Are Carbon Air Filters Safe

Companies sell activated carbon filters (also called "charcoal filters") to remove chemicals similar formaldehyde and benzene, but does carbon actually work? The Smart Air lab put real-world carbon filters to the test.

Who Needs Carbon Filters Anyway?

I wrote early on that my number one concern in People's republic of china is particulate pollution. It's on so many people'south minds that nowadays even the guy I buy kebabs from knows the discussion "PM2.5."

HEPAs practise an amazing chore at removing particulates, but particulates aren't everything. Gases like volatile organic compounds (VOCs) are and so pocket-size that they slip through HEPAs. "VOC" is a large category, including things like benzene and formaldehyde. VOCs can cause cancer, throat irritation, dizziness, and other not-fun side effects.

When I published the instructions for how to build your own purifier, I wasn't comfortable recommending activated carbon because I hadn't tested information technology, and I didn't want to but trust what the big filter companies say. So this year, I fix out on a journey to exam whether carbon really works.

Put to The Test: Does Carbon Really Piece of work?

I soon learned that gas testing is not easy. First off, "harmful gases" is not a natural category. You can purchase a particle counter that will detect all particles of a certain size, but there is no detector that volition notice all gases. Instead, yous demand 1 for each type of gas, and that is not cheap.

In this case, my scientific marvel price me $3,542 for this Industrial Scientific Ibrid MX6. It detects VOCs, carbon monoxide, sulfur dioxide, hydrogen sulfide, and nitrogen dioxide. It uses a photo-ionization detector to measure VOCs from 0-2,000 parts per million with a resolution of .1.

Side by side, I needed a source of gas pollution. Interestingly enough, my apartment didn't take enough VOCs to register on the MX6–nor did viii other Beijing apartments I tested. (That speaks to whether purifier companies should scare people into thinking that everyone needs carbon.)

Because I didn't have detectable VOCs in my abode, I had to get out and find VOCs to pump into my room. I chose cigarettes considering they are known to emit VOCs like benzene and formaldehyde.

In each test, I burned 3 Marlboro cigarettes in an enclosed 3.78 m2 porch. At the same time, I ran the Cannon on high for v tests with a blended carbon filter on the front:

I ran four control tests with a fan but no filter. That style the room yet has air flow, but no carbon. The cigarettes burned out after almost 15 minutes, and I left the fans on for some other thirty minutes.

Results: Does Carbon Really Work?

Looking at the Cannon + carbon alone after the cigarette extinguished, the VOCs dropped. Here is the information from ane test:

Simply peradventure the VOCs would accept just dissipated on their own? From there, we tin zoom out to include the fourth dimension the cigarette was burning and the test where we had just a fan (no filter). From there, it becomes clearer that the carbon was removing VOCs to a higher place and beyond merely having a fan on.

Averaging across all of the tests, the VOCs reached a maximum of virtually 1 ppm while the carbon was on. Without the carbon, VOCs reached 1.five ppm.

Later the cigarette burned out, the Cannon cleared the air of VOCs in merely over 15 minutes on boilerplate. Without carbon, the air still had VOCs later thirty minutes.

Averaging over all of the tests, the carbon removed 38% of VOCs by the time the cigarettes burned out compared to the fan-only status. The Cannon removed 68% afterward another v minutes and 100% by twenty minutes after the cigarettes burned out.

Lesser Line: Exercise Carbon Filters Work?

Test data showed that activated carbon filters effectively removed VOC gases compared to just a fan alone.

Smart Air

Thus, I've decided these filters are ready for game time. I've started shipping these tested carbon filters via our website and Taobao.

Does Everyone Need Carbon?

Does carbon really work? Yeah. But does anybody need carbon? Purifier companies take a financial incentive to convince people to purchase carbon filters. They brand more money if they can scare people into buying carbon. But does everyone need carbon?

I don't want to scare people into buying carbon. Why? In near homes, my MX6 detected zero VOCs. I only found VOCs in homes that had an obvious source of pollution such equally remodeling or fume. And in all of the places where the MX6 detected VOCs, I was able to notice a chemical smell. That makes sense, since lots of VOCs have noticeable smells, like benzene, toluene, and formaldehyde.

Now, I don't want to say that VOCs are never a problem. Photo ionization detectors like the MX6 are not the almost sensitive test type out there. I bet I'd pick upward minor amounts of VOCs if I sent air samples to a laboratory.

However, scientists accept used fancier methods and plant similar results. For example, scientists in Hong Kong tested homes and plant that about not-smoking homes did not have un-condom levels of VOCs. We need more than tests like this to be certain.

For now, I will non be using carbon in my home, but I call up it is right for people whose homes have:

1. Recent remodeling

2. Recent painting

3. Smoking

4. Odors

5. Nearby sources of gas pollutants (such as living virtually a mill)

6. Symptoms such as inflammation and asthma

Practise I However Demand The HEPA?

Yes. Carbon captures gas pollutants, not particulate pollution. I wouldn't accept fifty-fifty tested this, simply Anna accidentally forgot to attach the HEPA and unknowingly ran a regular particulate room test with carbon merely.

The results weren't pretty–far below the 95% reduction with the added HEPA. Thus, I do non recommend using carbon only.

As always, I'thou posting the raw data and more details on the methods for fellow nerds beneath.

Does Carbon Really Work: Open up Methods

During the gas examination, all of the doors and windows were closed. Because the exam took place in an enclosed porch, there were several windows, which means the room was less well sealed than an interior room.

During the test, I burned three Marlboro cigarettes pointing straight up in an ash tray on the floor. The gas detector was on a small ledge at simply above waist top, simply a few anxiety laterally abroad from the cigarettes. The purifier was placed a couple feet from the cigarettes in the center of the porch with the air stream pointing upward.

Limitations

Burning three cigarettes in a small room is extreme. With the exception of airport smoking lounges, few places will have this much smoke in i identify. However, the examination does demonstrate that carbon reduces VOCs.

Many people have asked me how long carbon filters last. Unfortunately I don't have a good answer to that. The carbon filter I used was still effective afterwards several of these powerful smoke tests, which should be far more VOCs than a normal person would face, merely I cannot say more than that.

VOC Info: The PID lamp has an eV rating of 10.6. eV ratings determine what types of VOCs PID machines tin can detect. With a rating 10.6 eV, this machine was probably reliably detecting benzene, which has an ionization potential of 9.25 and perhaps toluene, which is at eight.82.

This PID lamp is not designed to detect formaldehyde, which has an ionization potential of 10.88. Withal, I later conducted tests with formaldehyde samples and constitute that the MX6 could detect information technology, and an engineer at Industrial Scientific told me he thought information technology was plausible that the machine would pick up on formaldehyde, although not 100% reliably.

Detector Info

The MX6 came with a pump to draw in air (as opposed to versions that passively sample air). During the test, the MX6 had a filter on designed to prevent particles from entering the motorcar. I zeroed the machine if necessary before the test.

Early on Tests

As I started doing the tests, I was still figuring out how to exercise the tests–information technology seems simple when you look at the results, just tests like this are not piece of cake! For the first three control tests, I had non yet decided to let the MX6 run for xxx minutes after the cigarettes burned out, and so information is limited for those three occasions. However, the conclusions are similar with those three tests excluded.

Command Status

In the control condition, I used a Honeywell fan on the depression setting to estimate the air flow of a Cannon on high with a filter on it. The indicate is that filters lower the air flow, then the Honeywell may exist a better approximation of the amount of air flow during the experimental condition.

In addition, I ran tests with an IQ Air Health Pro Plus (i) with the filters removed and (2) with the pre-filter only as additional control tests. The results were similar to the Honeywell fan-only tests. I'll use the IQ Air tests as the control condition in tests of the IQ Air's ability to remove VOCs in the future.

Gas Test Information

The table beneath summarizes the gas tests. Considering the raw data file is large, I'm making information technology available equally a download from this file: Cannon VOC Tests

Data: Carbon-simply exam

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