What is the Best Air Purifier for Smoke?

Many now understand the dangers of secondhand smoke, and as a result, legislation has followed to limit indoor exposure. Yet sometimes you cannot fully control the source of smoke. If your neighbor is a smoker and secondhand smoke drifts from their apartment into yours, then you might be forced to deal with it. Or maybe you live in a fire-prone area, and wildfire smoke is a real problem. Whatever your situation, there are steps you can take to improve it, and often an air purifier can help.

If you are faced with the task of finding the best air purifier for smoke, you probably know there is a lot of contradictory information out there about what is the best one. And the main reason for this is that smoke is a highly complex pollutant. People might use HEPA filters to filter particles in the air, but smoke is much more than just particles. It is also made up of harmful gases. There are also air purifiers out there solely designed to filter gases and odors. However, what is the best air purifier for smoke? Ultimately, it depends on the situation. Please remember that no matter how good an air purifier is at removing smoke, it will never be a complete solution and should not be a substitute for reducing or eliminating the source of smoke whenever possible.

Why is smoke so essential to get rid of?

You already know that smoke is harmful to health. But exactly how harmful can further inform your decision to take action. If you have children, older adults, or someone with a respiratory condition like asthma in your family, they are more at risk.

Smoke from wildfires, though harmful, is at least temporary. If you are trying to filter smoke from a regular source like secondhand smoke from a neighbor, it is even more important to take the first line of action, like asking them to avoid smoking nearby. The National Institutes of Health (NIH) says there are at least 250 harmful chemicals in tobacco smoke, and at least 69 are carcinogens, such as arsenic, benzene and formaldehyde. Secondhand smoke may cause disease and premature death in nonsmoking adults and children. For children, exposure to secondhand smoke can cause an increased risk of SIDS, colds and bronchitis, and for those that already have asthma, can worsen their symptoms.

best air purifier for smoke - pollutants diagram of particles and gases

Diagram: What is smoke? Smoke is made up of tiny particles and harmful gases.

What is smoke?

If there is nothing more you can do to reduce you and your family’s exposure to smoke, your next best option is an air purifier. Before you start looking for one, you need to know exactly what you are dealing with. As mentioned before, smoke is far from easy for an air purifier to address. The reason for this is because smoke is made up of two major types of pollutants: fine particles and gases, and usually an air purifier is designed to filter either one or the other and not both.

Particulate matter. The first major type of pollutant in smoke is particulate matter, or fine particles. Particulate matter in smoke is a mixture of solids and liquid droplets suspended in the air. Though some of these smoke particles you can see are dark or large enough to be seen by the naked eye, others are so tiny they can only be seen through an electron microscope. These fine particles are especially dangerous to health because they are small enough to enter the lungs, and may cause burning eyes, a runny nose, or even lung disease. Particulate matter in smoke can be smaller than 0.1 micrometers in size.

Gaseous pollutants. Particulate matter is serious enough, yet it is only half of the story. Smoke also contains harmful gases. These gaseous pollutants include gases associated with combustion, like carbon monoxide or nitrogen oxides. Other gaseous pollutants are organic chemicals that are separate from particles–these organic chemicals are specifically called volatile organic compounds, or VOCs. The known carcinogens benzene and formaldehyde, among others, are VOCs.

How are air purifiers designed to address smoke?

Now you know exactly what you are dealing with when it comes to smoke–harmful particles and gases. Why is that so important to understand? It is because the best air purifier for smoke has to reduce both. Like mentioned before, usually air purifiers are designed with only one technology–either they filter particles, or they filter gases. Be careful of some air purifiers that say they are the best for smoke, yet only filter one type of pollutant.

Below is information about the four types of air purifiers that could be used for smoke: HEPA (to filter particles), carbon (to filter gases), hybrid (to filter both) and Molekule (to remove both). It is important to understand what these units can do for smoke, so you can determine which air purifier will be the best one for your situation and the type of smoke you are dealing with.

HEPA filters. If you want to filter particles, you might consider a HEPA filter. Yet whether or not an air purifier can remove a particle is based on size. A rating called a MERV rating (from 1 to 20) tells you the smallest size of particle an air purifier filters. The higher the rating, the smaller the particle it can filter.  A HEPA filter is designed to remove 99.97% of particles that are 0.3 micrometers or larger, with the idea that the most penetrating particle size (MPPS) is very near to 0.3 micrometers.

However, the tiniest particles in smoke are smaller than 0.3 micrometers. Also, depending on the nature of the flow and the HEPA filtration media, the MPPS may be significantly less than 0.3 micrometers. This means that the most dangerous, tiniest particles in smoke might not be filtered by a HEPA filter. There is an exception: The highest level of HEPA filter (with a MERV of 20) can remove 99.99% of particles in the 0.1–0.2 micrometer range. However, these filters are used in electronics and pharmaceutical manufacturing and as a consumer you probably cannot buy one.

But even a perfect HEPA filter is only doing part of the job when it comes to smoke. Much of the harm done by smoke comes from gaseous pollutants like carcinogenic VOCs, which a HEPA filter cannot remove.

Carbon filters. These are designed to remove gases and odors, though of course none can remove them all. Carbon filters are primarily useful for organic compounds–also known as VOCs. Please remember that carbon monoxide is likely not addressed by any type of air purifier, and therefore carbon monoxide sensors (for detection) and adequate ventilation (for mitigation) are highly recommended where carbon monoxide may be an issue.

There are a couple of problems associated with carbon filters. One is they can quickly become saturated and have to be replaced often. If the carbon filter becomes saturated, toxic gases can be released from the filter back into the air. Even if the filter is not saturated, but the composition of gases in the air changes (say if a window is opened and more air is let inside) it has been shown that gases on the filter surface can also be released back into the air (referred to as “outgassing”).

What does this mean for you if you are thinking of using a carbon filter for smoke? Because it must be replaced according to saturation levels, it is best to get one with a high quantity of carbon to allow for a greater surface area for gases to stick to.

Hybrid air purifiers. There are a few air purifiers out there with two types of filtration, like a HEPA filter combined with a carbon filter. They are designed to filter both particles and gases, yet this may not make them necessarily better for smoke. The EPA states that their effectiveness may decrease because when the filters are arranged in a series, it can introduce greater air resistance. This in turn can reduce the delivery of clean air to the room or even cause some of the room’s air to miss the filter altogether. Reduced air delivery means that the device may not produce enough clean air to circulate throughout the room, and if the air bypasses the filter, then contaminated air may flow through the unit and not get filtered at all.

PECO air purifier. The PECO technology (the technology inside a Molekule air purifier) can entirely eliminate the dangerous VOCs in smoke. The Molekule air purifier also contains a mechanical filtration stage where air is first filtered of particles. The second stage is different from the others because though it removes gases from the air like a carbon filter, it uses a chemical reaction to destroy them completely. There are no organic vapors that stick to a filter that can be released back into the air. However, this process takes time, which could be longer than the time it takes for a carbon filter only to absorb the vapor.

Best air purifier for smoke - HEPA vs PECO for VOC destruction graph

Volatile organic compounds (VOCs) are harmful gases present in smoke. A HEPA filter is designed to filter particles and not gases, while Photo Electrochemical Oxidaton (PECO) can address both types.

To learn more about how different air purifiers work on smoke, click here.

What is the best air purifier for smoke?

Now you know the four air purification technologies that could be used for smoke. You have also read about their limitations. However, what you may not know is how each of them applies to your particular situation.

Ultimately, the best air purifier for smoke depends on if the device is needed for the short or long term, whether the source of the smoke is from wood/wildfires or tobacco, and what is the level of exposure.

For wildfire smoke (short-term):

Air purifier for wildfire smoke - trees surrounded by smoke

You have two options for wildfire smoke, where short-term exposure is hours or weeks. The major concern here is particulate matter. Because a HEPA filter can filter most particles pretty well, it is an acceptable option, though it cannot remove the tiniest ones.

However, a HEPA filter cannot address the gases or odors of wildfire smoke. The best option for wildfire smoke if you want to filter both particles and gases is a PECO air purifier.

For tobacco or wood smoke (high-level exposure, long-term):

This kind of situation most likely does not apply to you. This is when tobacco smoke is often produced inside the home or a home where wood stoves (commonly used in developing countries) release a lot of smoke into the air. Here, both particles and gases would be a significant concern. There really is no air purifier that can sustain cleaning the air in this type of situation. Some hybrid air purifiers will void the warranty in this case. The only real solution would be to smoke outside and upgrade or replace wood stoves.

For secondhand tobacco/wood smoke (low-level exposure)

best air purifier for cigarette smoke - hand with smoking cigarette

This is a situation when secondhand cigarette smoke drifts inside from a neighboring apartment or when there is brief exposure to secondhand or wood smoke. In this case, the best air purifier would be the Molekule air purifier, which addresses both of the major pollutant types in smoke. In Molekule’s case, the gaseous pollutants (except carbon monoxide and other combustion pollutants that no air purifier can address) will be eliminated entirely.

Another option for low levels of secondhand/wood smoke is the hybrid air purifier, which also addresses both particulates and gases. However, in the long-term, it might come at a higher cost because of frequent filter replacements. If you choose a hybrid air purifier, a large quantity of carbon should be inside the filter to prevent too frequent replacement.

How do you reduce the smell of smoke?

Now you know what the best air purifier for smoke would be for your situation. However, another concern may linger—the smell. The best air purifiers for the odors of smoke include a carbon filter as a short-term solution (though these must be replaced often if there are high levels of smoke), or a Molekule air purifier as a long-term solution. However, the smell will remain even if you use an air purifier. Tobacco smoke sticks to everything—the carpet, the curtains, the sofa, even the paint on the walls. That is because so much of the odor (and chemicals) from smoke get trapped in rugs, curtains, and furniture. The California Department of Public Health describes the residue that tobacco products leave behind as thirdhand smoke.

To dramatically reduce the levels of thirdhand smoke, you usually have to replace or substitute materials, such as change the carpet or repaint. Comprehensive cleaning, such as steam cleaning all the rugs and carpets, curtains, and even the upholstery on your furniture, can help to reduce odors and thirdhand smoke, though it is hard to clean completely. If your home has been exposed to smoke for a very long time (years or decades), this means that layers of thirdhand smoke have built up over a long time on household surfaces and in dust–in that case, it may be necessary to do renovations like replacing wall boards and upholstery.

What is the best solution for smoke?

You already know the answer to this question. The best solution for smoke is to remove (or reduce as much as possible) its source. But you might not be able to do that always. In the cases where have no other choice but to deal with smoke, an air purifier can help reduce levels of pollutants, and each type discussed in this article can offer benefits for reducing smoke. You should consider your particular situation and budget to invest in the best air purifier for your needs.

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