Lyle ChinkinSonoma Technology, Inc.

Petaluma, CA

Presented at the Sierra Ozone Summit

Grass Valley, CaliforniaJune 4, 2008

Air Quality Primer

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.

3

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.

4

History of Smog (3 of 4)

"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

1952 London, four days in December• Mix of dense fog and sooty black coal smoke• Killed thousands of Londoners

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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• Designation of air quality regions• Regional approach to pollution control

1970 A turning point• Attitudinal change in U.S. society• National Environmental Policy Act (January 1) • Formation of Environmental Protection Agency (July 9) • Clean Air Act of 1970

– 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 • Argon• Water vapor • Carbon dioxide• Ozone• Particulate matter• and many more

Rem aining 1%

Nitrogen 78%

Oxygen 21%

7

Major Types of Air PollutantsCategories of pollutants• PrimaryPrimary – emitted directly from source• SecondarySecondary – formed in atmosphere from reaction

of primary pollutants• PrecursorsPrecursors – primary pollutants (gases) that form

secondary pollutants

Pollutants originate from• CombustionCombustion - fossil fuels, organic matter• EvaporationEvaporation - petroleum products, solvents• Natural productionNatural production - smoke, dust, and emissions

from trees and plants8

Criteria PollutantsResponse to 1970 Clean Air Act

Established the National Ambient Air Quality Standards (NAAQS) for six pollutants:• Nitrogen dioxide (NO2)

• Ozone (O3)

• Sulfur dioxide (SO2)

• Particulate matter (PM10)

• Particulate matter (PM2.5)*

• Lead (Pb)• Carbon monoxide (CO)

* established after 1970

the remainder of this

discussion will focus

on ozone

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What is Ozone? (1 of 2)

Good Ozone: a naturally-occurringconstituent of the upper-atmosphereprotecting the earth from the sun’sUV rays.

Bad Ozone (ground level): Formed at the Earth’s surface where it causes health problems in humans and damage to many plant species.

O3

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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 FormationRecipe for Ozone

Ozone(O3)

UV

Key factors:Key factors:Sunlight (ultraviolet) neededSunlight (ultraviolet) neededRelative amount of VOC and NO is criticalRelative amount of VOC and NO is criticalHeat speeds up chemical reactionsHeat speeds up chemical reactions

+ =+

Oxides of Nitrogen

(NOX)

Fossil fuel combustion

Volatile OrganicCompounds

(VOC)

Gasoline combustion

Gasoline evaporation

Solvent evaporation

Natural – trees and plants

12

Ozone CharacteristicsClean-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 averageOne-hour average13

Ozone Lifecycle – Day/Night (1 of 2)C

on

ce

ntr

ati

on

(p

pb

)

Note:

the Northern Sierra Air Quality Management District comprises the northern portion of the Mountain Counties Air Basin

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Ozone Lifecycle – Day/Night (2 of 2)C

on

cen

tra

tio

n (

pp

b)

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 – DispersionHow 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.htm17

Winds – TransportHow 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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InversionsInversions occur when temperature increases with

height.

Inversions are important because they trap pollution near the earth’s surface.

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Inversion – Example

Warm

Cool

Simplified vertical temperature profile

Inversion

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Sunlight and Clouds

Ozone

Sunlight Promotes

Photochemistry

Clouds Reduce

Photochemistry

Affect on ozone

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AfternoonWind

Regional Ozone – Southerly Winds (1 of 2)

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AfternoonWind

Regional Ozone – Northerly Winds (2 of 2)

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Regional Ozone Characteristics (1 of 3)

Average number of days by month with

ozone concentrations > than 75 ppb8-hour average concentrations

2003 – 2007

0

2

4

6

8

10

12

14

16

18

Apr May Jun Jul Aug Sep Oct

Month

Nu

mb

er o

f d

ays

Sacramento Auburn Grass Valley

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Regional Ozone Characteristics (2 of 3)

Total number of days by year with

ozone concentrations > than 75 ppb8-hour average concentrations (April-October)

2003 – 200725

0

10

20

30

40

50

60

70

2003 2004 2005 2006 2007

Year

Nu

mb

er o

f d

ays

Sacramento Auburn Grass Valley

0

20

40

60

80

100

120

140

Jan-

00

Apr

-00

Jul-0

0

Oct

-00

Jan-

01

Apr

-01

Jul-0

1

Oct

-01

Jan-

02

Apr

-02

Jul-0

2

Oct

-02

Jan-

03

Apr

-03

Jul-0

3

Oct

-03

Jan-

04

Apr

-04

Jul-0

4

Oct

-04

Jan-

05

Apr

-05

Jul-0

5

Oct

-05

Jan-

06

Apr

-06

Jul-0

6

Oct

-06

Sacramento Auburn Grass Valley

Ma

xim

um

Co

nce

ntr

atio

n (

pp

b)

8-hour maximum ozone concentrations

by month and year from 2000-2006

Regional Ozone Characteristics (3 of 3)

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Previous Transport Studies

Name of Study Researcher/AuthorRegional 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)28

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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