How to Build the Ultimate Air Purifier

In 2018 we realized the importance of air quality and began research and development with the goal of building the best air purifier that exists.  We first did extensive research on what types of units are currently available and what air purification technologies are out there.  It turns out there are really only 5 air purification technologies; mechanical/HEPA filtration, activated carbon, UV, ionization, and ozone generation.  Any other fancy "new technologies" that companies claim to have are really just a variation on the five above.

Since our mission is "to improve human performance, health, and quality of life by providing access to clean air," we quickly ruled out ozone generation because ozone causes all kinds of respiratory issues.  Ionization was out of the question because ionizers work on the principle of statically charging particles in the air so that they eventually find a surface to stick to.  The surfaces the particles stick to end up being walls, furniture, and your lungs.  So in principle they basically remove pollutants from the air by putting them all over your home and in your body.  In practice, studies have determined that ionizers are largely ineffective at reducing particulate levels in the air.

We were initially curious about using UV to kill germs in the air.  While it is true that a specific high energy frequency of UV radiation called UVC can damage the DNA of microorganisms, we learned that in an air purifier where the air is moving by the UVC lamp so quickly that there is not enough exposure time to effect the bacteria and viruses.  Also, a byproduct of UVC is the production of ozone, which as we found, is bad for human health.  UVC radiation must be completely isolated from humans because it can cause severe skin burns and eye damage.  For these health risks and lack of real world results, we determined not to use UV.

Once we ruled out the fancier technologies as being ineffective and unhealthy, we began exploring the elemental basic technology of mechanical filtration.  This is where air is pushed or pulled across an air filter that acts like a strainer to pull out particulates from the air.  Mechanical filtration produces no harmful byproducts and is extremely simple and effective.  The only challenge is that in order to effectively clean the air, the unit's filters must be high "efficiency" AND the unit must move a lot of air.

A filter's efficiency describes the percentage of particulates of a certain size that the filter removes from the air.  A higher efficiency filter means that it will remove more small particles.  So in order to remove the most microscopic particles we should just use a very high efficiency sheet of filter material right?  In general, the higher the efficiency of the filter material, the harder it is to move air through it.  So in order to move a lot of air through a high efficiency filter material, we need to use a big fan that draws a lot of power and makes a lot of noise.  That was the trade off we were faced with.  Should we: 1) deliver air that's not that clean? 2) deliver a small amount of very clean air? or 3) deliver a large amount of very clean air and make a lot of noise and use a lot of electricity?

We didn't want to make any compromises in pursuit of delivering lots of very clean air quietly with low power, so we designed air filters that would allow us to accomplish this before we even had a design for the unit itself.  By using an optimized pleated design we were able to compress a very large surface area of high efficiency filter material into a small space that allows for greater airflow.  Even though it's possible to make the filter material into very efficient shapes, maximum performance still is not possible with very small filters, such as the ones found in a lot of other units.  That's why our air filters are so big.  We made two of these filters for our unit.  One of these filters is a HEPA filter, which has been tested to remove more than 99.97% of all particles down to 0.1 microns.  Together these filters would allow our air purifier to remove dust, pollen, mold spores, dust mites, pet dander, smoke, bacteria, viruses, and even radioactive fallout.

But we learned that volatile organic compounds (VOCs) and chemicals that cause odors are common indoor pollutants that are bad for people's health, and these mechanical filters alone couldn't remove them because VOCs are the size of molecules.  That's where another elemental air filtration technology comes in.  Activated carbon is essentially carbon that has been processed to have the maximum surface area of microscopic pores in it.  These pores are the perfect size to capture VOCs and odors to remove them from the air.

But we didn't want to use just a light dusting of carbon like other air purifier companies do just to add it to the features list.  No, we wanted our activated carbon to make a meaningful difference in the quality of the air.  So we designed a custom carbon filter that has corrugations that contain over 3 pounds of granular activated carbon.

Once we had our three filters designed, we designed the rest of the unit around them.  We gave it a modern minimalist aesthetic and deliberately avoided using complicated controls, menus, schedules, wifi, and apps.  We made the control as easy as possible to use.  Turn it on, set your fan speed, and that's it!  When it's time to change the filters the unit will tell you with a light.  It was important that it's easy to change the filters, so we made a simple latching door that easily comes off to give access to all 3 filters at once.  We decided to use an EC fan made in Germany to ensure long term reliability, and our fan uses up to 85% less electricity than the AC fans in most other units.

The end result of our quest to build the safest most effective air cleaning machine is Aspen.  Aspen is easy to use, 100% safe, delivers a high volume of clean air quietly, and has the highest efficiency air filtration system of any air purifier that we're aware of.  Aspen can make a positive difference in your life by providing access to truly clean air.