We all know that air pollution in cities and workplaces is hazardous to our health. But, quite often, the air inside our homes also contains harmful particles and allergens that can cause illness and trigger allergies.
We can take advantage of technology to help reduce exposure to the things that can cause coughs, sneezes, and asthma, or worse yet, create long-term health issues. Among the many filtration technologies, HEPA filtration is by far the most convenient and reliable way to fight airborne allergens and remove harmful particles from the air you breathe each day.
What Is a HEPA Filter?
A HEPA filter is a specific type of air filter, and the acronym “HEPA” stands for High-Efficiency Particulate Arresting. In order for manufacturers to claim that their air filters are HEPA, they must meet certain standards. The American Society of Mechanical Engineers states that a HEPA filter must be able to capture 99.97 percent of particles larger than 0.3 microns in diameter from the air that passes through the filter.
To give you a reference point for scale; a micron is one millionth of a meter, and a human hair is about 40-50 microns wide. Dust, pollen, spores and most bacteria are larger than the 0.3-micron diameter specified by ASME. A HEPA filter will trap particles that are larger and smaller than 0.3 microns, in diameter, but this size of particle is the most likely to get through, and therefore the best to use as a benchmark for qualification.
Many manufacturers use HEPA filters to improve the products we use each day. Forward thinking car manufacturers like Tesla use them to provide clean cabin air to passengers. In hospital settings, HEPA filters protect seriously ill patients with lowered immune function from airborne diseases. Elsewhere in hospitals, specialized HEPA masks protect medical personnel from infections. In the home, a HEPA filter helps reduce allergy symptoms, fight dust, and scrub the air of most airborne particulate matter.
What HEPA Filters Can’t Do
HEPA filters provide 99.9999 percent efficiency when removing particulates ranging in size from 1-10 microns, but they will not be able to filter out odor molecules or gasses. In these instances, activated carbon filters are required. Activate carbon often accompanies a HEPA filter.
In some settings, it may be necessary to remove viruses from the air. These are too small to be arrested by a HEPA filter, so an ultraviolet light treatment may be incorporated into the system. For professional and commercial settings there are many specialist additions that can be made to a filter.
How Do HEPA Filters Work?
HEPA filters use a number of different methods to remove unwanted particles from the air. Let’s take a look at a simple HEPA filter, such as you might find inside a vacuum cleaner.
An electric fan or air pump creates a difference in air pressure causing air to move from one side of the filter to the other. First, the air will come into contact with a fine gauze which will act like a sieve and stop the larger particles, like hairs, dust, and
After this sieve-like layer, the air will reach a corrugated filter. Although these filters look like they are made from paper, they are actually made from glass fiber matting. The glass fibers are arranged in a haphazard way, so that air traveling through will not have a direct route, and is forced to curve around the fibers on its journey.
Particles in this section of the filter are not simply ‘sieved’ out. Instead, three different actions come into play which are able to catch particles much smaller than the gaps between the fibers.
These actions are impact, Interception, and diffusion.
Sometimes called inertial separation, impact happens when the air is moving at a high velocity and carrying a particle along with it. Because the particle has gathered inertia and wants to keep moving in a straight line, it will impact any of the glass fibers which are in its way and adhere to them by the force of its impact alone.
Interception works when a particle travels close enough to one of the fibers to get caught on it. In this way, even particles that are smaller than the gaps between the glass fibers can be arrested.
As the air tumbles around inside the glass fiber matting, some of it will be moving relatively slowly. This causes tiny particles to be buffeted around, and often come into contact with the glass fibers which they adhere to, remaining trapped in the filter.
Eventually, the glass fiber matting inside the filter will be unable to capture any more particles from the air, and at this point, a replacement will be needed.
HEPA Filters for Allergies and Asthma
Dust, pollen, spores and pet dander make Asthma and allergies unbearable. A HEPA filter can help to reduce these particles from the air, and studies have shown that they do reduce some symptoms, particularly during the night if placed in bedrooms.
However, you will find the majority of these irritants on surfaces like tables and bookshelves. But, you they also hide in carpeting, rugs, drapes, and soft furnishings. For this reason, it is recommended that the sources of these irritants are removed and the home kept as clean as possible.
Frequent vacuuming, using hard flooring, wrapping bedding in anti-allergy covers, keeping pets away from the bedroom, and frequent washing of soft furnishings are all effective methods of controlling exposure to allergens.
High humidity has also been linked to increased allergy symptoms, so it may be worth considering a dehumidifier if you live in a humid climate, or have moisture problems.
HEPA Filters for the Home
In the home, the main uses of HEPA filters are in air purifiers and vacuum cleaners.
A low-quality vacuum cleaner removes only larger particles of dust and dirt, releasing smaller particles back into the air. A high-quality vacuum cleaner with a HEPA filter can be a great weapon in the fight against allergens.
In order to pull the air through the HEPA filter, a vacuum cleaner needs a more powerful motor. This is why HEPA vacuum cleaners tend to be more expensive, louder, and use more energy than non-HEPA filter models.
As we discussed above, an air purifier alone will not be enough to control allergy symptoms. Some people report great results from them and others don’t see much difference at all in symptoms. For this reason, using an air purifier alongside a vacuum cleaner with a HEPA filtration system will be most effective.
Placing an air purifier in the bedroom may be the most effective choice, as this is usually the room where we spend the most time.
What to look for in a HEPA air purifier.
When looking for an air purifier, make sure that you choose a HEPA filter. These are the only type which have been tested to remove particulate matter. ‘HEPA-like’ and ‘HEPA-style’ are not typically tested, and cannot be guaranteed to be up to standard.
Check what the manufacturer recommends the purifier for – more expensive units will generally remove a wider range of substances from the air. Non-profit allergy organizations, for example, recommend both the Boneco P500 and Bionaire Air Purifier. But, the more expensive Boneco removes a wide range of pollutants, dander, and viruses. While the Bionaire focuses on just dust, smoke, and pollen.
Before you buy a HEPA purifier.
The more expensive models may also be compatible with different types of filter. Thus enabling you to customize the produce to your needs. When buying, remember to check out how long the filters will last. And, how much they will cost to replace to avoid surprises down the line.
Purifiers use a motor to pull air through thier filter(s), so anticipate a bit of noise. Automatic sensors and programmable units will keep running costs down. Check out the size of room the manufacturer recommends. Buying too big may result in higher running costs for no extra benefit.
HEPA filters can create a cleaner and safer environment in your home or workplace. When combined with other features like activated carbon filters they can be part of a system of comprehensive air purification. Which contributes to better health and well-being and improves your quality of life. They’re much safer than ozone generators and are one of the main features you should look for when purchasing a purifier.