Air pollution, allergies, asthma – all of these are real problems that affect more and more people every day. But are indoor air purifiers a real solution to these problems? Do they really work, and if so, how?
More than 50 million Americans have health complications related to allergies and asthma, which is more people than ever before. Consequently, increasing numbers of people are concerned about indoor air quality and how it affects their health. It’s no surprise that people are looking for new solutions to this growing problem. Those solutions range from medication to lifestyle changes, or technology.
Do indoor air purifiers really do anything?
Air purification is a technology that has existed for many years. It is already effective in many industrial and commercial applications. But it’s only more recently that domestic air purifiers have rocketed in popularity. Manufacturers claim they can filter the air, kill bacteria, remove dust, eradicate allergens, and much more. But is any of that true, or are air purifiers just another fad?
In short, certain air purifiers are effective when used correctly, but by no means are all of them worth buying. Let’s find out more about the different types of air purifiers available on the market. We’ll cover how they work. We address whether they are effective. Lastly, we cover other general information you should know before buying an indoor air purifier.
How do air purifiers work?
In general, air purifiers are intended to clear indoor air of contaminants. The list of contaminants is long and includes dust, pollen, smoke, fur, and dander, and sometimes even mites, bacteria, and odors. Although they all have the same purpose, different types of air purifiers work in distinct ways. Where some are very effective, others are a scam. It is important to know what you should really be looking for.
The most common types of commercially available domestic air purifiers include UV filters, ozone generators, air ionizers, and HEPA filters. We’ll explain how each of these works, and then decide whether they are really effective.
Are UV Air Filters Effective?
UV air purifiers rely on ultraviolet light to kill bacteria and other harmful organisms. The high-frequency light essentially incinerates any live organisms that are exposed to it. UV light of a certain wavelength (between 260 and 270 nanometers) is proven to effectively kill bacteria and other microorganisms like dust mites on a cellular level. That is why it is often used to sterilize tools in medical and beauty applications, for example.
However, there’s a big “but” involved. For UV light to kill harmful microorganisms, continuous exposure is crucial. You can’t sterilize something just by waving a UV light around in the vicinity. The light needs to be constant and concentrated. Once you understand this, you will quickly conclude that most ultraviolet air filters are a scam. The particles in the air are pumped through constantly rather than being contained and treated with UV.
Furthermore, UV air filters will not help relieve symptoms of allergies, because bacteria are not allergens. Dust mites, which are allergens, can be killed by UV light when it is used properly, but they remain allergens even when dead.
In conclusion, air purifiers that use only UV light are usually ineffective at eradicating allergens, or any other particles. Even when used in conjunction with other air purification methods, UV air filtration does little other than hiking up the price of the appliance.
Are Ozone Generators Effective?
The most controversial type of air purifiers, ozone generators produce ozone molecules to allegedly clear the air of contaminants and even odors. So exactly how do ozone generators work, and can they really clean the air?
Most ozone generators expose regular oxygen from the air (O2 or dioxygen) to charged particles, causing some oxygen atoms to split and rearrange themselves into ozone (O3). It’s important to note that ozone is highly unstable and acts as a powerful oxidant. On the one hand, this makes ozone gas very effective in certain applications. On the other, it means that ozone is extremely dangerous for organic tissues.
Ironically, ozone is especially harmful to mucous and respiratory organs. Humans should never breathe in ozone, especially in high concentrations. This is why the gas is best for air (and water) purification in uninhabited, enclosed spaces. Examples include air purification and deodorizing following a fire or organic decay, or for sanitizing laundry, water, and food. All of those tasks take place in isolation away from people.
According to the US Environmental Protection Agency (EPA), ozone is not effective at eliminating contaminants, including odor, viruses, or bacteria, at levels that are safe for human exposure. If you don’t want to waste money or potentially damage your health, don’t buy an ozone generating domestic air purifier – they don’t work and are potentially dangerous.
Are Air Ionizers Effective?
Air ionizers are a common type of domestic air purifier. Apparently fancy people sometimes call them electrostatic precipitators, but that’s beside the point. They rely on electricity to charge air particles before discharging them in what is known as a “corona discharge”, or essentially a small electric field. This charged field interacts with airborne particles, either causing them to cluster together and settle, or attracting them to charged metal plates within the purifier. This removes the particles from the air, making them easy to clean away.
Air ionizing air purifiers can use fans or be fanless. Air ionizers with a fan tend to be more effective, but louder and more power consuming than fanless systems. Overall, air ionizers are effective at removing particles down to 0.01 microns in size (that’s tiny!), and are especially popular among people who live in big cities. However, they are less effective at removing larger particles and allergens like dust, pollen, dirt, and dander.
It’s also worth noting that they can potentially produce by-products like ozone and other oxidants, but these tend to be trace amounts below the industrial safety standard of 0.05 ppm.
Are HEPA Filters Effective?
High-efficiency particle air filters, or HEPA filters, follow a government efficiency standard. HEPA filters have to remove 99.97% of particles that are 0.3 microns or larger from the air to meet the requirements. For reference, the naked human eye cannot see particles below 10 microns in size. The standard was first developed to contain radioactive particles released in atomic research, but now has many applications including domestic air filtration.
How does HEPA filtration work? To summarize, air flows through a layered mesh of fibers such as fiberglass with diameters between 0.5 and 2 micrometers. These fibers not only capture particles like a sieve, but also force particles to become embedded or stick to the filter. Then, of course, the filtered air exits the filter and re-enters to the room, while the unwanted particles remain in the filter.
True HEPA filters are effective at removing contaminants and common allergens from the air, including dust, dust mites, pet hair, dander, molds, and pollen. It is important to note you will see many products with labels such as “HEPA-like” or “HEPA style”. Beware of these, and only purchase a legitimate HEPA filter if you want to see results.
How To Maximize The Benefits of Your Air Purifier
We’ve concluded that HEPA filters are the most effective air purifiers, and air ionizers are a close second. These are the two types that are most likely to clean the air in your home and help relieve symptoms from allergies or asthma. But what else can you do to ensure your air purifier is doing what it should?
Selection
When choosing an air purifier, ensure that it is appropriate for the room you will place it in. Ideally, you should consult a specialist when buying the product. You can also calculate how powerful your air purifier should be for the size of the room with a few simple calculations.
Firstly, you need to calculate the volume of air in the room (width x length x height). From there, you can determine which air purifier will be powerful enough by looking at the CFM (cubic feet per minute) in the product specifications. This tells you the volume of air the machine can filter per minute.
Using these numbers, determine the number of air exchanges the machine will make in the room per hour. This tells you how many times all of the air in the room will pass through the filter in an hour.
Do this by dividing the volume of air by the machine’s cfm specification to get the time it will take for the machine to filter all the air in the room once (in minutes). Then, divide this number by 60 minutes to get the exchanges per hour. The result should be at least 4, and ideally around 10. You can aim higher for better results, but this will likely lead you to purchase an air purifier in a higher price range.
Placement
The best place to put an air purifier in your home is the room in which you spend the most time. Contrary to popular belief, this is most likely your bedroom rather than your living room. Most people spend 6 to 10 hours in their bedrooms at a time, meaning they can benefit most from air purification while they are asleep.
Operation
Always ensure you read and follow the manufacturer guide. Most air purifiers need to be on all the time to work and should operate in a room with the windows closed. You’re trying to clean the air in your home, after all, not all the air in the world.
Maintenance
Depending on the air purifier you purchase, the appliance will require some maintenance. For example, replace domestic HEPA filters every 3 years or so to maintain their effectiveness. Air ionizers, on the other hand, require regular cleaning of the particle collection plates.
To make sure your air purifier continues to work effectively and safely, always follow the maintenance instructions in the manufacturer’s guide.