PHOTOCHEMICAL SMOG DISCOVERED

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PHOTOCHEMICAL SMOG DISCOVERED
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TRANSFORMATION

• The 20th century has been characterised by a
  transition from urban air dominated primary
  pollutants to one where secondary pollutants are
  very important.

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LOS ANGELES EARLY 1940s

• Vanishing streetcars

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LOS ANGELES EARLY 1940s
Eye irritation A 1943 smog Butadiene plant

• Air pollution so bad baseball games not visible
• Japanese gas attacks
• Southern California Gas Companys artificial
  rubber plant - butadiene

http//www.aqmd.gov/news1/Archives/History/marchco
v.html
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LOS ANGELES in FICTION

• Smog appears, but actually not in Chandler till
  1953

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LOS ANGELES mid 1940s

• Post war smog problem still serious
• LA administration suggests it will take a few
  months to solve
• Tucker invited from St Louis hed been
  successful in solving Pittsburghs problems
• The automobile not really a problem no sulfur
  in petrol

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1950 SMOG and LIFE
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LIFE article

• Now industrialisation has caught up with Los
  Angeles to the extent that it has its own special
  brand of smog less grim, but more eye-burning
  chemicals

Good esrly video at http//www.arb.ca.gov/html/br
ochure/history.htm
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A RADICAL IDEA

• Arie J Haagen-Smit biochemist concerned with
  crop damage
• Smelling the air like an organic chemistry lab
• action of sunlight and automotive vapours

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DOMINANCE of the AUTOMOBILE

• Haagen-Smit opposed by auto manufacturers
• Initiated study at Stanford Research Institute
• The now classical understanding derives
• P.A. Leighton, Photochemistry of Air Pollution
  (1961)
• and more fully Heicklen, Westberg and Cohen
  (1969/71)

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NOX PSUEDO-EQUILIBRIUM

• NO O3 ? NO2 O2 (R1)
• NO2 h? ? NO O (R2)
• O O2 ? O3
• NO O3 ? NO2 O2 hv

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NOX PHOTOSTATIONARY STATEEQUILIBRIUM

• R1 - k NO O3 k0.38ppm-1s-1
• R2 -k h? NO2 -JNO2 NO2
• JNO2 photolysis rate, s-1
• JNO2 NO2 k NO O3
• JNO2NO2/k NO O3 1 p

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MODEL VS REALITY
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MODEL VS REALITY
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NOX PSUEDO-EQUILIBRIUM
x

• O3 NO NO2 O2

hv
the nature of X forms a major part of what
controls smog formation

• action of sunlight and automotive vapours

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ROLE OF AUTOMOTIVE VAPOURS

• CH4 OH ? CH3 H2O
• CH3 O2 ? CH3O2
• CH3O2 NO ? CH3O NO2
• CH3O O2 ? HCHO HO2
• HO2 NO ? OH NO2
• CH4 2O2 2NO ? HCHO 2NO2 H2O

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THE RADICAL IDEA

• In a submission to Industrial and Engineering
  Chemistry Haagen-Smit refers to both ozone and
  peroxides
• Significance not quite clear?

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OVERALL CHEMISTRY

• CH3CH3 2O2 2NO ? CH3CHO 2NO2 H2O
• ethane (alkane) acetaldehyde

• action of sunlight and automotive vapours

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ACETALDEHYDE

• CH3CHO OH ? CH3CO H2O
• CH3CO O2 ? CH3COO2
• CH3COO2 NO ? CH3CO2 NO2
• CH3CO2 ? CH3 CO2
• CH3COO2 NO2 ? CH3COO2NO2

Breaking and re-entry
Formation of Peroxyacetylnitrate (PAN)
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EYES, POLLUTION and Optrex

• Treat your eyes to some TLC,
• dusty, smoky atmospheres
• city air pollution
• drying atmosphere of air conditioning Ad in
  London underground

Peroxyacetylnitrate Particle deposition on eyes
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A LONG AND DIFFICULT PROBLEM

• Ozone at Crestline California

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GOING BEYOND LA!

• Liquid fuels
• Mobile sources
• Multiple polluters

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NOT SO MUCH IS AIR POLLUTION GETTING WORSE
ITS CHANGING!
WOOD SMOKE
VOCs, O3
COAL SMOKE
DIESEL SMOKE
LEAD
H2S
SMELLs
TIME