HEPA vs. carbon filter, which do I need in my home air purifier? You can’t do any kind of a head-to-head filter performance comparison between a HEPA filter and a carbon filter. Because these two air filters are made differently, work differently, and do completely different things.
The end goal shouldn’t be to pick one filter over the other. Hint: You likely need both.
What Is an Activated Carbon Air Filter; How Does It Work?
An activated carbon air filter is a dedicated odor and VOCs removal filtration media made of highly porous charcoal. Unlike HEPA, this isn’t a mechanical filter. Instead, a charcoal filter gets rid of unpleasant odors and gaseous pollutants through a chemical process called adsorption. Adsorption causes filtered pollutants to stick to the sorbent and remain there.
Adsorption is completely different from absorption. During absorption, whatever is being absorbed never becomes chemically bonded with the absorbent. The way water seeps into a sponge would be a good analogy for this process.
In contrast, during adsorption, the adsorbed substance chemically attaches to innumerable micropores in the adsorption site.
For comprehensive odor and VOC filtration, the airstream shouldn’t pass through the carbon filter too fast. The right amount of airflow allows for enough dwell time so that the media can remove as many pollutants as possible.
How is an Activated Carbon Filter Made?
Activated carbon or charcoal is manufactured from small pieces of carbon-rich materials. Manufacturers use any of three kinds of carbon sources to make activated carbon. These sources include wood, coconut, and coal. Options made from coconut carbon tend to be better than those made from wood or coal.
Manufacturers blow steam through the carbonaceous material to create numerous tiny pockets that substantially increase the media’s surface area. One gram of activated carbon filter provides a surface area of between 10,226-21,528 sq. ft. according to ScienceDirect.
The central aim of activating ordinary carbon is to build up its microporosity. This incredible microporosity provides storage for adsorbed chemical pollutants. These bothersome organic chemical compounds include toluene, xylene, benzene, and formaldehyde.
High-grade activated charcoal eliminates gaseous pollutants and odors remarkably well. It’s your best bet when dealing with lingering cooking smells, pet odors, MJ smoke, and stinky tobacco smells.
What’s a HEPA Filter?
According to the Environmental Protection Agency, a HEPA filter should have a demonstrable minimum filtration efficiency of 99.97% in catching airborne particles sized 0.3 microns in diameter. Don’t confuse HEPA filters with HEPA-type filters because they’re different. I recently wrote a resource that lucidly explains the difference between HEPA and HEPA-type air filters.
Are HEPA Filters Same as Activated Carbon Filters?
No, HEPA filters aren’t the same as activated carbon filters. HEPA filters mostly capture particulates or solid air contaminants while activated carbon filters focus on odor and chemical compounds elimination. These filters are typically used in industrial air cleaning systems and standalone units for home use.
Activated carbon filters are more versatile and are used in both air purifiers and water purifiers. In air purifiers, carbon filters help battle different kinds of odors.
In water purification systems, Granulated Carbon Filters (GAC) clean up impurities including Volatile Organic Compounds, pesticides, chlorine, hydrogen sulfide, and nitrates. When the filtration process completes, the water is odorless and tastes better.
Do Carbon Air Filters Work?
Yes, they do. Traditional societies in different parts of the world have used common carbon to purify water for thousands of years.
Historians believe that the Egyptian Civilization was the first known society to use carbon for water treatment around 1600+ years ago.
Pharaoh’s Egypt was also the first known region to use carbon for medical purposes. They used charcoal to tackle odors from wounds starting around 1500 BC.
Ancient sailors were another early adopter of carbon filtration technology. These wise adventurers put carbon on the inside of water storage vessels to keep the precious liquid tasting nice and fresh throughout the months-long voyages.
Today, people use activated carbon to adsorb various kinds of indoor odors. Do you live with someone who treasures tobacco? Tell them to stop smoking inside the house already! Meanwhile, you can use activated charcoal to deal with some of the stubborn secondhand tobacco smoke. As long there’s enough carbon in the filter, it’ll eliminate the odor.
But do activated carbon filters remove carbon dioxide? No, carbon filters are extremely limited when it comes to carbon dioxide removal. Consider installing a carbon dioxide detector to manage your home’s CO2 levels.
Here’s good news! One study I read while researching for this post suggested that modifying activated carbon in certain ways might increase its adsorptive capabilities for CO2.
Not All Carbon Filter Air Purifiers Remove Odors and VOCs
If you think every air cleaner advertised as having activated charcoal is an awesome odor eliminator, you’re mistaken. Choose a purifier whose smell filter contains enough carbon. But how much carbon should the filter have? If it says 10 or more pounds of activated carbon, then that’s OK. Unfortunately, most manufacturers don’t state how much charcoal their smell removal media contains.
How Do I Know It’s Time to Replace My Activated Carbon Filter?
In most cases, the only way to know it’s time to replace your activated charcoal filter is when it begins to give off a strange odor.
What else could cause this odd odor? The performance of an activated carbon filter may vary depending on the current prevailing conditions in your home. Changes in temperature and humidity can cause the filter to release some of the trapped organic contaminants back into the air.
Some compounds may not stick onto the surface of the media strongly enough. Such pollutants may get released in favor of those with a greater affinity for the sorbent.
Are Activated Carbon Filters Better Than HEPA Filters?
Activated carbon air filters aren’t necessarily better than HEPA filters. But they perform certain filtration tasks better than HEPA. HEPA filter media are best at tackling microscopic airborne particles including tobacco smoke particles, wildfire smoke particles, household dust, tree & grass pollen, mold spores, pet dander, and more.
IMPORTANT: HEPA filters DO NOT remove smoke smell and odors of any kind. That’s what activated carbon filters are for.
Activated carbon filters outshine their HEPA counterparts at removing gaseous and chemical compounds. They’re the best filters for eliminating car exhaust fumes, pet smells, fumes from DIY paint jobs, kitchen smells, and more.
Neither filtration system catches 100 percent of particles from contaminated indoor air though. It’s best to use these particle filtration technologies together in the same unit or in conjunction with your HVAC system.
Do HEPA Filters Contain Activated Carbon?
Most HEPA filters today come with a layer of activated charcoal on one side. If the device you’re considering is described as a True HEPA air purifier, chances are it also offers carbon filtration. But it might be possible to find a dedicated odor remover that offers carbon filtration and no HEPA filtration.
In some air purifiers, the carbon filter and HEPA media are separate. With such units, you can replace each filter individually.
Others use 3-in-1 cartridge HEPA filters that offer 3-stage air purification. This 3-in-1 cartridge filter consists of a prefilter, a HEPA filter, and a carbon filter in the same media. With these combo HEPA-activated carbon filters, you can’t change one without changing the other.
Should an Activated Filter Go Before or After the HEPA Filter?
In most cases, the HEPA filter goes into the air filtration chamber first followed by the charcoal filter. So, the charcoal filter stays in front of the HEPA filter in that case. And the prefilter sits closest to the cover. The prefilter traps larger debris. This adds to the other filters’ lifespan.
The charcoal filter may clip onto the frame of the prefilter or attach to the HEPA media. Often, you can peel off the charcoal media and replace it if necessary without replacing the other filters.
Activated Carbon Air Filter Lifespan: How Long Do They Last?
Activated carbon air filters naturally have a shorter lifespan compared to HEPA filters. Their lifespan sits anywhere between 2 and 3 months. Actual longevity depends on the pollution levels you’re battling. Fortunately, odor filters aren’t very expensive.
HEPA Filter Longevity: What’s The Lifespan Look Like
HEPA filters are pricier than carbon filters, but they last considerably longer. Most HEPA filters serve allergy sufferers for anywhere between 6 and 12 months. Better ones can last up to 24 months or even longer. In some top-of-the-line air cleaners, it can last up to 5 years!
Which Filter Type Should You Choose?
Well, that depends on your specific air cleaning needs and budget. If you’re looking for an affordable air filter for capturing mostly tobacco smoke and pet odors, get an activated carbon air filter.
But if particulates such as pet dander, dust, pollen, and mold spores are the most concerning contaminants in your home, definitely HEPA. But why use one when you could use both filters and get cleaner, fresher, healthier air?
Keep Your Purification System Clean
No matter which filter you choose, keep it clean. Also, replace the filter when the time comes. Usually, that’s when its performance starts to decline (for HEPA). Or when you start noticing strange smells from your carbon filtration system. It’s critical to replace filters regularly for a pollution-free home.
How Do You Clean Activated Carbon Air Filters?
Changing this filter out when it gets saturated is best. But if you choose to clean it, well, clean it. If it’s not too thin that a vacuum’s suction would suck it up or even shred it, you could vacuum-clean it lightly.
Use your vacuum cleaner’s dust brush attachment to clean each side of the charcoal filter. Here’s a more detailed post on how to clean an activated carbon filter in an air purifier.
Anything I left out? Write a comment below.