When purchasing air purifiers, HVAC units, and even vacuum cleaners, it's common to see the word HEPA emblazoned on the box. Is that a good thing? What does HEPA mean, exactly? What are the different grades? Does it even really matter?
What is HEPA?
The idea behind the development of HEPA--High-Efficiency Particulate Air--filters was born from gas masks worn by soldiers fighting in World War II, and later expanded during the Manhattan Project to prevent the spread of radioactive particles in the air. The standard that was developed by the U.S. Department of Energy was commercialized in the 1950's and is now common throughout the world.
HEPA standards require that a filter remove 99.97% of all particles greater than 0.3 microns from the air moving through it. To put it another way, if 10,000 particles move through the filter, only three are allowed to pass through.
Filters conforming to the HEPA standard trap a wide variety of contaminants, including those so small they are not visible to the naked eye. Counter-intuitively, the smallest particles are the ones most dangerous to human health. The smaller the particle, the deeper they are able to penetrate your lungs; the smallest particles can even enter your bloodstream. HEPA filters capture pollen, dirt, dust, moisture, bacteria (0.2-2.0 μm), virus (0.02-0.3 μm), and submicron liquid aerosol (0.02-0.5 μm)
Exposure to such particles can affect both your lungs and your heart. Numerous scientific studies have linked particle pollution exposure to a variety of problems, including:
- premature death in people with heart or lung disease
- nonfatal heart attacks
- irregular heartbeat
- aggravated asthma
- decreased lung function
- increased respiratory symptoms, such as irritation of the airways, coughing or difficulty breathing.
Different Grades of HEPA
There are not different types of HEPA filters: a filter either conforms to the HEPA standard, or it doesn't. This includes filters marketed as "HEPA-Like", which may look like HEPA filters externally but do not perform to the required standard. There are, however, different grades of HEPA filters, which range from H10 through H14. The higher the grade, the higher the performance.
H10 to H12 filters are sometimes known as "True HEPA" filters. They trap less particles than the higher grade filters. H13 and H14 are known as "medical grade" HEPA filters. These filter 99.95% and 99.995% of all particles down to 0.3 microns, respectively.
Medical Grade HEPA is used extensively in industries that require extremely clean environments, such as medical manufacturing facilities and electronics manufacture, because they have such a high particulate retention rate.
What should you choose?
In the past, due the manufacturing costs and fan design, it was prohibitively expensive to purchase H13 or higher HEPA filtration for your home or office. These days, prices have come down to the point where this technology is available to everyone for a reasonable price.
Some manufacturers use a lower grade of HEPA in order to maximize their CADR score, but taking into consideration the vast amount of industrial and manufacturing pollutants in the air it is wise to get the highest grade of HEPA affordably available.
When comparing different air purifiers from different manufacturers, it is essential to note what grade of HEPA filter is being used. Look for terms like "H13" or "Medical Grade" and stay away from anything being sold as "True HEPA" or "HEPA Like." Your family is worth it.
