Air Purifier Buying Guide |
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Quality air purifiers have never been more important for good health. The tight seals that make your home comfortable and energy efficient also trap indoor air pollution. From cooking fumes and cleaning vapors to dust and pet dander, there is a wide variety of vapors and particles that pollute indoor air. Statistics from the Center for Disease Control (CDC) and Environmental Protection Agency (EPA) have shown that the air inside your home can be five to ten times dirtier than the air outside, and more importantly, Americans spend an average of 90% of their lives indoors.So you decided you want to do something about this and begin searching. Shopping for the right air purifier can be confusing and frustrating. Some air purifiers on the market actually pollute the air with harmful levels of ozone, a powerful lung irritant that can be especially dangerous to asthma sufferers. Many are marketed as inexpensive and use language that makes the air purifier appear to be something that it is not. Others will provide filtration or air flow rates rates based on theoretical results, not actual testing or usage. Others still can simply confuse you with the sheer number of options, sizes and prices available, and leave you feeling just as overwhelmed as when you first began your search. No matter the brand, price or style of air purifier you are searching for, there are key things to look for with any air purifier. To help you learn about air purifiers and find a safe, effective unit that is right for your needs, we created this air purifier buying guide. | |||||||||||||||||||||||||
Common Household Air Pollutants |
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Different air purifiers target different pollutants, so first it is important to identify which pollutants you want to eliminate from your home before you buy an air purifier.
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Air Purifier Filter Types |
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Because different air purifier technologies have different strengths and weaknesses, many modern air purifiers combine two or more filter or media types in the same unit. For example, our #1-selling Austin Air Healthmate utilizes a HEPA filter along with a thick bed of activated carbon to help eliminate dust, pollen, and dander as well as things like smoke, odors, and chemical vapors. Regardless of the filter media used, always look for some mention of a “sealed system” or similar terminology. The best filter in the world is literally worthless if the unit leaks air and allows purified and dirty air to mix. With that being said, let’s take a closer look at the different types of filters: | |||||||||||||||||||||||||
Air Purifiers offering HEPA filtration: Austin Air, Blueair, Aeris Health Air Purifiers, Honeywell, Air Pura, Germ Guardian, and Whirlpool.
** Why 0.3 microns? 0.3 microns is what has been determined to be the Most Penetrating Particle size. In terms of a HEPA filter, 0.3 microns is the Most Penetrating Particle size because it penetrates or passes through HEPA filter media the easiest – it’s the hardest particle to trap. HEPA filters trap particles by one or a combination of three mechanisms, impaction, interception, and diffusion. Particles that are 0.4 microns or larger are often snared by impaction or interception while diffusion is what traps most particles 0.1 microns or smaller. This leaves a gap, right around the 0.3 microns, where filtration becomes extremely difficult, and thus, the weak point of the filtration spectrum. Much like the weakest link of a chain, a HEPA filter is only as good as its weakest point of filtration, and that is 0.3 microns. |
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Air Purifiers for Allergy Relief |
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Air purifiers help allergy sufferers by removing allergens in a specific environment, whether that is your home, office, or dorm. In the home, we strongly recommend starting in the bedroom since people tend to spend more time in this room than any other in their house. Starting in the bedroom allows you to create an allergy friendly environment for yourself, and a space where you can get a good night’s rest. Air purifiers only remove airborne contaminants and allergens. Particles that are heavier will precipitate out of the air and settle on furniture and flooring, which means to make your bedroom truly allergy friendly, an air purifier is only a good first step. Now that you know where to start, what other things are there to consider before you buy? | |||||||||||||||||||||||||
Air Purifier Air Exchanges |
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Most quality air purifiers operate efficiently and quietly in a one room environment. To be effective, an air purifier must have a motor and fan powerful enough to properly circulate air throughout the space. Once the air is pulled into the unit, it is filtered through various types of filter media, and clean air is released back into the one room environment to start the cycle all over again. The amount of time it takes an air purifier to cycle through all of the air in a room is referred to as an “air exchange.”
The more air exchanges per hour (ACH), the better air quality in the room. The number of air exchanges is determined by two things: the cubic feet (volume) of a room and the cubic foot per minute (CFM) output of the air purifier. All air purifier manufacturers list airflow ratings (in CFM) for each fan setting at which their machine operates. Ideally, you want to set a goal of 4 to 6 air exchanges per hour. There is no such thing as overkill when talking about air exchanges. |
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Proper Placement of an Air Purifier |
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As a general rule, it is more difficult to filter the air in a large and open space, and this is mainly due to inadequate air circulation. Large living rooms and family areas, especially those with abnormally high ceilings, present a challenge to effective air filtration. Our rule with larger rooms is to attempt to direct the purified air exhaust from the air purifier to the vicinity of the rooms inhabitants. Many of the machines we sell have directional outflow registers. This allows the user to dictate where the clean air cycle begins and ends. Inside a room, be sure to keep adequate space around the air purifier, typically 18″ or more. Most units intake air from multiple sides, and restricting this by placing the air purifier against a wall or piece of furniture will reduce efficiency.
In the bedroom, place the unit 6-10 feet from the headboard of the bed with the directional registers pointing at the bed. This is often far enough away to avoid feeling a draft but close enough that cleaned air is reaching you. Most air purifier manufacturers implement a bottom to top airflow–meaning the air is pulled into the machine at the bottom and released towards the top. Years ago when Honeywell made some of the only home air purifiers, and their models pulled in from the top and exhausted downwards towards the floor. This system runs counter to the conventional wisdom of working with gravity to create air circulation. Fortunately their designs have changed for the better and other manufacturers have followed and further innovated with better air flow circulation in mind. |
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Air Purifiers Performance and Limitations |
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Air purifiers will not perform miracles, but they can go a long way in reducing allergens and irritants in the home, while improving indoor air quality. The effectiveness of an air purifier varies along several factors. You specific sensitivity or the severity of your reaction to the offending allergen, the source and concentration of these irritants in the home, and the type of air purifier being used.
One of the easiest particulates to filter from the air is dust. Dust is abundant and omnipresent, but these particles tend to range from visible (which are generally filtered by your body before they can reach the lungs) to 10 microns (effectively filtered by a HEPA air purifier). Some of the hardest airborne particulates to filter are cat dander and toxic chemicals. Cat dander is extremely small, and can stay aloft quite some time. In fact it is one of the smallest, common indoor allergens. This type of dander is also “sticky”. Once it does land, it adheres easily to fabrics, walls, and flooring. This means if you’ve just moved into a home that used to have a cat, to you, it may still feel as if the cat is there! For those who are actually allergic to their beloved pet, things can be even more difficult. While there are a variety of things you can do to mitigate the allergen, using a HEPA air purifier in the bedroom and keeping the cat out of that room can go a long ways to keeping your allergies at bay. Another factor that can impact air purifier performance and efficiency is whether or not it has a sealed system. A sealed system generally refers to a series of seals or gaskets that ensures that once air enters the air purifier it does not leave the machine until it has passed through the filters. For those coping with moderate to severe allergies, a sealed system machine is one that should strongly be considered. One of the biggest performance problems isn’t actually a problem with the performance of the air purifier. It’s often the result of a mismatch between what type of filtration is needed and what type of filtration is being used. Odors, perfumes, smoke, and chemical vapors will largely pass right through a HEPA air purifier, and even units with a carbon prefilter often contain so little carbon that they cannot adequately filter these pollutants. Large activated carbon filters are often the best way to solve this problem. This highly adsorptive substance has an extremely large surface area to size ratio, and it is this characteristic, combined with chemical properties of carbon that make it ideal for trapping odors, smoke and vapor pollution. For more specific filtration of VOCs consider carbon that has been blended with other materials, like potassium permanganate, potassium iodide, alumina and zeolite. These substances can broaden the chemical filtration range of carbon or oxidize VOCs. Paring the right filter media for your needs is kep to getting the performance you want from your air purifier. |
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Air Purifier Fans, Motors, and Usage |
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Should you leave my air purifier on all the time? The answer is an emphatic YES! (Unless there is an unusual circumstance like you are leaving on a 3 month vacation). Air purifier motors are generally quiet on low to medium speeds, very energy efficient, do not output much noticeable warmth, and easily maintain a constant RPM. The fact remains, an air purifier cannot clean the air if it is not turned on. In fact, we recommend turning your air purifier on its highest setting when you are away. The highest fan speed setting is usually too loud to tolerate when you are in the room, which is why we often suggest running it on the highest setting when you are absent from the room. Upon returning, turn the fan speed down to a more comfortable level. As a final note, every HEPA air purifier is likely to be “loud” when used on its highest setting. Any unit worth the money you spent on it must be able to properly circulate air throughout the room, and this relies on a fan. | |||||||||||||||||||||||||
Air Purifiers Benefits vs. Side Effects |
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Some of the many benefits of using an air purifier in your home or office include: breathing less contaminated air, keeping your allergen load below its reactionary threshold, sleeping and breathing better, and living healthier without additional pharmaceuticals or a radical lifestyle change. The side effects of using an air purifier are very small: energy cost (average to the cost to use a 60w light bulb) and white noise. Actually, most people unknowingly benefit from the white noise from air purifiers. White noise drowns out distracting background noises that can interrupt sleep, and for many, white noise can actually be relaxing. For these reasons, white noise is actually used widely in sleep centers throughout the country. | |||||||||||||||||||||||||
Wash or Replace Pre-Filters? |
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A debated subject in our company is whether you should wash or replace pre-filter media? It is often a personal decision. Pre-filters capture the large particles and often need to be replaced more frequently. Some people do not mind ordering a few extra filters and simply throwing away the old filters when it is time to replace. Other people have no problem removing the old pre-filter, vacuuming it or rinsing it with water, and allowing it to dry thoroughly, and repeating this process a couple times before actually replacing the filter. With activated carbon prefilters, you can use them beyond the recommended 3-6 months, but generally after this time period, they have adsorbed as many odor or smoke molecules as they can hold with their limited amount of carbon. So while cleaning them will extend their large particle trapping capabilities, most smoke or odor adsorption will have ceased. There is some flexibility in this, so in most cases, cleaning and reusing prefilters or simply replacing them boils down to a personal decision. | |||||||||||||||||||||||||
Beware of Scams and False Advertising |
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As the case with many industries, there are good guys, bad guys, and some in between. In the past, there was a very good example of the problems within this industry. According to the EPA as well as Consumer Reports, many manufacturers were falsely advertising that ozone cleaners were air cleaners. This was, and is, false. Resellers and dealers go with what information is provided to them and at the time, there was little information out about how this type of machine could negatively effect health. Even after more information came to light, many continued to manufacture and electrostatic precipitators are rarely seen for residential use.
More recently, many people will recall the Ionic Breeze by Sharper Image. This air purifier made amazing claims, required no filters, and used no fans. One class action lawsuit later, and we all discovered that not only did this air purifier not work, but it was actually producing ozone. Buyer beware, if it sounds too good to be true, then it probably is. Again, air purifiers will not perform miracles, and there is never a short of dubious people out there who continually try to make a quick buck from duping another. |
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Summary of Factors to Consider Before Buying an Air Purifier |
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