What Is the Best Air Purifier Technology for Asthma?

More than 1,000 people are admitted to the hospital each day because of asthma, costing the nation approximately $56 billion each year according to the CDC. Poor air quality and pollutants in both outdoor and indoor air can worsen asthma by potentially triggering asthma attacks  and causing breathing problems. An air purifier is one way to help reduce exposure to asthma-worsening pollutants in indoor air. While preventative environmental measures should be taken to reduce symptoms and risks, using an air purifier is often recommended as part of a comprehensive indoor air quality regimen. Reading reviews is helpful, but understanding the mechanisms at work in different types of air purifiers (e.g. HEPA, carbon, ionizing and, PECO – all explained later) will enable you to make a more informed decision about selecting the best technology to aid in reducing your asthma symptoms.

Choosing the right air purifier for asthma symptoms depends on several factors. We will examine the indoor air pollutants that aggravate asthma and determine what is the best purifier technology for those who suffer from this all-too-common chronic disease.

Indoor air pollutants that aggravate asthma

According to the most recent CDC asthma statistics, 25.2 million people in the U.S suffer from asthma. The World Health Organization (WHO) considers particle pollution, ground-level O3, CO, sulfur oxides, nitrogen oxides and lead (Pb) as the six major air pollutants that are harmful to human health. Because these pollutants enter the body through the airways, air pollution is considered a major environmental risk factor for respiratory diseases like asthma (Lanphear et al., 2011).

Allergic asthma is the most common form, experienced by more than half of all asthma sufferers. This is particularly dangerous as allergens are virtually ubiquitous, varying in type and severity according to seasonal and geographic factors. These pollutants are a major nuisance, so when they trigger an asthmatic response, it’s especially important that care is taken to reduce your exposure to them by any means necessary. It is also important that the correct air purifier is used in these scenarios—an improper purifier may exacerbate the prevalence of certain allergens.

Asthma triggers can come from unexpected places. The aggravation of asthma by allergens usually arises from exposure to or inhalation of pollen, molds, pet dander, dust mite droppings, and even cockroach residue. These particles carry microscopic proteins that can trigger an allergic reaction, which may in turn catalyze an asthma attack. Because allergens are tiny and can be extremely mobile indoors, using both preventative environmental control measures as well as active air filtration and purification is considered best practice.

Allergies aren’t the only thing that can trigger asthma: Dust, secondhand smoke, volatile organic compounds (known as VOCs) and air pollution all contribute to factors triggering asthma attacks. Thus living in dense urban areas or near heavy industrial facilities may increase your likelihood of developing asthma.

Air purifier technology that can help with asthma

According to the EPA, Americans spend 87% of their life indoors. Couple that with the fact that indoor air is estimated to be, on average, 2 to 5 times worse than the air we breathe outside and you have a scenario ripe for asthma triggers.

Fortunately there is technology to modify indoor air quality, and the ability to address the level of exposure to indoor air pollution makes these technologies attractive options for preventing and reducing asthma attacks.

  • HEPA – Air purifiers with high efficiency, particulate air (HEPA) filters are extremely common in homes and offices around the world, and the technology is considered a traditional option for filtering out particles. The HEPA standard is based on filtering out particles as small as 0.3 microns with up to 99.97% efficiency. HEPA filters are often recommended to those with known sensitivities to reduce exposure to indoor allergens such as pet allergens.Studies on HEPA technology alone for asthma sufferers is somewhat mixed, but shows some promise. For example, in a study that examined the effects of  HEPA filters on unscheduled asthma visits and asthma symptoms of children exposed to secondhand smoke (Lanphear et al., 2011), the intervention group (110/220 children) had 42 fewer unscheduled asthma visits than the control group. Another study published in The Journal of Allergy & Clinical Immunology examined HEPA air purifiers as a school based intervention and looked at the effect on asthma symptoms. The authors observed a significant reduction in indoor particulate pollutants and improvement in asthma symptoms and lung function.
  • Carbon Filters – Carbon filters work by using activated carbon to remove airborne chemicals from indoor air. For asthma sufferers, one of the unique benefits of carbon filters is that it chemically removes impurities, rather than just filtering particles out of the air.This is not a new phenomenon by any means as humans have been using charcoal to filter water for hundreds of years. But using carbon filters in air purifier technology is a modern way to benefit from the cleansing abilities of activated carbon. Carbon filters use “adsorption” wherein pollutants stick to the activated carbon bed rather than being absorbed within the structure. Through this process, carbon filtration is designed to remove VOCs from the air you are breathing. Carbon filters can benefit asthma suffers by removing some of these key chemical irritants from the air, but should be paired with something like HEPA technology that actually traps particles.For asthma sufferers, choosing an air purifier that has a carbon filter as well is an option to help minimize exposure to VOCs, chemicals, and odors that are proven lung irritants.
  • PECO – For asthma sufferers, the goal of course is the cleanest air possible. Photo Electrochemical Oxidation (PECO), a newer technology than that of HEPA filters, destroys pollutants rather than just filtering them out. In addition to the physical filtration, a photochemical reaction occurs on a nanocatalyst-coated filter that yields the oxidation of organic matter. This process destroys allergens like mold, pet dander and pollen, as well as VOCs that can aggravate asthma symptoms.

The worst types of air purifiers for asthma

When it comes to aiding in the relief of asthma symptoms, not all air purifier technologies are as effective as the ones listed above. Here are a few you should avoid:

  • Ionizers – An ionizer air purifier works by dispersing charged ions into the air. Ionizers utilize high voltage to add electrons to components of air  Negative ions are supposed to attract the positively charged particles in the air, weighing particles down and making pollutants fall out of the air. When these air purifiers first came into the market, demand was high as they are quiet and do not require filters to work.However, the issue with ionizers for asthma suffers is two-fold: (1) Studies have shown ionizers are not very effective with dust, tobacco smoke, and fungal spores; and (2) ionizers generate ozone, a known asthma irritant that can exacerbate symptoms. With regards to the former, these small particles that are charged by the ionizer, but not collected, can linger in the air exacerbating lung irritation and asthma symptoms. The latter is particularly concerning for asthma sufferers. The EPA has found that ozone, even in small levels, can contribute to asthma complications and the development of chronic lung disease. Studies have also shown that ionizers ineffectively clean the air and often end up just masking the smells and hiding visible particulate matter. All five ionizing air purifiers tested by Consumer Reports failed on tests to remove dust, smoke and pollen from a test chamber.
  • Ozone generators – Some brands still claim that their ozone generating technology is an effective way to combat poor indoor air quality because the ozone will chemically react with indoor pollutants to eliminate the pollutants and create only “safe byproducts.” However, the EPA has concluded that ozone generators can be harmful to your health and worsen chronic respiratory issues and asthma. Being exposed to ozone can trigger severe asthmatic reactions and irritate the lungs. The American Lung Association has warned against the exposure to ozone for those with asthma. In fact, the levels required to remove indoor contaminants have often proven to be well over public health standards. So, while the low levels of ozone in the air purifier might not be extremely detrimental, these purifiers essentially can exacerbate asthma and ineffectively clean the air. For asthma sufferers especially, there is simply no guarantee “safe” level of ozone exposure.

Which type of air purifier is best for asthma?

HEPA with carbon

HEPA filters utilize physical filtration, while activated carbon can trap VOCs and chemicals. Combining these two technologies can be helpful to some extent in reducing levels of allergens and airborne chemicals that can aggravate asthma. Research has shown that asthma sufferers with strong sources of allergens in their home may reduce their symptoms with the use of particle filtration. As far as traditional methods of air purification go, HEPA filters with an added carbon filter is an acceptable option for improving air quality. Filters should be replaced on time to prevent pollutants from aggregating on the filter media.

Our viewpoint

It may seem redundant that we recommend our own technology, but in our view, the PECO technology contained in the Molekule air purifier is the best because it goes beyond simple particle capture to actually destroying many of the pollutants that can worsen asthma.  While traditional particle filtration like HEPA has its benefits, ultimately the pollutants remain on the filter and are not removed permanently.

Asthma and PECO technology have something of a history, too, as Dr. Yogi Goswami, a Molekule founder and key researcher into PECO technology, developed it after his son Dilip continued to suffer from severe asthma, despite having used a number of other technologies.

Other considerations when buying an air purifier for asthma

In addition to the type of filter technology, there are a number of other factors you should bear in mind when selecting an air purifier if you suffer from asthma:

Noise: Some less expensive air purifiers may sacrifice quietness in the motorized fan so it is smart to seek out an air purifier with relatively high CADR and a quiet setting. Sacrificing sleep quality for an air purifier will just be substituting one issue for another.

Power: CADR stands for “Clean Air Delivery Rate,” and it roughly translates to the amount of air the purifier can purify. This isn’t the end-all factor to look for however, so be sure to include other variables when shopping around.

Maintenance: Be honest with yourself about how much time you have to properly maintain your air purifier and choose an option that suits your schedule. Some air purifiers require filter changes every 3 or 6 months, or have combined filters with one change date. Look into companies that offer automatic refill scheduling or packaged deals for the first year to reduce cost. Maintaining your air purifier is a key step in maximizing its efficacy.

Placement and Size: An air purifier placed in the bedroom may be the most effective spot for it to purify the air you breathe while asleep. Checking the dimensions of an air purifier to ensure that it will fit comfortably in a space will make the setup process easier. If the air purifier will be moved from room to room, the weight and portability of the device may also be considerations to keep in mind.


The combination of a rise in asthma sufferers, worsening indoor air, and increased time spent indoors represents a challenging health problem that requires a multi-pronged intervention. While some exposure to allergens and irritants in your daily life is inevitable, doing what you can to modify your indoor air to be the most breathable is an effective step towards reducing asthma symptoms.

An air purifier is not the entire solution, but effective air purification can be a key part of an asthma intervention strategy. With the number of hours spent inside, choosing technology with remarkable purification efficacy can potentially greatly reduce your asthma symptoms. Armed with this knowledge about how different purification technologies work and the potential benefits for asthma sufferers, it is evident that choosing a purifier that uses PECO or HEPA with carbon are both viable options to lessening symptoms.


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