Skip to main content

For many people, the health risks posed by indoor air quality can often be much higher than outdoor air. Animal dander, pollen, mold, dust mites, and fumes released by cooking, burning fuel, or cleaning products can all negatively impact your indoor air.

One way you can improve your indoor air quality is with a CERTIFIED asthma & allergy friendly® air cleaner. Many air cleaners claim to control allergens. But there is no regulation on the terms like ”hypoallergenic” so some products make false or exaggerated claims. AAFA joined with Allergy Standards Limited to create the asthma & allergy friendly® Certification Program. This program helps people make informed purchases for a healthier home. We test household products, such as air cleaners, against strict standards. If products pass our tests, they earn the asthma & allergy friendly® mark.

Watch on YouTube

Here are some things to keep in mind when shopping for an air cleaner.

Air and Room Capacity

Before selecting an air cleaner, consider the size of the room so the air cleaner you select is powerful enough. A useful way to determine this is by an air cleaner’s CADR rating. CADR, or clean air delivery rate, is the performance metric to indicate the effectiveness of an air cleaner. If you purchase an air cleaner with a CADR rating too low for your room, it will be ineffective. While CADR is a key measurement for selecting an air cleaner, MERV (minimum efficiency reporting value) is important for selecting the right filter. The MERV rating is a measure of the size of particles the filter will remove. HEPA filters are normally rated MERV 13.

PM2.5 vs. PM10

PM stands for particulate matter, and the number that follows it refers to the size of the particulate matter in microns. A micron is one-thousandth of a millimeter. (The period at the end of this sentence is about 400 microns!) The primary sources of these particles are cooking, automobile emissions, dust and fires. Larger inhaled particles are normally captured by the hairs in your nose, but particles of sizes less than PM10 can bypass this defense. The smaller the particle, the deeper it can make its way into your airways, and potentially the more damage it can cause. Particles that are defined as PM10 include dust, pollen and sea salt. Particles defined as PM2.5 are generally particles emitted from the burning of coal, wood, rubber and other materials.

Modes of Filtration

Air cleaners or air purifiers are designed to remove particulates and sometimes odors from the air we breathe. There are several ways they filter the air.

Media-based filter: Filters are generally ranked according to the particle size they trap. Over time, filters need to be replaced as they become clogged. The efficacy of a filter is dependent upon the integrity of the seals. Depending on how effective a filter is, it may be described as a HEPA (high energy particulate air) filter.

Electrostatic filters: As the particles in the air pass through the electrostatic filter, they receive a charge. This allows them to stick to metal plates in the air filter.

Activated carbon filters: These filters are made of porous carbon. As odors and gases pass through the carbon filter, they become trapped in the pores, unable to pass through. The pores may become clogged over time and will then need to be replaced.

Air Ventilation and COVID-19

It’s important to pay attention to your indoor air during the COVID-19 pandemic. Good ventilation in your indoor environment may help reduce the spread of the coronavirus. It may also affect the risk of transmission (how fast it spreads).

Keep your indoor spaces well-ventilated by opening windows or doors, using fans, running air cleaners, or using proper air filters in your HVAC system.

Good ventilation is only one of the ways to help reduce the spread of the coronavirus that causes COVID-19. Also follow these steps:

  • Get the COVID-19 vaccine.
  • Wear a mask.
  • Keep a physical distance from people outside your household.
  • Wash your hands properly and often.
  • Keep your asthma under control.

Air Purification

Ionizers and ozone generators produce different types of molecules but work in a similar way. They produce ions or ozone which is released from the air cleaner/purifier to be distributed around the room. Allergenic particles normally floating around a room have a neutral or no charge, so when they encounter ions or ozone, they become charged and can stick to surfaces around the home. This removes them from the air. They can then be removed from these surfaces by normal day-to-day cleaning.

Ozone is a gas that is highly reactive. It can be formed naturally or as a result of human activity. If ozone is inhaled, it can travel all the way to the lower respiratory tract where it can damage your lungs. Many electrical devices (including air cleaners) produce ozone as a by-product. This cannot be avoided. CERTIFIED asthma & allergy friendly® air cleaners are tested to ensure that they don’t produce harmful levels (greater than 0.05 parts per million) of ozone.

Ionizers release ions into the environment. Ions can be positively or negatively charged. Their main function in air cleaning is to pass their charge onto neutral air particles. By passing on this charge, it causes the particles in the air to stick to surfaces, removing them from the breathing zone. Research in the area of negative ions supports the safety of these ions. However, there is not as much research performed on positive ions. Anecdotal, unsupported research indicates that positive ions may have a detrimental impact on health. Air cleaners with an ionizing function must produce mostly negative ions to comply with certification.

UV light sources can sometimes be present in room air cleaners and in HVAC systems. UV light requires time to kill microorganisms (bacteria, viruses, fungi), but it doesn’t happen immediately.

Impact of Outdoor Air Pollution

Your indoor air is very much a function of your outdoor air. And pollution can cause inflammation (swelling) in your lungs. So if you live in an area with high outdoor air pollution, it transfers to your indoor environment. This will impact how often you need to change your filter and how long you need to run your air cleaner.

For example, smoke from wildfires can contain a wide range of particles at very small size – as low as 0.4 micron. Carbon monoxide, a dangerous gas, can also be produced during fires, so you could use an air cleaner with a media-based HEPA filter (to capture particles as low as 0.3 micron) and some type of carbon or zeolite filter to capture any gases that may enter your indoor environment. Due to the high air pollution following fires, filters would need to be changed more regularly and air intake should be set to recirculate rather than using fresh air intake.

Air pollution can also put you at a higher risk for more severe COVID-19. Several studies have found higher rates of COVID-19 deaths in areas with poor air pollution.1

Published November 2019. Updated October 2021.

Many products promise to help control allergens but not all of them do. When you are shopping for products for your home, look for the CERTIFIED asthma & allergy friendly® mark. It indicates the product has passed our testing standards to help you have a healthier home.

Visit to search for CERTIFIED products. There you can also learn more about the asthma & allergy friendly® Certification Program.


1. Coronavirus and air pollution. C-CHANGE | Harvard T.H. Chan School of Public Health. (2021, August 19). Retrieved October 26, 2021, from

Add Comment

Comments (7)

Newest · Oldest · Popular

What is the best room air purifier for removing mold and dust from indoor air. I suffer from asthma and am looking to purchase for the upcoming winter months. Mold and dust are my primary allergies. Also how can you determine if there is mold in your home? I have a bedroom where windows were replaced several years ago and has a musty smell.


Ult1Mat3x, based on the link you had, I would suggest talking to your doctor and beginning your search with the Aeromax 300. It's the only one on your list that is asthma & allergy friendly® CERTIFIED.

The asthma & allergy friendly® Certification program helps people make informed purchases for a healthier home. The program tests household products against strict standards. If products pass certain tests, they earn the CERTIFIED asthma & allergy friendly® mark.

Thank you for such a great article, a lot of useful info. 
I will be glad if someone could advise me air purifier for smoke from the list? I never used one, but decided to give it a try. My budget around ~150$. 
Share your experience if you ever used one. Thank you.


This is why companies of a business for mass people
I have said like hotels Uber Lyft Taxi Planes
This is example about Uber's
(Btw nothing against this guy so don't every want these people to get introubke and Amit not just them it's tooons of people, there needs to be law for boundary about air and containimant air in public spaces aka place of business)
These places are not pet stores.
This puppy is sooooo cute and sweet but that is why it is ignored
But I see and cannot filter my Uber rides I ha e even tried to email them and give comment and they just say ok and thank you and ignore it "bc people like animals"
This is what all businesses say to ignore addressing animals in business spaces (that are not pet shop)
Has got to be health law of nonpets (per indoor air health EPA STUDIES GOOD LORD IT was COPD day and did you know pet dander air clean air is part of the particulates to avoid bc they are triggers inflammers aswell, unless you are a PET SHOP.
It's all sorts of respiratory things besides allergies.
Also you got to do some kind of law like ASAP if people have an animal in there Uber or Lyft or whatever regularly they got to have a sign when you order it that it is a pet car. Because you got to be able to somehow filter out you have to have a no pet at all car
Same with AirBnB
Bc you can't tell
Same with shops (I just went to book store recently and had reaction which I DID MOT KNOW they place had 3 cats. A business store NOT A PET STORE
Just went to my local library and said they they are looking at having a dog there bc to help people be calm and read and so animal is there to encourage read???? That whole space will be ruined like an animal home doe snot matter that it's cleaned and vacuumed. Trust me I know! I am pretty sure people learned to read just fine in the 50/60/70/80s when dogs were not allowed to go everywhere we had lots of scientists and smart people back then. Kids can go to a pet shop that has classes and pet therapy socials activities or shelters of all these things.
-what will help kids read is healthier hrs of school, less over loads of home work, less over work hours of parent s so they can actually take their off time hours off and have their evenings with their family.
-With 40% of the population with anxiety, statistically Americans overwork about 13 hours a day healthier work hours and allowing people to have their off time without being contacted during their off time hours for regular work needs on their weekends and their off time hours in the evening when they're home why not let them actually cognitively rest from thework day OR HAVE some exercise time. Especially HR or the boss (if they don't have HR department) make sure that the person gets their regular sleep hours allowed in the work hours don't go into their sleep hours this is a very common issue in the workplace now. Because work starts to act like their work is considered an emergency. No what's an emergency is health issue event of a family member or a fire at home or a flood at your workplace. People need to start remembering what a work emergency is. The only type of work or emergency workers and how they deal with that is everyone's on shift work so matter what's going on of an emergency it just shifts to another person.
-how about allowing women to actually have their biological designed way to spend more time with their baby when they are born for example when you send women back to work at three months and their babies aren't even sleeping through the night and they are designed to eat more through the night because they're growing your cut and all sorts of sleep hours and ability of rest of need a parents. If a woman is not breast-feeding does not matter the woman and the spouse or whatever needs sleep during these times. If the woman is breast-feeding OMG even more for them to have that first six months off because when you're sleeping and not sleeping and breast-feeding and eating and pumping you need so much more rest and nutrients and the woman is speeding so they're the one that's not getting sleep. Also there's so much medical information about breast-feeding and then importance of night beads because the women's body makes more immunological and biological nutrients differently and fats in immune system needs during this time especially at night the breast milk is different. And when a woman goes back to work after three months usually because of the change you don't get as much rest you're working etc. your milk supply does drop (for most women there are exceptions of course). And now research even shows that by a parent not being as close during those development early years actually harms and delays cognitive and emotional development of the babies because they actually need this biological interaction for healthy development. A present caring parent Mom or Dad needs to be there!
(again I am a nurse my background experience is education, cardiology, chronic diseases, COPD, I'm pretty knowledgeable about women's health because I am a woman and i paid attention plus have heard all these issues of people when they do have babies, workplace health education and issues)
-as for social stuff people are so socially deprived these days because of overworking so everybody obviously needs to bring their pet everywhere or something I don't know, schools for one should have more outdoor fun activities for kids because they need some kind of physical activity play social time it's obvious need by what studies show, also adults need some kind of regular more often social activity enough time to be able to get together with friends and family again they're off time hours

-there are definitely some cultural things that have gone horribly in a direction and it really needs to be fixed, pets everywhere is one thing is other above about work hours protection parental time off and school social activity for kids and those evening hours for kids and homework hours all sorts of stuff, while we are at it pleeease get all
Smoking forms off business property so many people smoke just sitting in a parking lot or walking in and out of the store and you're always walking through their smoke because we all share the same walkway so the exposure doesn't really help they can't smoke in the building yes thank God for that wall thank you but the smoking in these places has got to stop. Because I'm at a open beach or outside of a restaurant or in line someone smoking a Vape because it doesn't make cigarette butt of litter but then you get chest tightness because of Vape chemicals (the they say oh the vape lie shpeeel vape is healthy better not smoke made my symptoms better no litter 🙄(but then it's nasty bad chemicals still in the air and super additictive bc of nicotine)
-maybe give some of theseabove to their perspective area section but we cannot act like that don't all correlate bc they are issues

OKBack to pets, this is too regular and growing bc no one is doing anything about it or health law. Everyone is pet bias or does not "want to disturb anyone to ask" bc pets are luvy Duvy and don't hurt anyone so they cannot cognitively logic bc their emotions. There has got to be law to explain and oversight enforce this logic
Darn Base ball stadiums are having A pet baseball game know where there are hundreds of dogs.
Imagine if they were goats, it is no different animal wise, doe snot make it no dander air health bc it's a dog/cat
This is 1 type of animal that everyone wants to bring everywhere
Just this past week another article how a guy snuck HIS CAT on a plane and the national main news article was saying "how it is so cute" and who would not want to sit by him
That stuff doesnot help! The mass public being everywhere.
-anothe think out there I think CNN about guy sneaking cat on plane and everyone including the news say how cute it was. That's not cute (yes in a way it is) BUT not on a plane close up air space thousands of ft in the air and you have NO ODEA beciajse someone wants to hide and look cute for their emotions!


Last edited by K8sMom2002

I receive your E mail and get a lot of information though your email.
thank you so much .This types of program should be establish in our
nation which directly affect the asthma patience.our nation is known
as the developing nation so that air are polluted day by day.So it
should be control by such type of program.I am student of social work
from Dibyabhumi Multiple College,kupondol,lalitpur

I hope my email response you very soon.

Thank you
Manoj Magar

Last edited by K8sMom2002
Link copied to your clipboard.