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PHOTOCHEMICAL SMOG DISCOVERED. TRANSFORMATION. The 20 th century has been characterised by a transition from urban air dominated primary pollutants to one where secondary pollutants are very important. . Who Framed Roger Rabbit?. LOS ANGELES EARLY 1940s. Vanishing streetcars.

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Presentation Transcript
transformation
TRANSFORMATION
  • The 20th century has been characterised by a transition from urban air dominated primary pollutants to one where secondary pollutants are very important.
los angeles early 1940s4

Eye irritation

A 1943 smog

Butadiene plant

LOS ANGELES EARLY 1940s
  • Air pollution so bad baseball games not visible
  • Japanese gas attacks
  • Southern California Gas Company’s artificial rubber plant - butadiene

http://www.aqmd.gov/news1/Archives/History/marchcov.html

los angeles in fiction

Raymond Chandler’s Philip Marlowe

LOS ANGELES in FICTION
  • Smog appears, but actually not in Chandler till 1953
los angeles mid 1940s
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 – he’d been successful in solving Pittsburgh’s problems
  • The automobile not really a problem – no sulfur in petrol
life article
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/brochure/history.htm

a radical idea
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”
dominance of the automobile
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)
no x psuedo equilibrium
NO + O3  NO2 + O2 (R1)

NO2 + hν  NO + O (R2)

O + O2  O3

NO + O3  NO2 + O2 + hv

  • “action of sunlight and automotive vapours”
NOX PSUEDO-EQUILIBRIUM
slide12

NOX PHOTOSTATIONARY STATE“EQUILIBRIUM”

R1= - k NOO3 k=0.38ppm-1s-1

R2 = -k h NO2 = -JNO2 NO2

JNO2 photolysis rate, s-1

JNO2 NO2 = k NOO3

JNO2NO2/k NO O3 = 1 = p

no x psuedo equilibrium15
O3 + NO NO2 + O2NOX PSUEDO-EQUILIBRIUM

x

hv

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

  • “action of sunlight and automotive vapours”
role of automotive vapours
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

the radical idea
THE RADICAL IDEA
  • In a submission to Industrial and Engineering Chemistry: Haagen-Smit refers to both ozone and peroxides
  • Significance not quite clear?
overall chemistry

RO2

O3 + NO NO2 + hv

OVERALL CHEMISTRY

CH3CH3 + 2O2 + 2NO  CH3CHO + 2NO2+ H2O

ethane (alkane) acetaldehyde

  • “action of sunlight and automotive vapours”
acetaldehyde
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)

eyes pollution and optrex
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

a long and difficult problem
A LONG AND DIFFICULT PROBLEM

Ozone at Crestline California

going beyond la
GOING BEYOND LA!
  • Liquid fuels
  • Mobile sources
  • Multiple polluters
not so much is air pollution getting worse its changing
NOT SO MUCH IS AIR POLLUTION GETTING WORSE…ITS CHANGING!

WOOD SMOKE

VOCs, O3

COAL SMOKE

DIESEL SMOKE

SMELLs

LEAD

H2S

TIME