The wildly complex anatomy of a sneaker Angel Chang
Australians call them “runners."
The British know them as “trainers."
Americans refer to them as “tennis shoes”
or “sneakers."
Whatever you call them,
these rubber-soled, casual shoes
are worn by billions of people
around the world.
Originally invented
in the late 19th century,
these simple canvas and rubber creations
have changed a lot
since they first hit the pavement.
Today, sneaker consumption
is at an all-time high.
No country buys more sneakers
than the United States,
where people purchase 3 pairs
a year on average.
To meet this demand, roughly 23 billion
shoes are produced each year,
mostly in factories
across China and Southeast Asia.
But making shoes has become
more complicated, more labor-intensive,
and in some ways, more dangerous,
for the workers involved
and for our planet.
Shoe manufacturing
accounts for roughly one-fifth
of the fashion industry’s
carbon emissions.
Sneakers alone generate 313 million
metric tons of carbon dioxide every year,
which is equivalent to the annual
emissions of 66 million cars.
To better understand
your shoe’s carbon footprint,
let’s dive into the anatomy of a sneaker.
For starters, the heel, insole,
midsole, and upper layer
are usually made from synthetic textiles
like polyester, nylon, latex,
and polyurethane.
Mining the fossil fuels that make up these
materials emits tons of greenhouse gases.
And processing those raw ingredients
into synthetic textiles
also uses a lot of energy,
further compounding that pollution.
Some sneaker tops are made from
natural sources like leather,
but tanning this material
relies on chromium;
a carcinogenic chemical that can damage
freshwater ecosystems.
The outer soles of most shoes
are made of rubber
that’s gone through a process
called vulcanization.
This technique adds sulfur to superheated
raw rubber to create a material
that’s both elastic and sturdy.
Until recently, sneakers used
natural rubber for this process.
But today, most outer soles are made
with a synthetic blend of natural rubber
and byproducts from coal and oil.
Producing these materials accounts
for 20% of a sneaker’s carbon footprint.
But more than two-thirds of the shoe’s
carbon impact comes from the next step:
manufacturing.
A typical sneaker is comprised
of 65 discrete parts,
each of which is produced
by specialized machinery.
This means it’s cheaper for factories
to mass-produce each piece separately
rather than manufacturing
every part under one roof.
But the transportation
required to ship these pieces
to one assembly plant emits even more CO2.
Once the components arrive
at the assembly line,
they undergo cutting, pouring, melting,
baking, cooling, and gluing,
before the final products
can be stitched together.
The assembly of a typical sneaker
requires more than 360 steps,
and accounts for the remaining 20%
of a sneaker’s environmental impact.
The dispersion of factories fuels
another problem as well: labor abuse.
Most brands don’t own
or operate their factories,
so the plants they work with
are in countries
with little to no worker protection laws.
As a result, many laborers
earn below the living wage,
and are exposed to harmful chemicals,
like toxic glue fumes.
When manufacturing is complete,
the shoes are packaged and transported
to stores around the globe.
For many, these shoes could last years.
But for someone running 20 miles a week,
a pair of running shoes will start
wearing out after roughly 6 months.
Since the shoes are made of
so many different materials,
they’re almost impossible to break down
into recyclable components.
20% of these shoes are incinerated,
while the rest are tossed into landfills
where they can take up to 1,000 years
to degrade.
So, how can we balance
our love of sneakers
with the need for sustainability?
First, designers should streamline
design elements
and focus on eco-friendly materials.
Factories need to develop energy efficient
manufacturing processes
that consolidate steps and sneaker parts.
And consumers should support
companies using clean energy
and ethical manufacturing processes.
We can also buy fewer shoes,
wear them for longer,
and donate those we no longer need.
So no matter what your style, we can all
take steps towards a sustainable future.