The air around us is full of all sorts of particles bouncing around and riding the breeze.
If those particles make it into our lungs, they can wreak all sorts of havoc on our bodies.
But in order to get there, they have to make it through a harrowing gauntlet of obstacles that,
thanks to evolution, exists to protect us.
On their journey to the deepest parts of the lungs, the particles face
three major challenges. The first is the nose hair forest, which is packed with coarse, sticky hairs.
Many particles can skirt this defense easily, but it's hard for the biggest airborne particles, like
sand or large pollen grains, to make it through the tightly-packed bristles without getting stuck.
Particles that survive the forest are not out of the woods yet - they must then pass
through the Caverns of Nasopharynx, where three bony structures swirl the air into a vortex.
Mid-size particles have enough mass that once they enter the cavern, the vortex centrifuges them
directly into the cave’s sticky, mucus-covered walls...ending their journey. Still, some of
the smaller particles sneak through by riding the turbulent air current to the other side.
The particles that weather the vortex still have one more challenge: the deep, dark Bronchial
Tunnels, which are a labyrinth of branching, ever-narrowing passageways between the windpipe
and the lungs. Because super-small particles are light enough to ricochet off air molecules,
lots of them end up bouncing right into the glue-like tunnel walls. To survive, particles
have to be small enough to have made it this far, but big enough that bouncing off of air molecules
doesn't send them into the walls. This last obstacle - along with the others before it - is a
tough challenge, which means that only rarely does anything survive the gauntlet, pass from our lungs
to the bloodstream, and wreak some serious havok. For thousands of years, this gauntlet filtered out
most airborne stuff, like sand, dust, and smoke, with only the occasional problematic particle
sneaking through. But now - as we drive cars, burn coal for power, and cook indoors - more
particles than ever fill the air and crowd into the gauntlet, causing two problems. First,
all these particles clog up the obstacles’ sticky surfaces, making them less effective.
Second, lots of today’s airborne particles happen to be a problematic size:
they’re small enough to pass through the nose hair forest and Caverns of Nasopharynx, but big
enough to avoid getting captured in the Bronchial tunnels. From there, these problematically-sized
particles follow the airflow to the lungs, cross into the bloodstream, and then hitch
a ride to pretty much any organ in the body. Once they arrive, they can cause all sorts of damage,
like cancer, cardiovascular diseases, and strokes. Fortunately, just as we humans have evolved
complex respiratory gauntlets, we’ve also evolved complex brains. And while these clever brains
are admittedly behind all that burning we do, they can also help us cope with this barrage
of airborne particles. We can measure air quality to help us steer clear of times and
places where pollution is really bad, keeping particles from clogging the gauntlet. And we
can add additional obstacles to the gauntlet, by using air filters in our homes and offices,
or even adding filters directly to our faces. Long-term, we want to avoid creating all those
gauntlet-clogging particles in the first place. After all, this is a life or breath situation.
Many of the ways we can avoid creating problematic particles are also ways we
can reduce putting more carbon into the air. And thanks to Wren, which sponsored this video,
all I have to do is answer a few small questions about my habits and lifestyle on Wren’s website,
and it generates a personalized report estimating how much carbon my activities release into the
atmosphere. Wren not only gives suggestions about how to reduce my personal carbon emissions,
it also allows me to offset the carbon that I do release by making a monthly contribution
towards projects like tree planting and forest protection. And the first hundred of you who sign
up using the link in the description, Wren will plant 10 extra trees per person. Thanks Wren!