- Have you ever spent a day frolicking
down the avenues of a favorite major city?
Taking in the sights and the smells
and then blowing your nose?
Did you discover that your nasal passages
hawked up a plug of soot colored snot?
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Big deal, you may think.
This stuff isn't a
living, breathing organism
that'll take over my body and
putrefy my internal organs.
True, but the grime coating
cities isn't passive.
It's belching back at
us, and it isn't pretty.
James Donaldson a chemistry professor
at the University of Toronto,
led his research team to conclude that
when sunlight directly hits grime
it can re-release Nitrogen Oxide gasses
back into the urban atmosphere.
Specifically Nitrogen
Dioxide and Nitrogen Acid.
That's a big deal because Nitrogen Acid,
in particular is known to
be a key element in smog.
And the more smog, the more
pollution is held hostage
in a cloud looming over a city
and affecting its air quality.
Donaldson conducted tests in the lab
and then took his research into the field
in Liepzig, Germany.
Where he placed two large
trays of glass beads
on a tower high above the city.
For six weeks each tray
listed the same airflow.
And both were equally
filthy from pollution,
but only one tray was placed in the sun.
The team saw the same result in the field
that they observed in the lab.
When sediment pollution
is exposed to sunlight,
it causes the loss of
Nitrogen Oxide gasses.
The burping, if you will, of
the grime back into the city.
This finding is important
because it shows a direct
cause and effect between
existing pollution
and the environment.
Moreover with the atmosphere heating up,
we'll be subject to more
and more Danger Days.
These are rare days when humidity and heat
combine to create a heat index
of 105 degrees Fahrenheit, or higher.
And besides making the
outdoors sort of unbearable
and miserable, these conditions
are extremely hazardous
for people sensitive to heat,
like children and the elderly,
as well as those with
respiratory ailments,
or heart conditions.
According to Climate Central
since 1950 only 12 U.S. cities
averaged more than one Danger Day a year.
But, by 2030 they predict that 85 cities,
home to a third of the population,
will experience 20 Danger Days a year.
Yeah, 2030 is going to be
breathtaking, literally.
All right, let's all
take a collective breath.
And if you found this video
a breath of fresh air,
make sure to like us here,
subscribe and check back later
for more How Stuff Works Now.
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