Indoor Air Quality Myths Debunked

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Myth 1: Houseplants Improve Indoor Air Quality

**The claim**: NASA research showed plants can remove VOCs from air. Put plants in your home and breathe cleaner air.

**The reality**: The 1989 NASA study was conducted in sealed biospheres — controlled chambers with no air exchange. In a real home, the air exchange rate is far too high for plants to have a measurable effect. A 2019 analysis published in the Journal of Exposure Science and Environmental Epidemiology calculated that you would need 680 plants per 10 square feet to meaningfully reduce indoor VOC concentrations.

Plants are pleasant. They do not clean the air in any practical sense.

Myth 2: Fresh Air Is Always Better Than Indoor Air

**The claim**: Open the windows to get fresh air.

**The reality**: This is situationally true. When outdoor AQI is low (below 50), opening windows is excellent ventilation. When outdoor AQI is above 100 due to wildfire smoke, pollen events, or high ozone days, opening windows brings polluted air inside. During high-AQI events, a sealed home with a running air purifier has significantly better air than an open-window home.

Check AirNow.gov before deciding to ventilate.

Myth 3: Air Purifiers Remove All Air Pollutants

**The claim**: An air purifier cleans the air in your home.

**The reality**: Air purifiers with HEPA filters remove particulate matter. Those with activated carbon remove some gases and odors. Neither captures everything. Specific pollutants that standard HEPA/carbon purifiers do not address well:

Radon (a radioactive gas; requires dedicated mitigation)
Carbon monoxide (a combustion gas; requires a CO detector and source removal)
Formaldehyde and high-VOC events (require high-weight carbon or purpose-built VOC filtration)
Ozone from outdoor events (standard carbon captures some but not enough during AQI events)

No single device solves all indoor air quality problems.

Myth 4: Indoor Air Quality Is Not a Serious Health Issue

**The claim**: The real pollution is outside.

**The reality**: The EPA estimates Americans spend 90% of their time indoors. Indoor air often contains 2-5 times the pollutant concentrations of outdoor air, sourced from cooking, cleaning products, off-gassing materials, mold, and HVAC systems. The World Health Organization classifies indoor air pollution as one of the top environmental health risks globally.

Myth 5: HEPA-Type and HEPA-Style Filters Are the Same as True HEPA

**The claim**: The filter says "HEPA" so it meets HEPA standards.

**The reality**: "True HEPA" or "H11/H12/H13 HEPA" have defined filtration standards (99.97% capture at 0.3 microns for True HEPA). "HEPA-type," "HEPA-style," and "HEPA-like" are marketing terms with no defined standard. These filters may capture 85-90% of particles at 0.3 microns, which is significantly worse than True HEPA — particularly for fine smoke particles and dander fragments.

If allergen reduction or wildfire smoke protection is the goal, True HEPA is the minimum standard.

Myth 6: Running an Air Purifier for an Hour Cleans the Room

**The claim**: Run your purifier for an hour when you want clean air.

**The reality**: Air purifiers must run continuously to maintain clean air in a room. Every time a door opens, someone enters, or cooking occurs, particle concentrations rise again. A purifier running continuously provides meaningful long-term particle load reduction. Running intermittently for an hour is better than nothing but provides only temporary improvement.

Myth 7: Ozone Generators Are Good for Air Purification

**The claim**: Ozone breaks down pollutants and kills mold, bacteria, and odors.

**The reality**: Ozone generators produce ozone (O3) at concentrations that are harmful to breathe. CARB and EPA both warn against residential ozone generator use. Ozone irritates the respiratory tract, worsens asthma, and reacts with household chemicals to produce formaldehyde and other secondary pollutants. The California Air Resources Board prohibits the sale of ozone-generating air cleaners in California for this reason. They are not recommended under any residential IAQ guideline.

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