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Los Angeles Air Quality During hot months, Los Angeles occasionally suffers from temperature inversion Under normal conditions the air cools with distance.

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Presentation on theme: "Los Angeles Air Quality During hot months, Los Angeles occasionally suffers from temperature inversion Under normal conditions the air cools with distance."— Presentation transcript:

1 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

2 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

3 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 London1952 Great Smog in London

4 LA’s air quality began to decline as its population grew Year LA County population , ,208, ,151, ,041, ,818,605

5 Problems of smog became prominent in 1940 Episodes occurred in which people suffered stinging eyes and runny noses; visibility also decreased (illustration)illustration Los Angeles County Air Pollution Control District created through state legislation in 1947

6 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 BoardAir Resources Board The regional air quality district AQMD covering the counties in Los Angeles metropolitan areas created in 1975

7 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

8 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

9 In mid-1960’s auto industry began equipping cars with emissions control gear Over 15 years after science indicated cars were the problem

10 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

11 Suppose domestic car industry made up of GM and Ford What is payoff to the companies under scenarios? Ford does not employ pollution gear Ford employs pollution gear GM does not employ pollution gear GM employs pollution gear

12 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?

13 In 1955 LA county developed world’s first pollution alert system Developed system of air monitoring AlertOzone Level First Stage0.5ppm Second Stage1 ppm Third Stage1.5 ppm

14 First Stage: Warnings broadcast over media; people encouraged not to drive etc. Second Stage: Many stationary sources of ozone creating emissions ordered stopped Third Stage: All industrial and automotive pollution banned

15 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 ppm average over an 8 hour period

16 15 first stage alerts in 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

17 In 1970’s, statewide alert standard adopted Ozone ppm levels averaged over 1 hour AlertOzone Level Health Advisory0.15 ppm Stage ppm Stage ppm Stage ppm

18 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


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