EOH 468: Air Pollution and
Health
Dr. Peter Bellin, CIH, Ph.D.
Spring 2008
Introduction
•
•
•
•
Syllabus posted on-line.
Lecture notes.
Texts: recommend they be purchased.
Try to do readings, draft answers to
questions.
History of Air Pollution
• Ancient times, not a significant problem
• Burning sea coal in 1300’s
• Nineteenth century: literature references to
polluted air
• 1892: 1000 die in London
• 1930: Meuse Valley, Belgium, 50 dead.
• 1943: Los Angeles incident
1
History of Air Pollution
• 1948: Los Angeles APCD is established
• 1948: Donora, PA – 20 dead, thousands
made ill. (Essay by Berton Roueche)
• 1952: London ‘Killer Fog’, over 4000 dead.
• 1953: Smog in NYC kills between 170 and
260 people.
• 1963: First US Federal Clean Air Act.
London 1952
London 1952
2
London 1952
London 1952
London 1952
3
Donora, PA at noon
Thin blanket of air
The moon through atmosphere
4
Smog in Los Angeles
History of Air Pollution
• Video on the history of air pollution
– California Air Resources Board video
– http://www.aqmd.gov/pubinfo/video/clrcaskies.htm
Structure of the Atmosphere
EOH 468
Spring 2008
Week 2
5
Structure of Atmosphere
• Evolution of the Atmosphere
– Current composition
•
•
•
•
•
Layers of the atmosphere
Temperature profile
Ozone profile
Weather systems
Pollution distribution
Evolution of the Atmosphere
• Original atmosphere had no oxygen.
• Any oxygen created was absorbed by
earth (iron, etc.)
• Carbon dioxide levels were high.
• Chemical reactions created water
– 3 H2 + CO2 → CH4 + H2O
– H2 + CO2 → CO + H2O
• Water created oceans, sink for CO2
Evolution of the Atmosphere
• Nitrogen was present, but relatively inert, and
built up to high concentration.
– Nitrogen cycle helps maintain balance.
• Early photosynthesis resulted in more free
oxygen (once minerals were oxidized)
– CO2 + H2O → CH2O + O2
• By 400 million years ago, current levels of
oxygen were reached.
• By about 400 million years ago, current level of
carbon dioxide was reached.
6
Composition of Atmosphere
Nitrogen
78.08400%
Oxygen
20.94800%
Argon
0.93400%
Water Vapor
1.50000%
Carbon Dioxide
0.03700%
Neon
0.00182%
Ozone
0.00070%
Helium
0.00052%
Methane
0.00017%
Krypton
0.00011%
Hydrogen
0.00005%
Xenon
0.00001%
Nitrous Oxide
0.00003%
Carbon Monoxide
0.00001%
Ozone (Troposphere)
0.00000%
Oxygen,
20.9%
Other,
2.5%
Nitrogen,
78.1%
Layers of the Atmosphere
• Troposphere
• Stratosphere
• Ionosphere
http://des.memphis.edu/lurbano/G
eog1010/Fall05/chapter_03/chapt
er 03 html
7
http://des.memphis.edu/lurbano/G
eog1010/Fall05/chapter_03/chapt
er 03 html
8
Ozone Depletion
• Related to release of chlorofluorocarbons
• Chlorine catalyzes depletion of ozone
• Strong effect over Antarctica
– Related to weather patterns there.
• Visit here for explanation:
• http://www.atm.ch.cam.ac.uk/tour/index.html
Ozone Depletion
• Chemistry on polar stratospheric clouds
– HCL + ClONO2 → HNO3 + Cl2
– ClONO2 + H2O → HNO3 + HOCl
– HCl + HOCl → H2O + Cl2
– N2O5 + HCl → HNO3 + ClONO
– N2O5 + H2O → 2 HNO3
• The net effect is to build up chlorine and
nitric acid.
9
Ozone Depletion
• The nitric acid is not active in reducing chlorine
oxide in the atmosphere.
• Chlorine gas is easily split into chlorine atoms.
• ClO + ClO + M → Cl2O2 + M
• Cl2O2 + hv → Cl + ClO2
• ClO2 + M → Cl + O2 + M
• 2 x (Cl + O3) → 2 x (ClO + O2)
• Net: 2 O3 → 3 O2
• This occurs at very low temperatures.
Ozone Depletion
• Arctic region also experiences ozone
depletion, but this reaction predominates:
• ClO + BrO → Br + Cl + O2
• Cl + O3 → ClO + O2
• Br + O3 → BrO + O2
• Net: 2 O3 → 3 O2
10
Ozone Depletion
Ozone Depletion
Ozone Depletion
11
Temperature Profile
• Troposphere profile
– Lapse rate
– Temperature inversion
– Mixing cap
Troposphere Temperature Profile
12
Troposphere Temperature Profile
http://daphne.palomar.edu/calenvironment/smog.htm
Troposphere Temperature Profile
Cyclones and anticyclones
• Deflection of wind causes air to flow
in a roughly circular pattern
• This circular flow may be clockwise
(anticyclonic) or counterclockwise
(cyclonic)
13
Cyclones and anticyclones
• On weather maps isobars describe
circulation cells of high and low
pressure
• Air flows parallel to isobars in a
curved path
– Associated winds called gradient winds
– Caused by the combined effects of pressure
gradiant force (PGF) and coriolis effect
Cyclones and anticyclones
• In northern hemisphere air flow is
counterclockwise in low pressure
systems and clockwise in high
pressure systems
• This pattern is just the opposite in the
southern hemisphere
High and low pressure systems
14
Low pressure systems
• Air flows inward(convergence) and
upward and outward(divergence)
• Have cyclonic flows in the northern
hemisphere
• Represent very unstable air masses
• Characterized by cloudiness,
precipitation, storminess
High pressure systems
• Air flows downward
(subsidence) and outward
(divergence)
• Have anticyclonic flows in the
northern hemisphere
High pressure systems
• As air subsides it compresses air
beneath it causing a warm air layer to
form
• Characterized by clear skies, no
precipitation, low wind speeds and
stability
15
High and low pressure systems
• Cross-sectional diameters of 1001000 km
• Commonly are migratory
• In temperate latitudes affected by
tropical and polar air
• Move from east to west
• Have a life span of 1-2 weeks
Global air circulation
• Best described by a three-zone
model
• Air at the equator flows pole-ward and
descends at about 30o N & S latitude
flowing along the surface back to the
equator
Global air circulation
• Cold air flowing along the surface
from the poles toward the equator is
warmed and ascends toward poles
• These flows are Hadley-type
16
Three-zone model
Three-zone model
• Air in middle latitudes forms only
weak north-south circulation patterns
because of the intrusion of tropical
and polar air
• Jet steams form at discontinuities
between zones
Jet streams
• Systems of fast moving air in upper
troposphere
• Produced as a result of strong
pressure differences at surface that
produce strong pressure gradients
aloft
• Polar jet stream forms over middle
latitudes associated with polar front
17
Jet streams
• North polar jet stream meanders with
movement of polar front
– In winter may extend as far south as 30o N
– In summer average position is 50o N
– Because of this migration described as midlatitude jet stream
Jet streams
• Semi-permanent jet stream forms
over tropics in winter
– Slower than polar jet stream
– Centered at about 25o N
Jet Streams
18
Jet Streams
• Important because they influence
surface air flow patterns and weather
– On acceleration they cause divergence aloft
that promotes converge near the surface and
cyclonic motion
– Supply energy to storm systems and direct
their path
– Also cause convergence aloft which
intensifies high pressure systems
Weather Systems
• Weather dynamics affects air pollution
• Jet Streams
• http://www.pbs.org/wgbh/nova/vanished/je
tstream.html#
Pollution Distribution
• Intensity of air pollution varies
• Interior areas in LA basin
• http://www.arb.ca.gov/knowzone/basin/bas
in.swf
• Air Now site (current conditions)
– http://www.airnow.gov/
19
Pollution Distribution
Pollution Distribution
Pollution Distribution
20
Pollution Distribution
Pollution Distribution
Pollution Distribution
21
Pollution Distribution
22