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

Year LA County population 1910 504,131 1930 2,208,492 1950 4,151,687 LA’s air quality began to decline as its population grew Year LA County population 1910 504,131 1930 2,208,492 1950 4,151,687 1970 7,041,980 2010 9,818,605

Problems of smog became prominent in 1940’s 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

In 1967, the state created the Air Resources Board 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 SCAQMD 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

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?

Alert Ozone Level First Stage 0.5ppm Second Stage 1 ppm Third Stage In 1955 LA county developed world’s first pollution alert system Developed system of air monitoring Alert Ozone Level First Stage 0.5ppm Second Stage 1 ppm Third Stage 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 0.07 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

Alert Ozone Level Health Advisory 0.15 ppm Stage 1 0.20 ppm Stage 2 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

Smog Alert Data AQI Current Los Angeles Air Quality Los Angeles Area Air Quality Historical Air Quality Data