Los Angeles Air Quality
• During hot months, Los Angeles
occasionally suffers from temperature
inversion
• Under normal conditions the air cools
with distance from earth’s surface
• Emissions normally dissipates into the
atmosphere, rising through progressively
cooler air
Temperature Inversion
• Sometimes layer of cooler air from
ocean slides under layer of warmer
air
• Under these conditions, polluted air
trapped by layer warm air
• Instead of spreading upward,
polluted air spreads laterally
Temperature Inversion
• Ocean breeze doesn’t allow westward
expansion
• San Gabriel Mountains trap air; causing
pollution accumulate in foothills
• Most famous case of temperature
inversion is the 1952 Great Smog in
London
LA’s air quality began to decline as its
population grew
Year
1910
1930
1950
1970
2010
LA County
population
504,131
2,208,492
4,151,687
7,041,980
9,818,605
• Problems of smog became
prominent in 1940
• Episodes occurred in which people
suffered stinging eyes and runny
noses; visibility also decreased
(illustration)
• Los Angeles County Air Pollution
Control District created through state
legislation in 1947
• Agency attacked stationary sources
believed to be primary cause of problem.
For example:
– banned backyard garbage incinerators
– mandated emission controls for area steel
and iron mills
• In 1967, the state created the Air
Resources Board
• The regional air quality district AQMD
covering the counties in Los Angeles
metropolitan areas created in 1975
• The source of LA’s primary air quality
problem was discovered in late 1940’s
• Ozone, a gas found in the upper
atmosphere, was forming near ground
level
• Ground level ozone is more likely to form
on hot days that experience temperature
inversion
• Research showed most of the
emissions producing ozone came
from car exhaust
• Auto companies reluctant to develop
emissions reduction technology
• Over the years, the state of California
grew to confront auto industry
• In mid-1960’s auto industry
began equipping cars with
emissions control gear
• Over 15 years after science
indicated cars were the
problem
What was the reason for
reluctance of the industry?
–Clean air is public good
–Market incentives are not strong to
produce the good
–Market incentives to alter other
aspects of autos much stronger
• Suppose domestic car industry made up of
GM and Ford
• What is payoff to the companies under
scenarios?
Ford does not
employ pollution
gear
GM does not
employ pollution
gear
GM employs
pollution gear
Ford employs
pollution gear
Other proposed solutions
Would high gasoline taxes have addressed
problem?
– Geography of tax
– Support for tax
Public Transportation?
– in mid-1950’s there were 7.1 persons for
every vehicle in the city of New York, 2.8
persons per vehicle in Los Angeles
Hoy No Circula policy of Mexico City?
• In 1955 LA county developed world’s first
pollution alert system
• Developed system of air monitoring
Alert
First Stage
Second Stage
Third Stage
Ozone Level
0.5ppm
1 ppm
1.5 ppm
• Ozone level at first stage would
today be considered an extreme
health hazard
• Today, the federal standard in
which adverse health effects is
estimated to begin is 0.075 ppm
average over an 8 hour period
• 15 first stage alerts in 1955
• 10 in 1956
• Highest recorded ozone in
history in LA area was 0.68
ppm in 1955
• Last time ozone recorded over
0.50 ppm in LA area was in
1974
• In 1970’s, statewide alert standard adopted
• Ozone ppm levels averaged over 1 hour
Alert
Ozone Level
Health Advisory
0.15 ppm
Stage 1
0.20 ppm
Stage 2
0.35 ppm
Stage 3
0.50 ppm
• Over the years, air quality in
LA has dramatically improved;
mainly due to auto emissions
technology
• Although area still has worst
air quality in the country
Los Angeles Area Air Quality