The air we breathe is as much a part of home security as more obvious measures like security cameras and door locks. In this case though, we are not dealing with physical intruders; we are dealing with invisible ones. Allergens, smoke, carbon monoxide, radon, and volatile organic compounds are very real concerns depending on our location and living environment. Read on to determine whether you need an air purifier, the methods of air purification, as well as the best air purification products.

Editor's Recommendations

tl;dr: For the most secure home, you need natural air ventilation (open windows), a general purpose air purifier for allergens and other particulates, a radon detector, and a carbon monoxide detector.

GermGuardian AC4825

  • HEPA filter
  • Activated carbon (charcoal) filter
  • Ultraviolet light (UV-C) with Titanium Dioxide
  • No ozone emissions
  • Proprietary filter needs replacement every 6-8 months
  • Can be loud due to fan

Table of Contents

Reasons To Get An Air Purifier

We don't need specific reasons to get an air purifier - sometimes there is a psychological benefit to thinking the air we are breathing is cleaner and fresher. For those needing concrete reasons, the following are major reasons to get an air purifier (or related air products).

Allergens, Allergies, and Asthma

Definition An allergen is a type of antigen that produces an abnormally vigorous immune response (an allergy) in which the immune system fights off a perceived threat that would otherwise be harmless to the body. Allergens can be found in a variety of sources, such as dust mite excretion, pollen, pet dander or even royal jelly.1

If you or someone in your home suffers from allergies, or even just happen to sneeze a little too often, then you should get an air purifier. Allergies are not just an inconvenience; they can trigger severe responses requiring hospitalization. Air purifiers will remove dust, pollen, pet dander, mold spores, and dust mite feces, and should be used in conjunction with thorough and consistent vacuum cleaning.

Definition Asthma is a condition in which your airways narrow and swell and produce extra mucus. This can make breathing difficult and trigger coughing, wheezing and shortness of breath. Exposure to various irritants and substances that trigger allergies (allergens) can trigger signs and symptoms of asthma.2

Like allergies in general, asthma can be triggered through a variety of allergens as well as pollutants like smoke (see the next section). Internal air quality for those with asthma is just as important as food and physical activity.

» Jump to product recommendations for Allergens, Allergies, and Asthma

Secondhand Smoke

Definition Secondhand smoke is smoke from burning tobacco products, such as cigarettes, cigars, or pipes. Secondhand smoke also is smoke that has been exhaled, or breathed out, by the person smoking. Tobacco smoke contains more than 7,000 chemicals, including hundreds that are toxic and about 70 that can cause cancer.3

The best and most obvious way to prevent secondhand smoke pollution is to, well, stop smoking! If that is not an option however, then using HEPA filters, ionizers, and other mechanical air filters can reduce both the smell and detrimental health effects. Note that air purifiers are not a 100% effective solution.4 For dealing with damage from previous smokers or fires, look into ozone generator solutions (be careful with this one).

» Jump to product recommendations for Secondhand Smoke

Volatile Organic Compounds (VOCs)

Definition Volatile organic compounds (VOCs) are emitted as gases from certain solids or liquids. Organic chemicals are widely used as ingredients in household products [like] Paints, varnishes;and wax... [and] many cleaning, disinfecting, cosmetic, degreasing and hobby products. 7

Due to the nature of their use, popular household products like paints, cleansers, and dry-cleaning all contribute to elevated indoor levels of VOCs. Symptoms range from flu-like symptoms to organ damage and even cancer. The best ways to mitigate these effects are limiting exposure and proper ventilation. Air purifiers that use activated carbon and charcoal can also reduce VOC presence.

» Jump to product recommendations for VOCs

Carbon Monoxide

Definition Carbon monoxide, or “CO,” is an odorless, colorless gas that can kill you. CO is found in fumes produced any time you burn fuel in cars or trucks, small engines, stoves, lanterns, grills, fireplaces, gas ranges, or furnaces. CO can build up indoors and poison people and animals who breathe it.5

If you experience unexplained headaches, dizziness, weakness, upset stomach, vomiting, chest pain, or general flu-like symptoms, immediately check your CO levels. For prevention, be smart about not burning things indoors, and have proper ventilation for your car garage and rooms connected to your heating system. CO poisoning can strike anyone anywhere, so monitoring is as essential as proper ventilation.

» Jump to product recommendations for Carbon Monoxide


Definition Radon is a gas that you cannot smell, taste or see. Radon forms naturally when uranium, thorium, or radium, radioactive metals, breaks down in rocks, soil and groundwater. People can be exposed to radon primarily from breathing radon in air that comes through cracks and gaps in buildings and homes. Because radon comes naturally from the earth, people are always exposed to it. When you breathe in radon, radioactive particles from radon gas can get trapped in your lungs. Over time, these radioactive particles increase the risk of lung cancer. Radon is the second leading cause of lung cancer after cigarette smoking.6

We'll just let the above definition speak for itself. Radon can have a serious long-term effect on your and your family's health if left untreated. Levels of radon can vary greatly by geography and season. If you have a basement or other home area close to the Earth or with poor ventilation, it is very highly encouraged to check for radon. The EPA recommends checking every 2 years and especially if you are buying or selling a house.

» Jump to product recommendations for Radon

Methods of Air Purification

Natural Ventilation

Definition Natural ventilation is the process of supplying air to and removing air from an indoor space without using mechanical systems. It refers to the flow of external air to an indoor space as a result of pressure differences arising from natural forces.7

The best form of air purification is by nature itself. Our windows and doorways to the outdoor world can drive fresh air into our homes through wind direction and temperature differences, in any latitude and longitude. Depending on the environment of where we live, though, using the immediate outdoor air may not be a good idea (and may sometimes be itself the impetus for getting an indoor air purifier; see air pollution). Cold outdoor weather with indoor heating also often prevents us from comfortably keeping windows open. Use your best judgment, but generally your first choice for air purification should always be natural ventilation wherever possible.

High-Efficiency Particulate Arrestance (HEPA) Filters

Definition The HEPA filter must satisfy certain standards of efficiency such as those set by the United States Department of Energy (DOE). To qualify as HEPA by US government standards, an air filter must remove (from the air that passes through) 99.97% of particles that have a size of 0.3 µm.8

HEPA filters trap small pollutants and particulates in air passing through the filter using a mat of fibres. In particular, allergens like dust and pollen are very effectively captured, making HEPA a necessary requirement for any solutions dealing with allergies and asthma. Because of the popularity of HEPA, some products may claim to be "HEPA-type" or "HEPA-like", which do not meet the DOE requirements. Many vacuum cleaners now also boast HEPA filters (great for keeping the carpets allergen-free).

Activated Carbon & Charcoal Purifiers

Definition Activated carbon is a form of carbon processed to have small, low-volume pores that increase the surface area available for adsorption or chemical reactions. Filters with activated carbon are usually used in compressed air and gas purification to remove oil vapors, odor, and other hydrocarbons from the air.

Aside from HEPA, activated carbon is the most common and effective type of air purification. Activated carbon uses pores to absorb smoke particulates, odors, and VOCs, something HEPA cannot do - it's not a coincidence that we see the HEPA + Activated Carbon combination in many modern air purifiers.

Air Ionizers

Definition An air ioniser is a device that uses high voltage to ionise (electrically charge) air molecules. Airborne particles are attracted to the electrode in an effect similar to static electricity. Air ionisers have been used to eliminate the occurrence of air-borne bacterial infections... [as well as] inactivate viruses including influenza.9

Air ionizers have recently become popular in air purifiers due to epidemics like the SARS virus. Our greatest concern however with air ionization (and a related form called electrostatic precipitation) is that they produce trace amounts of ozone - usually within industrial safety standards, but variation in manufacturing and individual reactions to ozone makes us cautious towards recommending this purification method.


Definition Ultraviolet germicidal irradiation (UVGI) is a disinfection method that uses short-wavelength ultraviolet (UV-C) light to kill or inactivate microorganisms. UVGI can be used to disinfect air with prolonged exposure.10

Ultraviolet irradiation requires time for sufficient exposure to kill germs like bacteria, viruses, and molds. For this reason typical air purification systems with moving air are not effective with UVGI (don't be sold by the hype!). Ultraviolet is useful when used in areas that are prone to natural moisture, as they can prevent bacteria from accumulating.

Product Recommendations

For Allergens, Secondhand Smoke, and VOCs

Recommended GermGuardian AC4825

Alright guys, this is the real deal. The GermGaurdian air purifiers are consistently Amazon top 10 best sellers in both HEPA Air Purifiers and Charcoal Air Purifiers categories, as well as in Overall Home Air Purifiers. The GermGuardian models use a multi-layered approach to purification: activated charcoal filter, then HEPA, and combined with ultraviolet-activated Titanium Dioxide (more info on this method, may not be very effective; see our note on UV-C above). The combination of all 3 methods means you only need one purifier to deal with allergens, secondhand smoke, and VOCs. The AC4825 is 22" and perfect for medium-sized rooms.

  • HEPA filter
  • Activated carbon (charcoal) filter
  • Ultraviolet light (UV-C) with Titanium Dioxide
  • No ozone emissions
  • Proprietary filter needs replacement every 6-8 months
  • Can be loud due to fan

Official Video

Want to go bigger? GermGuardian offers an older brother 28" model called the GermGuardian AC5250 for those with larger rooms and homes.

Want to go smaller? GermGuardian offers a nice-looking little brother 11" model called the GermGuardian AC4100, perfect for those with smaller spaces, like a bedroom or studio apartment. The features are all the same.

GermGuardian AC4100

Coway Mighty Air Purifier

For a stronger punch, consider the Coway Mighty Air. The main difference between this air purifier and our recommended purifier (GermGuardian) is the addition of an ionizer - we talked about the inherent risks of using an ionizer (they produce ozone), so make sure you have a good reason to get a stronger air purifier. The other big advantage of the Coway is the automatic mode: sensors in the machine monitor air quality levels and adjust the fan level based on what it sees. Great as a set-and-forget.

  • HEPA filter
  • Activated carbon (charcoal) filter
  • Air ionizer
  • Auto mode adjusts based on sensors
  • Stylish form factor
  • Air ionizer may produce trace amounts of ozone
  • Proprietary filter needs replacement every year
  • Can be loud due to fan

For Carbon Monoxide

Detection (and subsequent professional work to fix the root cause) is the best way to combat potential carbon monoxide poisoning. The recommendation is to have a carbon monoxide detector in every floor of the house, as well as any further enclosed area with poorer ventilation.

Recommended Kidde Nighthawk

The Kidde brand is the best in the fire and smoke detection market. This product, the Nighthawk, is the highest rated no-fuss carbon monoxide detector and alarm from Amazon. We like that it is both plug-in and battery for continuous use, something most other similar products do not have.

Kidde Battery-Operated

The Kidde Battery-Operated detector and alarm is similar to the Nighthawk but is smaller and only battery-operated, making it more portable. Functionality is nearly identical.

For Radon

Like carbon monoxide, detection and professional work is the best route for radon poisoning.

Recommended National Radon Program Services Test Kit

The EPA recommends the National Radon Program Services discounted test kit offered through Kansas State University. Both short-term ($15) and long-term ($25) kits are offered with free analysis, with the latter being much more accurate.

First Alert RD1

If for some reason you cannot use the National Radon Program Service, the First Alert RD1 is a great alternative. It is EPA-listed, inexpensive, and easy to use, with no hidden fees for analysis.


We take the "invisible" security of home air quality just as seriously as physical security. For overall air quality, natural ventilation can't be beat, and an additional general-purpose air purifier can help a lot. Carbon monoxide and radon detection are also necessities, especially if you are considering buying or selling a home. Breathe deep and stay lazy, friends!

Thoughts or questions? Let us hear them in the comments below!