SmogSmog

Los Angeles

Pittsburgh Dallas

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

Pittsburgh todayPittsburgh today

2009

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

8 ½ pairs of electrons

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

NONO2 2 rears its head on hot daysrears its head on hot days

As the temperature climbs into the 100oF range, a reddish brown haze appears in the sky if NO2 is present.