Can Activated Carbon Remove Formaldehyde?

Can activated carbon filters remove formaldehyde and VOCs? Earlier tests from Smart Air found that carbon can reduce VOCs from cigarette smoke. But formaldehyde and VOCs in general are particular concern for many people. We put activated carbon filters to the test by ordering formaldehyde straight from the factory and … Read more

Ford Gurgaon office

Smart Air Provides Clean Air to Automobile Giant Ford

Right after moving to their new office in the Chimes building in Gurgaon, Ford India was experiencing problems with outdoor particulate pollution (PM2.5) and chemicals (VOCs) off-gassing from new furniture, carpets, paints, and other remodeling work. To tackle these problems and protect the health of their staff, Ford India reached … Read more

PM2.5 vs. PM10: The Difference in Particle Air Pollution

PM2.5 and PM10 are the two types of air pollution that the WHO estimates affect “more people than any other pollutant,” but they are different. Here’s how the two contrast. PM2.5 vs. PM10 The difference between PM10 and PM2.5 is size. But before we get to size, “PM” refers to particulate … Read more

Can Plants Filter Out Formaldehyde and Benzene VOCs?

There’s a popular conception that plants are effective at filtering out VOCs like benzene and formaldehyde, but can plants filter harmful chemicals at meaningful levels? Recent studies have found that that plants have no detectable on removing formaldehyde or other gas pollutants under real-world conditions. Why People Think Plants Can … Read more

Activated carbon air purifier VOC

Does Adding a Carbon Layer Reduce Particulate Effectiveness?

I recently published tests showing that carbon actually removes VOCs. But adding that carbon layer raises a question: adding carbon means the fan has to power through yet another layer of resistance. Does that make purifier less effective at removing particulates?

Test Method

To test this question, I ran 10 room tests with the Cannon and 10 tests with the Original DIY in the same 15m2 Beijing apartment as my earlier tests without a carbon layer.

 

Dylos particle counter pollution test

 

I measured how much particulate it removed with a Dylos particle counter and compared the particle counts (1) before I turned on the purifier at night and (2) the average of the last four hours before I woke up in the morning.

 

Air purifier test laser particle counter

 

Carbon vs. HEPA Results

With the additional charcoal layer, the Cannon particulate effectiveness dropped 1-2%. Thus, charcoal has a very minor negative effect on the Cannon.

DIY Air purifier test carbon filter HEPA

However, the Original DIY had a harder time powering through the extra layer. Its 0.5 micron effectiveness dropped 19%, and 2.5 micron effectiveness dropped 15%.

DIY purifier activated carbon test

Conclusion: Carbon Tips

For people who need carbon (and that may not be everyone), I would recommend adding the carbon to the Cannon, but I would think twice about adding carbon to the Original. One workaround is to have one Original fan running with a HEPA and another running with a carbon filter.

As always, I’m posting the raw data and more details on the test for fellow nerds below.

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Smart Air is a social enterprise that creates simple, no-nonsense air purifiers and provides free education to protect people’s health from the effects of air pollution. We are proud to be the only certified B-Corp dedicated to fighting air pollution.