Hey it’s Professor Dave, let’s talk about air.
Over the centuries, we’ve come a long way in terms of understanding the composition
of the things around us.
Far beyond categorizing matter as earth, water, air, or fire, we now understand matter on
the atomic and subatomic level.
When it comes to the air around us, our ancestors could feel wind and they knew we needed air
to breathe, but that’s about it.
In this modern era, we know exactly what’s in the air, from its primary constituents,
down to all the dozens of substances present in trace amounts.
We know the structures of these substances, and we know how they interact with our bodies.
And perhaps most miraculously, we know how to purify the air around us.
We know how to pull certain components right out of the air, and we have built some remarkable
devices that enable us to do this.
Let’s get a closer look at air purification as a process, as well as the machines that
achieve this impressive task.
As we mentioned, we have a solid understanding of the composition of air.
So what’s in there, exactly?
By far the most significant component, perhaps surprisingly, is nitrogen.
Around 78 percent of the atmosphere is nitrogen, a diatomic molecule which is relatively inert.
It enters and exits our lungs when we breathe, but generally doesn’t really do anything.
Then, the next most abundant component is oxygen.
That makes up about 21 percent of the atmosphere, and that’s the stuff we actually breathe.
We can’t live for more than a few minutes without oxygen, making this the single most
important substance to our survival.
So we are already up to around 99 percent, which means that only one percent of the air
around us is made up of substances other than nitrogen and oxygen.
Most of that one percent is made up of argon, a monoatomic noble gas.
This is also basically inert, and doesn’t do much.
Then making up the tiny fraction of a percent that remains, we have carbon dioxide, which
is a greenhouse gas.
We also have some more noble gases, helium, neon, and krypton, as well as a little methane,
and some hydrogen, the lightest gas there is.
If we were to dip significantly below a concentration of one part per million, we could list some
more, but let’s just stop here.
So that’s pretty much what we can expect to find in an average sample of our atmosphere.
However, we can certainly expect to find contaminants in the air as well.
These are substances that are not naturally found in the air, but rather make their way
into the air, often as the result of some kind of human activity.
Sometimes this is not a big deal at all, and other times it can be a significant health
risk, so let’s talk about some common air contaminants.
When discussing air contaminants, we can talk about two main types of objects.
First there are volatile organic compounds, abbreviated as VOC’s.
Contrary to popular belief, “volatile” does not have an inherently negative connotation.
It does not mean “bad”.
Volatile just refers to the tendency of a substance to go into the gas phase.
So a highly volatile substance readily goes into the air, which can be dangerous if it
is harmful, because it presents the possibility of breathing it in, as opposed to a substance
that remains a liquid or solid.
Volatile organic compounds tend to include certain ingredients of household cleaning
products, paint, and hygienic products like aerosols and sprays.
The other type of air contaminant would be actual biological matter.
As incredible as it seems, there are all kinds of living organisms and biological particles
floating around in the air.
This includes bacteria and viruses, mold spores, dust mites, allergens like pollen, and lots more.
And of course there is also your run-of-the-mill dust, which is just dirt tracked in from outside,
mixed with soot, hair, and carpet fluff.
Depending on the concentration and the duration of exposure, many of these contaminants we
just listed can have a negative impact on your health, although each by a completely
separate mechanism.
And given that all of these things are far too small to be seen with our eyes, we can’t
exactly pick the bad ones out of the air with some tweezers.
Fortunately, as resourceful as we are, we have learned how to purify the air by mechanical means.
What is an air purifier, and how does it work?
Let’s examine the methods by which a typical air purifier can remove these contaminants,
ensuring that we do not breathe them in.
The simplest way a purifier achieves this is by particle size.
The regular components of the atmosphere are teeny-tiny molecules.
The biological particles we listed, like viruses and mold spores and dust mites, are absolutely
huge in comparison.
So as air continuously passes through a purifier, it is relatively simple to trap large particles
on a filter while all the tiny molecules move through the many tiny pores.
High-efficiency particulate arrestance filters can remove up to 99.97 percent of all particles
larger than 0.3 micrometers in diameter, so most of this biological material will easily
be filtered out as the air passes through.
However, this does not help with small molecules, so for those volatile organic compounds we
mentioned, we will need another strategy.
One technique that is available involves a material called activated carbon.
This is where we take chunks of carbon, usually in the form of charcoal, and expose it to
high concentrations of oxygen.
This results in the formation of an incredible number of pores on the surface of the material,
and when air passes through this material, small molecules can get adsorbed into the pores.
This is a common technique for removing pollutants from the air, and it specifically works on
small molecules.
So devices that use these two techniques in tandem can be quite effective in eliminating
a wide array of contaminants.
But it doesn’t stop there.
These basic techniques have been innovated substantially, and technology that has previously
only been available in industrial products is now available in consumer products meant
for home use.
An example of such a product is the EnviroKlenz air purification system.
Let’s see how this product approaches the elimination of the aforementioned contaminants.
To start, this system utilizes a two-stage filtration process, with HEPA filtration for
large particles, and an adsorptive surface for small molecules.
For an adsorptive surface, the EnviroKlenz utilizes a blend of high surface area metal oxides.
This material is highly reactive, capable of what is referred to as destructive adsorption,
by which it traps and destroys microbes like mold spores.
Once adsorbed, a UVC lamp continuously shines ultraviolet light on any pathogens, which
destroys their DNA, thus rendering them dead or inactivated.
This adsorptive material is simultaneously effective against volatile organic compounds,
and adsorbs them irreversibly, when oxygen, nitrogen, and sulfur atoms from a variety
of functional groups directly interact with the metal atoms in the oxide, which act as
a Lewis acid.
This makes the material much more effective than activated carbon technology, which does
not offer this type of chemisorption.
To get more specific, this material is effective with formaldehyde, fragrances, pesticides,
tobacco smoke, and many other types of small molecules.
So essentially, the material in this filtration system is both more multifaceted and more
powerful than pre-existing consumer technology.
In addition, this system involves no release of byproducts into the atmosphere, so it is
also supremely environmentally friendly.
Contaminants remain bound to a cartridge that is replaced every six months, and all the
air in a room can be exchanged several times per hour as it moves through the system, so
the action is just as rapid as it is effective.
It is absolutely incredible to think of how far we have come in the past hundred years or so.
At the turn of the 20th century, we barely even knew that atoms and molecules existed,
and now our understanding of the molecular world is so sophisticated, that we have an
intimate understanding of the composition of the invisible air around us, and can even
manipulate that composition at will, removing unwanted pathogens and odors, thereby making
sure it is safe and pleasant to breathe.
The fast-paced technological innovation of the 21st century is no less impressive, as
the technology previously found in expensive industrial products tend to get implemented
in affordable consumer products within a decade.
With a little ingenuity and a dash of optimism, we can ensure that everyone will get to enjoy
the purest air in the history of our planet for millenia to come.