Surprisingly, indoor air can often be more polluted than outdoor air. Particles from home heating and cooling systems, tobacco smoke, off-gassing from furniture and building materials, and mold spores can all contaminate indoor air. Of course, outdoor air pollution can also make its way indoors when windows are open – traffic pollution particles in built-up areas and next to roads, chemical pesticide sprays in agricultural areas, and even mercury and ozone that are carried by wind over long distances.
Earlier this year, a first-of-a-kind study published in the journal Lancet Planetary Health suggested that indoor and outdoor air pollution (specifically nitrogen dioxide) from traffic emissions cause 11,000 new cases of asthma per day in children around the world (the equivalent of four million per year). The top countries for new incidences of childhood asthma include UAE, Canada, Taiwan, USA, UK, Australia, France and Germany. Air particulate pollution is also linked to cancer, heart attacks, stroke, preterm births, and other health problems. The World Health Organization (WHO) links household air pollution to around 3.8 million premature deaths worldwide.
Does Using an Air Purifier Really Make a Difference?
More research would of course be nice to answer this question, but this is an area that has been studied. Here are some examples: One prospective, observational study carried out in Taiwan found that air filter use was a protective factor against the development of allergic rhinitis, atopic dermatitis (eczema), and asthma. An intervention study conducted in California found that (unsurprisingly), using an air purifier resulted in significant improvements in nasal symptoms in children with hay fever. The Samsung air purifier used in that study contained a HEPA filter that captured particles 0.3 microns and larger. Another HEPA air filter used in a 2018 study in China found that it improved symptoms in patients with hay fever.
Plus, we have a significant amount of clinical experience to say that indoor air purifiers, in combination with other interventions, can make a difference when dealing with many health challenges. The WHO recommends air filtration to reduce the risk of air pollution-related diseases, and we wholeheartedly agree.
What Air Purifiers Can and Can’t Do
Sorting through the ins and outs of air purification can be a minefield. Here are some things to know:
Some marketing statements can be misleading. For instance, when a manufacturer states that their machine removes 99% of air particles, generally that statement (which may or may not be verified by independent testing) only applies to certain types of air particles such as smoke, dust and pollen. Filtering (especially with a HEPA filter) is helpful for those air particles. It may also help to lower circulating levels of airborne fungi. However, it doesn’t get any of the gases such as volatile organic compounds (VOCs, including benzene, xylene, toluene and formaldehyde from furniture and paint surfaces) or nitrogen dioxide (from traffic pollution).
To address pollutant gases, we look to purifiers that contain activated carbon as an adsorbent. While again we would love to see more studies in this area, there are some data that indicate that activated charcoal is able to remove some gases such as formaldehyde. Carbon filters may also help capture smaller wildfire smoke particles and odors. Indoor plants may also shine in this area and can complement particulate air filtration and carbon adsorption.
Alert! Some air purifiers also use electrostatic precipitator or ionizer technology that can produce ozone, another air pollutant. We recommend avoiding any ozone-producing models.
Our Top Picks for Air Purifying Machines
We’ve compiled a list of our top picks for indoor air purifiers. We lean on Consumer Reports where we can, but Consumer Reports don’t test all the options that are available. For that reason, you’ll also find some other purifiers in here that we especially love.
Consumer Reports Top Recommended and Multipurpose
Blueair Classic 605 and Blue Pure 211+
What is it: HEPA particle filtration plus carbon filter
Cost $750 and $250
Coverage 700-800 sq ft and 540 sq ft
Filtration Level 0.1 microns
Yearly Replacement Filter Cost $250
Clean Air Delivery Rate (CADR)* 500 and 350
These two Blueair purifiers steal the top two spots in the 2018 Consumer Reports Room Air Purifier rankings. The good news is that lower-cost Blue Pure 211+ performs nearly as well as the higher-priced Classic 605 with an excellent CADR. Both are not particularly quiet but have an average noise level for air purifiers. The WiFi feature on the Classic 605 enables control through Alexa or the Blueair app.
Best Coverage Area
What is it: HEPA particle filtration plus carbon filter
Cost $899
Coverage 1,125 sq ft
Filtration Level 0.003 microns
Yearly Replacement Filter Cost $125
Clean Air Delivery Rate (CADR) 330
The IQAir purifier covers an impressively large space with similarly high-quality filtration making it a good option for an open living area, shared office space or larger room. Unique features include the ability to filter some of the smallest particles through the hyperHEPA filtration.
Works for Bedrooms and Smoke
What is it: HEPA particle filtration plus carbon filter
Cost $250 and $240
Coverage 465 sq ft
Filtration Level 0.3 microns
Yearly Replacement Filter Cost $60
Clean Air Delivery Rate (CADR) 250
While it doesn’t capture as small particles as the others above, Consumer Reports states still recommends these Honeywell models as effective at removing dust, smoke and pollen even on their lowest (quietest) speed, making them a potentially good choice for bedrooms. The HPA300 is especially noted for its effectiveness at removing smoke particles, moreso than other purifiers.
For Extra Sensitive Individuals
L. Foust Co. 160R2 (Room), 160AN (Auto) and 160DT (Desktop)
What is it: HEPA particle filtration plus carbon filter
Cost $451, $399 and $396
Coverage 500 sq ft, 500 cu ft interior and 180 sq ft
Filtration Level 0.1 microns
Yearly Replacement Filter Cost $220 for the 160R2
Clean Air Delivery Rate (CADR) not reported
While there isn’t any independent data verifying this, E. L. Foust & Co has published data that indicate effective removal of formaldehyde, phenol, ozone, hexane, mercury and nitrogen oxides. The all-metal construction means the purifiers are free of plastic and adhesive off-gassing. Since we work with many individuals who have heightened environmental and chemical sensitivities and allergies, this is a frequent go-to. If you live in a heavily-polluted area, or are testing positive for pollutant gases in your Functional Medicine labs, these are a top choice.
*Clean Air Delivery Rate (CADR) is an indication of the volume of filtered air delivered by a portable air purifier the higher the number, the more effective
Don’t forget your HVAC (heating, ventilation and air conditioning) system! Using a MERV12 or higher performing air filter in HVAC systems reduces common asthma and allergy triggers. Don’t forget to change your filters at appropriate intervals. Note again that HVAC filters capture varying levels of particulate matter, but not gases.
Selecting Indoor Plants for Removal of Toxic Gases
Plants have the ability to sequester or metabolize some toxic environmental pollutants, converting them into harmless by-products. Data on the effects of plants on indoor air quality started with a NASA study published in 1989 exploring the possibilities of long-term space habitation. It was recognized at the time that air in a tightly-sealed space capsule would quickly become contaminated by airborne chemicals that would be detrimental to human health. Viable solutions to this dilemma were needed.
More examples of the consideration of plants for air cleansing have appeared since. Issues with temporary housing used following hurricanes Katrina and Rita that was causing respiratory illnesses and rashes was successfully resolved by using plants to clean the air of formaldehyde. Companies such as Ferrari have used plants in part to clean the air for their employees; Ferrari has two large areas for plants and small trees in the middle of its body shop, as well as many other green areas and plantings throughout their campus in Maranello, Italy.
Research has shown that the presence of plants in an interior working environment may improve worker productivity, reaction times (improved 12% in one study!), creativity, morale, and reduce stress and absenteeism. Studies have also shown that interior foliage changes air particle accumulation – rooms containing vegetation have lower levels of air particles.
Different plants may attract and remove specific toxins better than others, though, making it a good idea to use multiple species. Here’s a rundown of the top plants for different types of airborne toxins (peer-reviewed Journal references for this list are here, here, here, here and here).
Plants that Have Been Shown to Remove Specific Toxins
- Trichloroethylene: Epipremnum aureum (devil’s ivy or ‘money plant’)*
- Benzene: Epipremnum aureum (devil’s ivy or ‘money plant’)*, Spathiphyllum spp. (peace lily)
- Toluene: Hedera helix (common ivy), Philodendron spp., Sanseviera spp. (devil’s tongue or snake plant)
- Xylene: Zamioculcas zamiifolia (ZZ plant)
- Formaldehyde: Osmunda japonica (Japanese royal fern), other ferns, Spathiphyllum spp. (peace lily), Chlorophytum comosum (spider plant)
- General VOC removal: Purple waffle, Purple heart, English Ivy, Asparagus fern, Variegated wax and Crassula portulacea (jade plant)
- Polycyclic aromatic hydrocarbons: removal attributed to bacterial species present on leaves of many ornamental plants (nonspecific)
- Mercury vapor: Tillandsia usneoides (Spanish moss)
- Ozone: snake plant, spider plant, golden pothos
- General toxin removal: Spider plant, peace lily, english ivy and golden pothos
*Grown on an activated carbon filter system. Activated carbon is available for potted plants.
While it’s nice to have some data that link specific species to the removal of specific toxins (especially if you know you have specific exposures or an elevated body burden of a specific toxin), the research isn’t that extensive, and so we would still recommend a variety of species. Keep the air in your living and working spaces moving, too, since air movement increases the effectiveness of plants at removing toxins.
Fascinating Fact! While you may think that plants collect and detoxify air pollutants through their leaves, it’s actually their roots and the plant’s associated microorganism population that take up and process toxins.
Things to know about keeping healthy houseplants – avoid introducing plants to your home that have been sprayed with pesticides or come in plastic pots. Water your plants appropriately but don’t allow them to become moldy. Dust leaves to maintain their effectiveness and reduce the room’s dust burden.
Final Thoughts
Air purifying strategies are great, but remember that reducing indoor air pollutant sources helps to minimize their levels in your home or office to begin with. Use building and decorating products that have no or fewer toxin emissions. Don’t use or store chemicals, solvents, glues or pesticides. Keep your home smoke free. Use exhaust fans in kitchens, baths and laundry areas. And minimize the use of candles and wood fires. Ask your government representatives to prioritize clean outside air initiatives, to minimize the burden on your inside air too.
Thank you to Lindsey Crenshaw MS CHES who is completing her nutrition residency with us to complete her CNS supervised experience hours, and who contributed to the research for this article. Lindsey holds a degree in Functional Medicine and Human Nutrition from the University of Western States and is also a Certified Health Education Specialist through the National Commission for Health Education Credentialing. Lindsey began her career in the field of corporate wellness helping employees find their healthier self through fitness, mindfulness, and lifestyle change. A passion for nutrition grew from her experiences with clients in this setting and led her down the path towards functional nutrition.