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Causes of SmogCauses of Smog
Smog is caused by:Smog is caused by:
Smoke ParticlesSmoke Particles
OzoneOzone
NONO22
Many othersMany others
PittsburghPittsburgh
Has always been known as a smoky townHas always been known as a smoky town
Still beats L.A and Dallas for air pollutionStill beats L.A and Dallas for air pollution
PittsburghPittsburgh
Had many steel mills and made widespread Had many steel mills and made widespread use of cheap West Virgina coaluse of cheap West Virgina coal
1944
PittsburghPittsburgh
The hills trapped the smog and sometimes The hills trapped the smog and sometimes turned day into night.turned day into night.
8:40 AM , 1932 11:00 AM 1949
Donora, Pa. Donora, Pa. Worst air pollution disaster in the United StatesWorst air pollution disaster in the United StatesKiller smog on Halloween 1948Killer smog on Halloween 1948Started the clean air movementStarted the clean air movement
Donora, 1946
US Steel open hearth furnace, Donora, Pa.
Donora, Pa.Donora, Pa.
The Largest Zinc Smelting plant in the world, and a U.S. Steel The Largest Zinc Smelting plant in the world, and a U.S. Steel plant tooplant tooAll in the Monongahela River valley, surrounded by hillsAll in the Monongahela River valley, surrounded by hills
The Donora DisasterThe Donora DisasterOctober 27, 1948October 27, 1948
Thick smoky fog lasted Thick smoky fog lasted for 5 daysfor 5 days
Couldn’t see Couldn’t see Halloween paradeHalloween parade
70 people died in a 70 people died in a weekweek
6,000 were medically 6,000 were medically treated because they treated because they couldn’t breathecouldn’t breathe
Population was only Population was only 14,00014,000
Only 2 hospitals and 8 Only 2 hospitals and 8 doctors in towndoctors in town
COCO2, 2, NONO2, 2, SOSO22, and F, and F22 were all to blamewere all to blame
Donora, Pa.Donora, Pa.Donora is Donora is remembered remembered as a key event as a key event that inspired that inspired federal air federal air pollution pollution legislation in legislation in the 1960s and the 1960s and 1970s. 1970s. It contributed It contributed indirectly to indirectly to the the establishment establishment of the U.S. of the U.S. Environmental Environmental Protection Protection Agency in Agency in 1970. 1970.
Regulations were put into place and by 1955 the Pittsburgh area had Regulations were put into place and by 1955 the Pittsburgh area had cleaned up emissions by 97 percent. cleaned up emissions by 97 percent.
In 1963, the United States Congress passed the In 1963, the United States Congress passed the Clean Air Act.Clean Air Act.
Donora, Noon, 1948
PittsburghPittsburgh
Local regulations and the Clean Air Act of Local regulations and the Clean Air Act of 1963 has had a visible impact1963 has had a visible impact
1954 - Liberty Tunnel – vs 1965
What makes smog so bad?What makes smog so bad?Smog consists of NOX (NOSmog consists of NOX (NO22) and Ozone (O) and Ozone (O33))It is extremely toxic and corrosive. It is extremely toxic and corrosive.
Virtually all the plant life was dead for a ½ mile around Donora even before 1948.
What makes smog so bad?What makes smog so bad?Repeated exposure may permanently Repeated exposure may permanently damage lungs or aggravate respiratory damage lungs or aggravate respiratory infections. infections. It reduces lung function or aggravates It reduces lung function or aggravates existing respiratory conditions such as existing respiratory conditions such as asthma, emphysema or bronchitis. asthma, emphysema or bronchitis. It causes chest pain, coughing, throat It causes chest pain, coughing, throat irritation or congestion. irritation or congestion.
Let’s look at NOLet’s look at NO22
Why is it so bad?Why is it so bad?
Why is it so reactive?Why is it so reactive?
How many valence electrons does it How many valence electrons does it have?have?
5 + 2(6) = 17 electrons5 + 2(6) = 17 electrons
It’s an odd numberIt’s an odd number
8 pairs and one more electron8 pairs and one more electron
Lewis Structure of NOLewis Structure of NO22
Extra stability added due to resonance
But still not the most stable compound around
Bent molecular structure
Formation of NFormation of N22OO44
Sometimes two NO2 molecules combine to form N2O4
The Nitrogen has a full octet now. It makes the molecule more stable, but it must not be too strong, because it takes very little temperature to break it.
A constantly shifting balance or A constantly shifting balance or equilibrium reactionequilibrium reaction
As the weather temperature climbs into the 100oF range, the N2O4 breaks back apart into NO2.
N2O4 NO2
Clear gas
Cold days
Less reactive
Full octet
Red-Brown Gas
Hot Days
More reactive
Odd # electrons