Transcript Slide 1

Air Quality Primer
Lyle Chinkin
Sonoma Technology, Inc.
Petaluma, CA
Presented at the
Sierra Ozone Summit
Grass Valley, California
June 4, 2008
STI-708024
Overview
• The history of smog
• The major air pollutants, formation processes, and
emission sources (emphasis on ozone)
• The role of weather (meteorology) in ozone transport
• Previous transport studies and findings
• Conclusions
2
History of Smog (1 of 4)
Origin: smoke and fog = Smog
• Mixture of chemically
reactive compounds in the
atmosphere.
• The word “smog” coined
in early 1900s by Harold A.
Des Veaux to describe
conditions of sooty fog in
Britain.
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History of Smog (2 of 4)
1943:
First recognized episodes of smog occurred in Los Angeles.
Visibility was only three blocks and people suffered from
itchy eyes, respiratory discomfort, nausea, and vomiting.
The phenomenon was termed a "gas attack" and blamed
on a nearby butadiene plant.
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History of Smog (3 of 4)
1952 London, four days in December
• Mix of dense fog and sooty black coal smoke
• Killed thousands of Londoners
"Night at Noon." London's Piccadilly Circus at
midday, during another deadly smog episode,
this time in the winter of 1955.
Source: When Smoke Ran Like Water,
Devra Davis, Perseus Books
Central London during the killer smog, December 1952. Visibility was less than 30
feet. During the height of the smog, people could not see their own hands or feet,
and buses had to be led by policemen walking with flares.
Source: When Smoke Ran Like Water, Devra Davis, Perseus Books
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History of Smog (4 of 4)
1960 Air Pollution Potential – forecasting began
1963 National Air Pollution Control Agency – started as a
research body; not very effective
1967 The Air Quality Act of 1967
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Designation of air quality regions
Regional approach to pollution control
1970 A turning point
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Attitudinal change in U.S. society
National Environmental Policy Act (January 1)
Formation of Environmental Protection Agency (July 9)
Clean Air Act of 1970
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–
National Air Quality Standards
Statutory deadlines for compliance
1990 Clean Air Act Amendments
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What Makes Up Clean Air ?
What is in our air?
Mixture of invisible gases, particles, and water
Mostly nitrogen (78%) and oxygen (21%)
Other
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•
•
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Argon
Water vapor
Carbon dioxide
Ozone
Particulate matter
and many more
Rem aining 1%
Oxygen 21%
Nitrogen
78%
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Major Types of Air Pollutants
Categories of pollutants
• Primary – emitted directly from source
• Secondary – formed in atmosphere from reaction
of primary pollutants
• Precursors – primary pollutants (gases) that form
secondary pollutants
Pollutants originate from
• Combustion - fossil fuels, organic matter
• Evaporation - petroleum products, solvents
• Natural production - smoke, dust, and emissions
from trees and plants
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Criteria Pollutants
Response to 1970 Clean Air Act
Established the National Ambient Air Quality
Standards (NAAQS) for six pollutants:
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Nitrogen dioxide (NO2)
Ozone (O3)
Sulfur dioxide (SO2)
Particulate matter (PM10)
Particulate matter (PM2.5)*
Lead (Pb)
Carbon monoxide (CO)
*
the remainder of this
discussion will focus
on ozone
established after 1970
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What is Ozone? (1 of 2)
O3
Good Ozone: a naturally-occurring
constituent of the upper-atmosphere
protecting the earth from the sun’s
UV rays.
Bad Ozone (ground level): Formed at
the Earth’s surface where it causes health
problems in humans and damage to
many plant species.
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What is Ozone? (2 of 2)
A colorless gas composed of three oxygen atoms
• Oxygen molecule (O2) – needed to breathe to sustain
life
• Ozone (O3) – extra oxygen atom makes ozone very
reactive
A secondary pollutant that forms from precursor gases
• NOx (nitrous oxides) – combustion product
• VOCs (volatile organic compounds) – evaporative
and combustion products
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Ozone Formation
Recipe for Ozone
Oxides of
Nitrogen
(NOX)
Fossil fuel combustion
+
Volatile Organic
Compounds
(VOC)
+
UV
=
Ozone
(O3)
Gasoline combustion
Gasoline evaporation
Solvent evaporation
Natural – trees and plants
Key factors:
Sunlight (ultraviolet) needed
Relative amount of VOC and NO is critical
Heat speeds up chemical reactions
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Ozone Characteristics
Clean-air background levels are 35-40 ppb* (sometimes lower)
U.S. concentrations range from 0 to 250+ ppb*
Ozone health concerns
• A severe irritant (reactive).
• Inflames and irritates the respiratory tract, particularly during
physical activity. Breathing ozone can worsen asthma
attacks.
• Symptoms include breathing difficulty, coughing, and throat
irritation.
• Medical studies have shown that ozone damages lung
tissue; complete recovery may take several days after
exposure.
*
One-hour average
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Ozone Lifecycle – Day/Night (1 of 2)
Note:
the Northern Sierra Air
Quality Management
District comprises the
northern portion of the
Mountain Counties Air
Basin
8-Hour Average Ozone (July 9, 2002)
120
80
60
40
20
22
20
18
Time (LST)
16
14
12
10
8
6
4
2
0
0
Concentration
(ug/m3)
(ppb)
Concentration
100
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Ozone Lifecycle – Day/Night (2 of 2)
8-Hour Average Ozone (July 9, 2002)
100
80
60
40
20
22
20
18
Time (LST)
16
14
12
10
8
6
4
2
0
0
Concentration (ppb)
(ug/m3)
Concentration
120
Ozone is transported from one area to the next
Along the way:
- photochemical reactions continue
- fresh emissions are infused
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Key Weather Factors
Key factors that influence air quality
• Winds
• Inversions
• Sunlight and clouds
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Winds – Dispersion
How do winds affect pollution?
Disperse pollutants – the spreading of atmospheric constituents.
Introduce dispersion process
• Molecular Diffusion (not efficient)
• Atmospheric turbulence
– Mechanical
– Shear
– Buoyancy (convective)
Resource: meted.ucar.edu/dispersion/basics/navmenu0.htm
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Winds – Transport
How do winds affect pollution?
Pollutant transport –
Movement of pollutants from
one area to another by the wind
Types
• Neighborhood scale: monitor
to monitor
• Regional scale: city to city
and state to state
Transport of pollution from the Los Angeles Basin to the
Mojave Desert (Courtesy of Don Blumenthal)
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Inversions
Inversions occur when temperature increases with
height.
Inversions are important because they trap
pollution near the earth’s surface.
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Inversion – Example
Simplified vertical temperature profile
Warm
Inversion
Cool
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Sunlight and Clouds
Affect on ozone
Ozone
Sunlight
Promotes
Photochemistry
Clouds
Reduce
Photochemistry
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Regional Ozone – Southerly Winds (1 of 2)
Afternoon
Wind
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Regional Ozone – Northerly Winds (2 of 2)
Afternoon
Wind
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Regional Ozone Characteristics
(1 of 3)
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16
Number of days
14
12
10
8
6
4
2
0
Apr
May
Jun
Jul
Aug
Sep
Oct
Month
Sacramento
Auburn
Grass Valley
Average number of days by month with
ozone concentrations > than 75 ppb
8-hour average concentrations
2003 – 2007
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Regional Ozone Characteristics
(2 of 3)
70
60
Number of days
50
40
30
20
10
0
2003
2004
2005
2006
2007
Year
Sacramento
Auburn
Grass Valley
Total number of days by year with
ozone concentrations > than 75 ppb
8-hour average concentrations (April-October)
2003 – 2007
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Sacramento
Auburn
Oct-06
Jul-06
Apr-06
Jan-06
Oct-05
Jul-05
Apr-05
Jan-05
Oct-04
Jul-04
Apr-04
Jan-04
Oct-03
Jul-03
Apr-03
Jan-03
Oct-02
Jul-02
Apr-02
Jan-02
Oct-01
Jul-01
Apr-01
Jan-01
Oct-00
Jul-00
Apr-00
Jan-00
Maximum Concentration (ppb)
Regional Ozone Characteristics
(3 of 3)
140
120
100
80
60
40
20
0
Grass Valley
8-hour maximum ozone concentrations
by month and year from 2000-2006
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Previous Transport Studies
Name of Study
Researcher/Author
Regional scale transport over complex
terrain, a case study: tracing the
Sacramento plume in the Sierra Nevada
of California
John Carroll and Alan Dixon; UC Davis
(2002)
The Central California Ozone Study
(CCOS)
California Air Resources Board (2006)
Air Quality in Nevada County: Cutting
Through the Haze
Superior Court of the California County
of Nevada (2004)
2003 Air Quality Attainment Plan
Feather River Air Quality Management
District
Ozone Transport: 2001 Review
California Air Resources Board (2001)
Note: this is not a comprehensive list of previous studies
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Findings from Previous Studies
ARB transport findings (2001)
• Ozone violations are caused mainly by transport from the Sacramento
Valley, San Joaquin Valley, and San Francisco Bay Area.
• Grass Valley, Placerville, Jackson, and San Andreas can receive
pollutants from Sacramento, the San Joaquin Valley, the Bay Area or a
combination of areas depending on the weather.
• In the future, local pollutant emissions may contribute to ozone
concentrations in the region as population continues to increase.
Source: California Air Resources Board Ozone Transport: 2001 Review
(http://www.arb.ca.gov/aqd/transport/summary/transportsummary.doc)
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Conclusions
• A literature review should be performed to synthesize the findings of
recent transport studies in the Sacramento region to understand the
state-of-the-science.
• Recommendations should be made for future activities that may include:
– Field studies
– Data analysis
– Photochemical modeling
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