If you’re shopping for a HEPA air purifier, you’ll quickly run into the next question: Do I need activated carbon too, for odors and VOCs, and how much carbon actually matters?
Here’s the key idea: a HEPA filter and an activated carbon system work differently, and solve different problems. A HEPA filter is great at trapping particles (dust, pollen, mold, pet dander, smoke particles). But activated carbon is great for odors and gases: it can adsorb certain gases and smells, reducing things like cooking odors, litter box funk, some chemical fumes, and parts of wildfire smoke that smell “acrid.”
Different Filters
But not all carbon filters are created equal, and the most important spec is often the one brands bury: how much carbon is in the unit (by weight), and how it’s packaged.
- Thin carbon “sheets” or lightly carbon-coated prefilters can help a little with mild smells, but they saturate quickly.
- Pelletized or granular carbon beds (heavier, thicker cartridges) generally perform better and last longer, especially for persistent odors.
- For VOC-focused use (paint, solvents, new furniture off-gassing), you typically want more than a token amount of carbon and good airflow design. Otherwise, you’ll get a brief improvement that fades.
Measuring Carbon
So how much is “enough”? There’s no universal number, because performance depends on airflow, dwell time, and the specific gases involved. Still, a practical rule is: if the purifier doesn’t clearly state carbon weight, assume it’s minimal. If odors or chemical sensitivity are a real concern, look for models that advertise substantial carbon mass (often measured in pounds) and offer readily available replacements. This also depends on configuration of filters and the type of carbon used.
Bottom line: If your main issue is allergies or dust, HEPA alone may be plenty. If you care about smells, smoke odor, or VOCs, carbon can be worth it—but only if there’s enough of it to do the job.
Two more quick tips: first, calculate your air changes appropriately for your desired goal. Second, run the unit on medium instead of high speed, to increase the dwell time of the contaminants near the carbon.The Lulay Team at USAirPurifiers is a family and veteran owned U.S. business, and we are truly here to help with your best interests in mind. Our team will help you to purify your indoor air and get a better result with modern technology that fights air pollution where it lives – and where you live, too! Make an investment in your health and the health of your family, to breathe easier all day and all night.