Air Purifier Buying Guide

Research has shown that indoor air quality is often more polluted than the air outside our homes. The Environmental Protection Agency recommends using an air cleaning system to help maintain healthy indoor air. However, trying to figure out which unit is best for you can be challenging. The following information will help guide you in choosing the right air purifier for your environment.

For easy accessibility to the topics in this article, use our topic list provided below:

About Air Purifiers
Filters: Types and Purposes
Addressing Specific Needs: Allergies, Asthma, Smoke
Cost and Considerations
Maintenance
Size and Efficiency
Calculating CFM (Cubic Feet per Minute)
Noise Level
Special Features

About Air Purifiers

Standard air purifiers, also known as air cleaners, are designed to remove pollutants and particles such as dust, pollen, pet dander, chemicals, and odors from the air. In general, these units work in one of two ways: (1) by collecting particles in physical material filters or (2) by creating an ionic (static) charge to attract particles onto a collection plate. Some machines are designed to use a combination of these two methods.

There are two basic types of air purifiers to choose from: mechanical filter systems (also known as traditional filter purifiers) and electrostatic systems.

Traditional Filter Purifiers: Air purifiers with traditional filters work by pulling indoor air inside the unit and pushing it through the filter by way of an electric fan. When inside the unit, the air is cleaned of pollutants and particles as it passes through the filter, which traps these contaminants, before it is pushed back out into the room.
Electrostatic Cell/Plate Air Purifiers: Electrostatic air cleaners work by pulling air into the unit and passing it over an electrostatic field that traps the particles onto metal plates. The plates will become dirty as more and more air pollutants are collected on top. Once the plates become covered with dirt, their efficiency starts to diminish. Therefore, it is crucial for the plates to be cleaned regularly in order for them to work effectively.

When choosing a unit, first choose a model with a filtration system designed for your specific problem. Whatever results you are trying to achieve, whether it's for general particle fitration, for smoke and odor removal or to help reduce multiple chemical sensitivities, there is an air purifier out there that can help.

Filters: Types and Purposes

All air purifiers use some type of filter to assist in cleaning the air. There are several types of filters, and each have a specific purpose.

HEPA Filters: High Efficiency Particulate Air (HEPA) filters remove 99.97%-99.99% of particles that are 0.3 microns and larger from the air, which makes them ideal for removing allergen triggers such as pet dander, dust mite residue, and pollen. Some air purifiers are certified to work even better than HEPA; these are called hyperHEPA units. These units are especially beneficial for individuals who suffer from allergy sensitivities and respiratory conditions such as asthma.

Carbon Filters: Carbon filters are used to remove odors and chemicals from the air. These filters use what is known as "activated carbon," which means that the pores of the carbon have been opened so that they can absorb substances (pollutants). Absorption occurs when pollutant chemicals are attracted to the activated carbon. (Carbon is able to absorb a range of chemicals.) The open pores of the carbon fill up with the odors and gases. Once all the holes are filled, the carbon filter is no longer active and needs to be replaced. Carbon is most often used to absorb:
- Smoke (from cigarettes and fireplaces)
- Formaldehyde and other volatile organic compounds (from furniture, carpet glues, paints, plastics, new building materials, etc.)
- Odors (pet, kitchen, etc.)
Pre-filters: Pre-filters help trap large particles before they reach the internal components of the air cleaner, specifically, the HEPA filter (or a similar main filter) or the electrostatic metal plates. Having this pre-filter is a great benefit, as it helps to extend the interval time between cleanings or filter changes and maintains the unit's functionality and efficiency longer.

Addressing Specific Needs: Allergies, Asthma, Smoke, and Chemical Sensitivity

Air purifiers come in a range of specialties. Based on your specific needs, you can pick one that will make the most impact in combatting your indoor air pollutants, whether it's smoke, pet dander, pollen, or chemicals. Look for a purifier with a true HEPA filter for the best particle filtration. If you have multiple needs to address, you may want an air purifier with a carbon filter as well. Air purifiers can reduce the severity of symptoms associated with the following conditions:

Seasonal Allergies: Air cleaners are a great benefit for those individuals who suffer from seasonal allergies. Units that feature HEPA filter technology trap both small and large particles so that you are not breathing them in. All the allergy triggers that cause the itchy, water eyes, sneezing, and coughing are out of your air and out of your way. Imagine being able to enter an oasis of clean, healthy air every time you walk through your door. For allergy sufferers, air cleaners create just that.

Bottom line: For this need, choose a unit with a HEPA filter or consider a high-quality electrostatic unit. Check out our article on air purifiers for allergies for more information.

Pet Allergies: If you have a pet or multiple pets and you or someone in your home is allergic to them, then an air purifier will help the situation. Most people are allergic to the actual dander from cats and dogs. Dander, which is shed skin cells from animals, is very tiny and can remain in the air for a long time. It also tends to go where your pet goes and stays after your pet has left that area. Air purifiers are able to clean these particles from the air, trapping the dander in the filter. These units also help reduce fur particles that float throughout the air. As the air is exchanged (cleaned), it will pull airborne pet hair into the unit where it will become trapped by the pre-filter.

Getting an air cleaner with carbon will also help with pet odors. The carbon will absorb those undesirable pet smells, leaving a home with clean, fresh, and healthy air.

Bottom line: For this need, choose a unit with a HEPA filter or consider a high-quality electrostatic unit. If you want to address pet odors, choose a unit with carbon filtration as well. Check out our page on air purifiers for allergies.
Dust and Dust Mites: Dust mites are tiny cream-colored organisms that live off organic material such as dead skin flakes or dust. Our homes are the perfect environment for dust mites to live in and breed. Because of their tiny size and multiple legs, dust mites can move easily through the air on the slightest of air currents, such as those created when you are changing the sheets or sweeping. Not only are dust mites less than pleasant to think about, they can also cause respiratory problems. Air purifiers help to eliminate these little parasites by pulling them out of the air and trapping them in the filter, leaving behind healthier, cleaner air.

Bottom line: For this need, choose a unit with a HEPA filter or consider a high-quality electrostatic unit. Check out our page on air purifiers for clean indoor air.

Asthma: Air cleaners can positively impact your indoor environment if you suffer from asthma. Asthma triggers saturate indoor air and an air purifier can help diminish them. Thousands of people have breathed in the difference an air purifier can make in their lives. There are many units on the market today designed to target asthma triggers. They will give you peace of mind, knowing that you are doing all you can to stop asthma attacks before they start.

Bottom line: For this need, choose a unit with a HEPA filter, to address the particles that can trigger an attack, and carbon filtration, to address things like perfume odors and other indoor chemical pollutants that can aggravate asthma conditions. Check out our asthma air purifiers.

Smoke: Smoke from your fireplace, cooking, or tobacco can cause a number of issues in your indoor environment. Getting rid of the smoke and counteracting the smell is an important issue for many people. Air cleaners can greatly affect smoke in your indoor environment. If this is your number one concern, then choose a unit that is specifically designed to handle this problem. There are filter units with carbon as well as electrostatic units that can handle this smoky problem with ease.

Bottom line: For this need, choose a unit with a carbon filter or a high-quality electrostatic unit. Check out our smoke air purifiers.

Chemical sensitivities: Chemical sensitivity can be divided in two categories.

First, some individuals are sensitive to one chemical or to a number of chemicals present in their home, and they need an air purifier to address this specific issue. A high-quality unit with ample carbon and effective filtration will be able to solve this problem easily.

The second type of chemically sensitive person is one who is highly reactive to most of the chemicals they come in contact with. In general, these include the glues, filters, and plastic material found in many air purifiers. If you feel that you fall into the this category, don't despair. There are great units on the market that do not off-gas. When you are ready to purchase a unit, just remember that you will want to take special care in choosing your air purifier, as many units claim to cause no off-gas, but still do. Individuals with severe chemical sensitivities should consult our page devoted to air purifiers that do not off-gas and that are designed for individuals with these specific needs. Sylvane offers a free consultation to assist you in your buying process. Allow us to find a unit that will suit your specific needs.

Bottom line: For this need, choose a specially designed unit with carbon filtration. Check out our chemical sensitivity air purifier page.

The key to picking the right air cleaner for your indoor space lies in knowing what problems you want the unit to address.

Some air purifiers can be customized to suit a variety of needs. For example, customer-specific carbon-profiling can help make sure that you get the right activated carbon for your chemical sensitivity. If you feel you need a customized unit, please contact us for a consultation at (800) 934-9194.

Cost and Considerations

The price of an air cleaner can range from around $200 to more than $1,000. Deciding whether to choose the low-end or high-end model can be confusing. Though air purifiers generally operate in the same way (air is pulled into the unit, cleaned, and then blown out) the logistics of how this is accomplished (the internal design of the unit and the quality and quantity of clean air coming out of the unit) is different for every unit.

You don't have to be an air purifier expert to figure out which unit is best for your needs, you simply need to determine what your needs are. For example, a customer might ask the following questions to get the process started:

Why am I getting this unit? Am I looking to reduce allergies, asthma, chemical sensitivities, or odors?
Is this unit for a single room? Or am I trying to clean all the air in my house?
How big is my space (estimated square footage, considering high ceilings)?
How long do I expect the unit to last?
What is my budget?
How much does it cost to maintain and replace filters?
Do I want a model with electrostatic plates that I have to clean frequently, or do I want a unit that only requires replacing a filter less frequently?
Do I want special features such as a change filter indicator light or a remote control, etc.?

Answering the above questions is a useful, time-saving method to help you decide what type of unit you need in order to address your specific indoor air issues. Additionally, Sylvane offers product experts who can guide you through the buying process, contact us today at (800) 934-9194 for a free consultation.

Maintenance

Maintaining an air purifier is an important part of keeping the unit working effectively, and there is a certain amount of cost and effort involved. Certainly, air purifiers work for a time as a "turn it on and forget it" appliance. However, to get the most out of your investment, you must change the filters on time or as needed, and if you choose an electrostatic unit, you have to be committed to cleaning the metal plates regularly. For more information, please see our article on Air Purifier Maintenance.

The cost of filters varies by unit and by type of filter, so it is important to check the price point on filters and the frequency of filter changes before you decide to purchase a particular unit. Also, consider the environment in which you want the unit to function. For example, if you smoke in your home and you want a unit that will help filter the smoke and rid the air of smoke odors, you will want a unit with an ample amount of carbon filtration or an electrostatic unit. Then, the choice will be between the physical cleaning of electrostatic plates (usually done once a week) and the cost of replacing carbon filters as they become saturated.

Size and Efficiency

Air purifiers work best in the room they are placed in, and they lose effectiveness the further you move away from that room. Therefore, single-room units cannot effectively clean the air in your entire house, since only the air that gets sucked into the unit gets cleaned. However, multiple units or a combination of single-room units with a whole-house unit is the best choice for complete home air purification.

When choosing what size unit to buy, you must carefully consider the size of the area you want to clean. There is a specific formula for calculating how many air exchanges per hour any unit will perform. Using this formula is a great way to figure out whether the unit you are considering will perform to your expectations (for more information on this formula, please see the section entitled CFM in this article). However, any calculation of air exchanges per hour (the ideal exchange rate is between 5-6 exchanges per hour) is only a basis or foundation for helping you consider how a unit will perform in your home. CFM does not take into consideration the design of your home; which affects the air flow from room to room; ceiling heights; the amount of furniture in your home the air must circulate around; the insulation of your rooms; and the amount of indoor air pollutants, such as pet and dust odors, that the air purifier will be addressing.

Another consideration when it comes to efficiency is the air purifier fan. A general rule of thumb is that the larger and stronger the fan, the more air the unit can clean and the faster it can clean it. A unit with multiple fan speeds will allow you to customize your air cleaner to better suit your needs.

Also, remember an air purifier can markedly improve the quality of your indoor air, but it cannot eliminate pollutants completely. It won't suck all the dust from your hard surfaces or prevent pollen from entering your house. But it will help you to breathe easier, reduce your allergy symptoms, and give you peace of mind in that your indoor air contaminants are minimized.

Calculating CFM (Cubic Feet Per Minute)

A good way to begin your search for an air purifier is figure out how to get the ideal air exchange you want in any given space. An ideal air exchange rate refers to how many times the air is changed (or cleaned) in one hour. Ideally, this number should be between 5 and 6 times per hour. Many elements can affect CFM: fan speeds, insulation, air flow in the room, furniture in the room, and the amount of pollutants in the air. With those "extra" considerations aside, this is the formula for calculating an air purifier's CFM exchange:

CFM = Number of Cubic Feet in Your Room (Length x Width x Height)
Required Number of Air Exchanges Per Hour

See the bullets below for a step-by-step example of the formula above.

Required (ideal minimum) number of air exchanges per hour = 5
Room size = 18 ft. x 24 ft. (length x width); multiply this number by the ceiling height of the room. For this example, it is 8 ft. This gives you a total of 3,456 cubic feet.

Plug your numbers into the above formula like this:

CFM=	18 ft x 24 ft x 8 ft
	5 (air exchanges)

CFM =	3456
	5

CFM =	691.2

You will need an air purifier that can produce at least 691 CFM.

Noise Level

Some people call it noise, others say it's sound, and some refer to it as "background noise" or "white noise." Whatever its' title, it does exist. You cannot find a silent air purifier because these units work by physically moving air through by way of a motorized fan. So, even though air purifiers are not silent, the amount of sound they produce varies considerably. Many factors contribute to the range and level at which the sound becomes softer or louder. Consider the following elements when deciding what type of unit will best suit your indoor (and noise) preferences:

Will the unit be in my bedroom? This is the most common area in which air purifiers are placed. However, it's also the number one area where people find high levels of sound to be the most intrusive. If you are a person who cannot tolerate any noise while falling asleep, having an air purifier with a timer that can be set to come on after you are deeply asleep might be the ideal solution. On the flip side, many people enjoy the "white noise" created by an air purifier, as it can help create a calming effect in the room. Either way, it is important to understand that some level of noise will come from these units, and it's just a matter of finding the level of sound you are comfortable with, or purchasing a unit with special features, such as a timer or fan speeds of varying noise levels, that will help minimize the sound.

What sound level is the unit comparable to? Many units list the decibel (dB) rating of the system for each fan speed. You can compare these ratings to the sounds made by other indoor appliances, such as the noise emitted by a normal box fan or the "hum" sound that a refrigerator makes. This will give you a point of reference when making your choice.
Be careful to remember that noise levels are different to each individual. Even decibel results can sometimes be misleading since many things can affect the sound level, such as position of the unit, carpeting, furniture, distance from the unit while it is running, fan speed, etc.

Special Features

Many air purifiers on the market offer a variety of special features that can greatly enhance your air-cleaning experience. These features add convenience to your life and provide additional options that allow you to optimize your air purifier to best suit your needs. Some of the special features to consider when shopping for your air cleaner are:

Casters for ease of mobility
Remote control
Digital controls
Multiple fan speeds
Handles
Ease of filter change
Integrated timer
Filter-change indicator light