA filters, is directly proportional to the Clean Air Delivery Rate (CADR) value.
HEPA filters are highly effective in capturing particles and reducing the spread of airborne contaminants in various settings. However, they should be used in conjunction with other best practices for optimal results.
HEPA Filters vs. Other Air Purifiers
When it comes to improving indoor air quality, the choice of air purifiers can be overwhelming. Two of the most common types are HEPA filter-based air purifiers and electrostatic air purifiers. Understanding the differences between these two can help you make an informed decision that best suits your needs.
HEPA Filter-Based Air Purifiers
HEPA, an acronym for “high efficiency particulate air [filter]”, is a type of pleated mechanical air filter. These filters are designed to capture at least 99.97% of dust, pollen, mold, bacteria, and any airborne particles with a size of 0.3 microns (µm). This makes them highly effective at improving indoor air quality.
To make the system work better, HEPA filters are often used with other filters, like pre-filters or activated carbon filters, and technologies, like UV-C light/PCO technology and negative ionization. They are commonly used in various settings, including schools, government buildings, industrial services, and offices, to reduce air pollution, improve air quality, reduce sickness, and eliminate harmful viruses.
The maintenance of HEPA filters involves periodic cleaning and filter replacement as per the manufacturer’s recommendations. Some air purifiers offer filter subscription plans, making it easy to replace the old filter after six to twelve months of regular use.
Electrostatic Air Purifiers
Unlike HEPA filters, electrostatic air purifiers do not use filters. Instead, they work with static electricity to charge particles inside the air purifier. The charged particles stick to the sides of the internal filtration system and are removed from your indoor air.
While the idea of never having to replace filters may seem appealing, the efficiency of electrostatic air purifiers begins to decrease as minute particles begin collecting in the filtration system. Cleaning these systems can be quite complicated, requiring disassembly of the internal filtration system and sometimes using specified cleaning fluids for the best results.
Comparing HEPA and Electrostatic Air Purifiers
When comparing the two, HEPA filters have a clear edge over electrostatic air purifiers. The first-pass efficiency rate, which is the amount of particles captured by the air purifier during the first air exchange, is higher for HEPA filters. They capture 87–99% of particles during the first air exchange, while electrostatic air purifiers have a 60–80% first-pass efficiency rate.
Moreover, HEPA filters are more user-friendly. They require less maintenance and are easier to clean compared to electrostatic air purifiers. Simply replacing the old filter ensures optimal air quality.
On the other hand, electrostatic air purifiers require a longer amount of time to improve your indoor air quality and must be run at a lower speed to be most effective.
While both HEPA and electrostatic air purifiers have their merits, HEPA filters are generally more effective and easier to maintain. They provide a higher first-pass efficiency rate and require less maintenance compared to electrostatic air purifiers. Therefore, if you’re looking for an air purifier that is efficient, easy to maintain, and effective at improving indoor air quality, a HEPA filter-based air purifier would be a superior choice.
Remember, the choice of an air purifier should be based on your specific needs and circumstances. Always consider factors such as the size of the space, the type of pollutants you want to remove, and your budget before making a decision.
Benefits of HEPA Filters
- Allergy and Asthma Relief: HEPA filters can effectively capture allergens such as pollen, pet dander, and dust mites, providing relief for individuals suffering from allergies and asthma.
- Protection Against Airborne Infections: HEPA filters can capture bacteria and viruses, including the SARS-CoV-2 virus responsible for COVID-19. This helps reduce the risk of airborne infections in various settings, including hospitals and homes.
- Improved Indoor Air Quality: By removing a wide range of airborne particles, HEPA filters contribute to better indoor air quality, which can lead to improved overall health and well-being.
In conclusion, HEPA filters offer numerous benefits in terms of efficiency, protection against allergens and airborne infections, and improved indoor air quality. They outperform other air purifiers in capturing a wide range of airborne particles and are a valuable addition to homes, offices, and medical facilities.