Carbon vs. HEPA Air Filters: What Are the Differences?

To get the most out of your air purifier, you need to fit it with high-quality filters that remove pollutants from your indoor air. However, different filters target different kinds of pollution.

What are the differences between carbon and HEPA air filters? Do you need both in order to improve your indoor air quality? Let’s take a closer look at what these filters do.

Which Pollutants Are Removed by Each Filter?

HEPA and carbon filters both work hard to remove pollutants from the air, but they have different specialties.


HEPA filters, like the ones used in Smart Air’s purifiers, specialize in removing particulate pollutants from the air. Particulates smaller than 2.5 microns in size are often called PM2.5, and they can be harmful to the health of individuals who breathe them in regularly.

HEPA filters are highly efficient at removing PM2.5 from the air. The Smart Air lab has performed several overnight tests with a DIY HEPA filter strapped to a basic fan, and results showed up to a 90 percent reduction in PM2.5 after just a few hours. HEPA filters are also extremely effective at capturing larger particles like pollen, mold, dust, and pet dander, as well as smaller virus-size particles. Smart Air purifiers are designed to be powerful and effective at removing 99.97% of particulates in just minutes with the right sized purifier.


While reducing PM2.5 levels and other particulate matter goes a long way in improving air quality, gaseous pollutants can also cause a serious health threat. Long-term exposure to volatile organic compounds (VOCs), including formaldehyde and other dangerous gases from vehicle exhaust, power plants, and forest fires, can cause a serious health threat.

Smart Air tested an air purifier with and without a carbon filter by burning several cigarettes in a closed room, then running the purifier. Results of the carbon filter test showed that VOC levels reached zero after only a few minutes.

Who Needs HEPA and Carbon Filters?

Does every home and office really need both HEPA and carbon filters for adequate air purification? It depends on the air quality concerns specific to the location.


Air purifiers fitted with HEPA filters are a welcome addition to any home or office. You can use an air quality monitor to track pollution levels in your indoor air and increase your purification efforts when virus risk is high and when cold and flu season comes around.


While activated carbon filters are highly effective, not everybody actually needs one. Carbon filters are most helpful in the following applications:

  • Indoor spaces that have recently been painted, remodeled, or have new furniture
  • Homes where at least one resident smokes indoors
  • Locations situated near sources of gas pollutants, such as highways, factories, and power plants
  • Areas subject to smoke from nearby or even distant forest fires
  • Homes that use a natural gas stove or that often fry with cooking oils

What’s the Bottom Line?

If you’re wondering whether you need a carbon filter for your air purifier, think about the types of pollutants that affect your home or office. HEPA filters are the go-to for trapping particulates, while carbon filters effectively remove gas pollutants. If the pollution in your indoor air comes from cigarette smoke, smog, paint fumes, ozone, radon, or similar gas-based sources, be sure that your air purifier includes a carbon filter.

What are the differences between carbon and HEPA filters? The distinction lies in the types of pollutants they remove from the air. HEPA filters remove large and even nanosized particles, while activated carbon filters rid your indoor space of gaseous pollutants that pass right through HEPA filters. For high-quality activated carbon and HEPA filters for your air purifier, shop Smarter HEPA’s selection today.