chemical aspect of air polution

7/30/2019 Chemical Aspect of Air Polution

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Section 7

Chemical Aspectsof Air Pollution

Overview of Basic Pollutants

OzoneParticulate Matter

Carbon Monoxide

Sulfur Dioxide

Nitrogen Oxides


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Section 7 Chemical Aspects of Air Pollution

2


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Photochemical Smog

Air pollution formed by sunlight catalyzing chemical reactionsof emitted compounds

Los Angeles, California

Early pollution due to London-type smog.

1905-1912, L.A. City Council adopts regulation controlling smoke

Early 1900s, automobile use increases.

1939-1943 visibility decreases significantly.

Plume of pollution engulfs downtown (26 July 1943).

1943: L.A. County Board of Supervisors bans emission of dense

smoke and creates office called Director of Air Pollution Control 1945. L.A. Health Officer suggests pollution due to locomotives,

diesel trucks, backyard incinerators, lumber mills, dumps, cars.

1946. L.A. Times hires air pollution expert to find methods to

ameliorate pollution.


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Los Angeles, California

(December 3, 1909)

Library of Congress Prints and Photographs Division, Washington, D. C.


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Discovery of Ozone in Smog

1948: Arie Haagen-Smit (1900-1977), biochemistry professor atCaltech, begins to study plants damaged by smog.

1950: Finds that plants sealed in a chamber and exposed toozone exhibit similar damage as did plants in smog

Also finds that ozone caused eye irritation, damage to materials,

respiratory problems. Other researchers find that rubber cracks within minutes when

exposed to high ozone.

1952: Haagen-Smit finds that ozone forms when oxides ofnitrogen and reactive organic gases are exposed to sunlight.Postulates that ozone and precursors are main constituents ofL.A. smog.

Oil companies and business leaders argue that ozone in L.A.originates from stratosphere.

Measurements of low ozone over Catalina Island disprove this.


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Basic Pollutants (1 of 3)

Categories of pollutants Primary emitted directly from a source

Secondary formed in the atmosphere from a reaction of

primary pollutants

Precursors primary pollutants (gases) that participate inthe formation of secondary pollutants

Pollutants originate from Combustion of fossil fuels and organic matter

Evaporation of petroleum products or compounds used incommercial products, services, and manufacturing

Natural production of smoke from fires, dust from strong

winds, and emissions from the biosphere and geosphere


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PrimarySO2

Sulfur Dioxide

Primary & SecondaryPMParticulate Matter

Primary & SecondaryHC

Hydrocarbon Compounds

(also called VOCs volatile

organic compounds )

SecondaryNO2Nitrogen Dioxide

SecondaryO3Ozone

PrimaryCOCarbon Monoxide

TypeAbbreviationPollutant



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Basic Pollutants Toxics (1 of 2)

Air toxics (hazardous air pollutants) are known orsuspected to cause cancer or other serious health

effects.

EPAs 188 hazardous air pollutants include

Benzene (motor fuel, oil refineries, chemical processes)

Perchlorethylene (dry cleaning, degreasing)

Chloroform (solvent in adhesive and pesticides, by-product of

chlorination processes)

BTEX, Dioxins, PAHs, Metals (Hg, Cr)

National air toxics emissions sources in 1996

U.S. Environmental Protection Agency, 1998

Area/

Other

25%

Mobile

(nonroad)

20%

Mobile

(onroad)

31%

Point

24%


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Basic Pollutants Toxics (2 of 2)

Differences between toxics and criteriapollutants

Health criteria are different

No AQI-like standards for toxics

Cancer/non-cancer benchmarks (long-term exposures)

Short-term exposure limits for some

A challenge to monitor

Usually not available in real-time

Example: Dioxin requires 28 days of sampling

to acquire measurable amounts in ambient air

Often localized near source


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Basic Pollutants Sources(1 of 4)

Combustion

Evaporation

Natural Production


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Basic Pollutants Sources(2 of 4)

Combustion Complete combustion

Fuel water and carbon dioxide (CO2)

Incomplete combustion

Fuel water, CO2, and other pollutants

Pollutants are both gases and particles


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Basic Pollutants Sources (3 of 4)

Evaporation Thousands of chemical compounds

Liquids evaporating or gases being released

Some harmful by themselves, some react to produce other

pollutants

Many items you can smell are evaporative pollutants

Gasoline benzene (sweet odor, toxic, carcinogenic)

Bleach chlorine (toxic, greenhouse gas)

Trees pinenes, limonene (ozone- and particulate matter forming)

Paint volatile organic compounds (ozone- and particulate matterforming)

Baking bread, fermenting wine and beer VOCs and ethanol (ozone-

forming)


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Basic Pollutants Sources (4 of 4)

Natural Production Fires (combustion) produce

gases and particles

Winds pick up dust, dirt,

sand and create particlesof various sizes

Biosphere emits gases from

trees, plants, soil, ocean,

animals, microbes Volcanoes and oil seeps

produce particles and gases


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Ozone

Colorless gas Composed of three oxygen atoms

Oxygen molecule (O2)needed to sustain life

Ozone (O3) the extra oxygen atom makes ozone

very reactive

Secondary pollutant that forms from precursorgases

Nitric oxide combustion product Volatile organic compounds (VOCs) evaporativeand combustion products


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Solar radiation and chemistry

The reaction that produces ozone in theatmosphere:

O + O2 + M O3 + M

Difference between stratospheric andtropospheric ozone generation is in the sourceof atomic O

For solar radiation with a wavelength of less

than 242 nm:O2 + hv O + O


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Solar radiation and chemistry

Photochemical production of O3 in troposphere tied to NOx (NO +NO2)

For wavelengths less than 424 nm:

NO2 + hv NO + O

But NO will react with O3

NO + O3 NO2

Cycling has no net effect on ozone


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Tropospheric Ozone Photolysis

Troposphere ozone photolysis takes place in a narrow UV window(300-320 nm), NO2 broadly below 428

30o equinoxmiddaySolar spectrum


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Nitrogen Oxides

Nitrogen oxides, or NOx, is the generic term for a group ofhighly reactive gases, all of which contain nitrogen andoxygen in varying amounts.

Nitrogen dioxide is most visually prominent (it is the yellow-brown color in smog)

The primary man-made sources of NOx are motor vehicles;electric utilities; and other industrial, commercial, andresidential sources that burn fuels

Affects the respiratory system

Involved in other pollutant chemistry One of the main ingredients in the formation of ground-level ozone Reacts to form nitrate particles, acid aerosols, and NO2, which also

cause respiratory problems

Contributes to the formation of acid rain (deposition)


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Must make NO2

To make significant amounts of ozone musthave a way to make NO2 without consuming

ozone

Presence of peroxy radicals, from the oxidation

of hydrocarbons, disturbs O3-NO-NO2 cycleNO + HO2 NO2 + OH

NO + RO2 NO2 + RO

leads to net

production of ozone


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The Hydroxyl Radical

produced from ozone photolysis for radiation with wavelengths less than 320

nm:

O3 + hv O(1D) + O2

followed byO(1D) + M O(3P) + M (+O2O3) (~90%)

O(1D) + H2O 2 OH (~10%)

OH initiates the atmospheric oxidation of a wide range ofcompounds in the atmosphere

referred to as detergent of the atmosphere

typical concentrations near the surface ~106 - 107cm-3

very reactive, effectively recycled


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Section 7 Chemical Aspects of Air Pollution22

THE OH RADICAL: MAIN

TROPOSPHERIC OXIDANT

Primary source: O3 + hn O2 + O(1D) (1)

O(1D) + M O + M (2)

O(1D) + H2O 2OH (3)

Sink: oxidation of reduced species leadsto HO2(RO2) production

CO + OH CO2 + H

CH4 + OH CH3 + H2O

HCFC + OH

Global Mean [OH] = 1.0x106 molecules

cm-3

MajorOH sinks


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Oxidation of CO - production of ozone

CO + OH CO2 + H

H + O2 + M HO2 + M

NO + HO2 NO2 + OH

NO2 + hv NO + OO + O2 + M O3

CO + 2 O2 + hv CO2 + O3


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Carbon Monoxide

Odorless, colorless gas

Caused by incomplete combustion of fuel

Most of it comes from motor vehicles

Reduces the transport of oxygen through thebloodstream

Affects mental functions and visual acuity,

even at low levels


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What breaks the cycle?

Cycle terminated byOH + NO2 HNO3

HO2 + HO2 H2O2

Both HNO3 and H2O2 will photolyze or react with OH

to, in effect, reverse these pathways but reactions are slow (lifetime of several days)

both are very soluble - though H2O2 less-so

washout by precipitation

dry deposition in PBL they are effectively a loss

situation is more complicated in the uppertroposphere

no dry deposition, limited wet removal


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Ozone ChemistrySummary of ozone chemistry

NO2 + Sunlight NO + O Production

O+ O2 O3 Production

NO + O3 NO2 + O2 Destruction VOC + OH RO2 + H2O Production of NO2 without the

RO2 + NO NO2 + RO Destruction of O3

Emissions Chemistry

Meteorology

Key processes

Ample sunlight (ultraviolet) High concentrations of precursors (VOC, NO, NO2)

Weak horizontal dispersion

Weak vertical mixing

Warm air

RO=Reactive Organic compound such as VOC

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Day and Night Chemistry

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Ozone Precursor Emissions (1 of 2)

Man-made sources Oxides of nitrogen (NOx) through

combustion

VOCs through combustion and

numerous other sources Natural sources (biogenic)

VOCs from trees/vegetation

NOx from soils (Midwest fertilizer)

Concentration depends on Source location, density, andstrength

Meteorology

Emissions Chemistry

Meteorology

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NOx EMISSIONS (Tg N yr-1) TO TROPOSPHERE

Fossil Fuel23.1

Aircraft0.5

Biofuel2.2

BiomassBurning

5.2

Soils5.1

Lightning5.8

Stratosphere0.2

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An example of gridded NOx emissions

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Mapping of Tropospheric NO2

From the GOME satellite instrument (July 1996)

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GOME Can Provide Info on Daily Info

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Lightning Flashes Seen from Space

2000 data

DJF

JJA

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Global Budget of CO

AREP Satellite Observations of Biomass


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Satellite Observations of Biomass

Fires (1997)

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Daily Los Angeles Emission (1987)

Gas Emission (tons/day) Percent of totalCarbon monoxide 9796 69.3

Nitric oxide 754

Nitrogen dioxide 129

Nitrous acid 6.5

Total NOx+HONO 889.5 6.3

Sulfur dioxide 109

Sulfur trioxide 4.5Total SO

x113.5 0.8

Alkanes 1399

Alkenes 313

Aldehydes 108

Ketones 29

Alcohols 33

Aromatics 500

Hemiterpenes 47

Total ROGs 2429 27.2

Methane 904 6.4

Total emission 14,132 100

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Percent Emission by Source-LA

Table 4.2

Source Category CO(g) NOx(g) SOx(g) ROG

Stationary 2 24 38 50

Mobile 98 76 62 50

Total 100 100 100 100

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Most Important Gases in Smog in Terms of

Ozone Reactivity and Abundance

Table 4.4

1. m- andp-Xylene

2. Ethene

3. Acetaldehyde

4. Toluene5. Formaldehyde

6. i-Pentane

7. Propene

8. o-Xylene9. Butane

10. Methylcyclopentane

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Lifetimes of ROGs Against Chemical

Loss in Urban Air

Table 4.3

ROG Species Phot. OH HO2 O NO3 O3

n-Butane --- 22 h 1000 y 18 y 29 d 650 y

trans-2-butene --- 52 m 4 y 6.3 d 4 m 17 m

Acetylene --- 3 d --- 2.5 y --- 200 d

Formaldehyde 7 h 6 h 1.8 h 2.5 y 2 d 3200 y

Acetone 23 d 9.6 d --- --- --- ---

Ethanol --- 19 h --- --- --- ---

Toluene --- 9 h --- 6 y 33 d 200 d

Isoprene --- 34 m --- 4 d 5 m 4.6 h

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Summary

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Ozone Meteorology Key Processes

Dispersion (horizontal mixing)

Vertical mixing

Sunlight

Transport

Weather pattern

Geography

Diurnal

Season

Emissions Chemistry

Meteorology

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Ozone Precursor Emissions (2 of 2)

Key processes

Source location, density, and strength

Dispersion (horizontal mixing) - wind speed

Vertical mixing - inversion

Concentration S/WS

Wind speed (WS)

S

Courtesy of New Jersey

Department of Environmental Protection

Concentration S/VM

Vertical mixing (VM)S

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Daily Variation

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Source/Receptor Regions in Los Angeles

.

.

.

H o u r o f d a y

O

N ON O

C e n t ra l L o s A n g e le s

A u g u s t ,

V

olumemixin

gratio(ppmv)

Figure 4.10

.

.

.

Vol

umemixingratio(ppmv)

H o u r o f d a y

O

N O

N O

S a n B e r n a r d in o

A u g u s t ,

V

olumemixin

gratio(ppmv

)

Urban center Sub-urban

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. .

.

.

.

.

.

ROG (ppmC)

NOx

(g)(ppmv)

..

.

.

.

=O

(g),ppm

v

Ozone Isopleth Plot

Figure 4.9Contours are ozone (ppmv)

NO

x(ppmv)

0.2

40.0

8 0.3

2

0.1

6

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THIS OZONE BACKGROUND IS A SIZABLE INCREMENTTHIS OZONE BACKGROUND IS A SIZABLE INCREMENT

TOWARDS VIOLATION OF U.S. AIR QUALITY STANDARDSTOWARDS VIOLATION OF U.S. AIR QUALITY STANDARDS

(even more so in Europe!)(even more so in Europe!)

ppbv

Europe(seasonal)

U.S.(-h avg.)

U.S.(-h avg.)

preindustrial present

background

Europe(-h avg.)

Slide courtesy of D. Jacob

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S U R F A C E O Z O N E E N H A N C E M E N T S C A U S E D B YS U R F A C E O Z O N E E N H A N C E M E N T S C A U S E D B Y

A N T H R O P O G E N I C E M IS S IO N S F R O M D IF F E R E N T C O N T I N E N T SA N T H R O P O G E N IC E M IS S IO N S F R O M D IF F E R E N T C O N T I N E N T SG E O S-C H E Mm o d e l , J u l y

N o r th A m e r i c a

E u r o p e

A s i a

L i e t a l . [ ]

EU/USA

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P ti l t M tt


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Particulate Matter(1 of 3)

Ultra-fine fly-ash or

carbon soot

*24-hour average24-hour average

Complex mixture of solid and liquid particles

Composed of many different compounds Both a primary and secondary pollutant

Sizes vary tremendously

Forms in many ways

Clean-air levels are < 5 g/m3 *

Background concentrations can be higher

due to dust and smoke

Concentrations range from 0 to 500+ g/m3 *

Health concerns

Can aggravate heart diseases

Associated with cardiac arrhythmias and heart attacks

Can aggravate lung diseases such as asthma and bronchitis

Can increase susceptibility to respiratory infection

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P ti l t M tt


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Particulate Matter(2 of 3)Particles come in different shapes and sizes

Particle sizes

Ultra-fine particles (


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Particulate Matter(3 of 3)

A clear (left) and dirty (right) PM filter

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Particulate Matter Composition (1 of 3)

Primary PM (directlyemitted)

Suspended dust Sea salt

Organic carbon

Elemental carbon

Metals from combustion

Small amounts of sulfateand nitrate

Secondary PM (precursor gases

that form PM in the atmosphere)

Sulfur dioxide (SO2): forms sulfates

Nitrogen oxides (NOx): forms

nitrates

Ammonia (NH3): forms ammonium

compounds

Volatile organic compounds(VOCs): form organic carbon

compounds

PM is composed of a mixture of primary and secondarycompounds.

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NaCl salt is found in PM near seacoasts and after de-icing materialsare applied

Organic Carbon (OC) consists of

hundreds of separate compoundscontaining mainly carbon, hydrogen,and oxygen

Elemental Carbon (EC) composed of carbon without muchhydrocarbon or oxygen. EC isblack, often called soot.

Liquid Water soluble nitrates,sulfates, ammonium, sodium, otherinorganic ions, and some organicmaterial absorb water vapor fromthe atmosphere

Particulate Matter Composition (3 of 3)

Chow and Watson (1997)

Geological Material suspended

dust consists mainly of oxides of Al,

Si, Ca, Ti, Fe, and other metal

oxides

Ammonium ammonium bisulfate,

sulfate, and nitrate are most

common

Sulfate results from conversion of

SO2 gas to sulfate-containing

particles

Nitrate results from a reversible

gas/particle equilibrium between

ammonia (NH3), nitric acid (HNO3),

and particulate ammonium nitrate

Most PM mass in urban and nonurban areas is composed of acombination of the following chemical components

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PM Emissions Sources(1 of 4)

Point generally a major facility emitting pollutants from identifiable

sources (pipe or smoke stack). Facilities are typically permitted.

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Area any low-level source of air pollution released over

a diffuse area (not a point) such as consumer products, architecturalcoatings, waste treatment facilities, animal feeding operations, construction,

open burning, residential wood burning, swimming pools, and charbroilers

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PM Emissions Sources(3 of 4)Mobile

On-road is any moving source of air pollution such as cars, trucks,

motorcycles, and buses Non-road sources include pollutants emitted by combustion engines on

farm and construction equipment, locomotives, commercial marine

vessels, recreational watercraft, airplanes, snow mobiles, agricultural

equipment, and lawn and garden equipment

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Natural biogenic and geogenic emissions from wildfires, wind blown

dust, plants, trees, grasses, volcanoes, geysers, seeps, soil, andlightning

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COMPOSITION OF PM2.5 IS HIGHLY VARIABLE (NARSTO PM

ASSESSMENT)


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Toronto( - )Egbert ( - )

Abbotsford( - )

Quaker CityOH( )

ArendstvillePA( )

Atlanta( )Yorkville( )MexicoCity- Pedregal ( )

LosAngeles( - )

Fresno( - )

KernWildlifeRefuge( - )

Sulfate

Nitrate

AmmoniumBlackcarbon

Organiccarbon

Soil

Other

. ugm -. ugm -

. ugm -

. ugm -

. ugm -

. ugm -. ugm -

.ugm -

. ugm -

. ugm -

. ugm -

WashingtonDC( - )

. ugm -

ColoradoPlateau( - )

. ugm -

MexicoCity-Netzahualcoyotl ( )

.ugm -

Esther ( - )

St. Andrews( - )

.ugm -

.ugm -

ASSESSMENT)

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GAWORIGIN OF THE ATMOSPHERIC AEROSOL


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Soil dustSea salt

Aerosol: dispersed condensed matter suspended in a gasSize range: 0.001 m (molecular cluster) to 100 m (small raindrop)

Environmental importance: health (respiration), visibility, radiative balance,cloud formation, heterogeneous reactions, delivery of nutrients

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Particulate Matter Chemistry (1 of 4)

Coagulation: Particles collide and stick together.

Condensation: Gases condense onto a small solid particle

to form a liquid droplet.

Chemical Reaction: Gases react to form particles.

Cloud/Fog Processes: Gases dissolve in a water droplet and chemically

react. A particle exists when the water evaporates.

Sulfate

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P ti l t M tt C iti


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NOx

Ammoni

a

VOCs

Particulate Matter Composition (2 of 3)PM contains many compounds

Primary Particles

(directly emitted)Secondary Particles

(from precursor gases)

Other(sea salt)

Crustal

(soil,dust)

Organic

CarbonCarbon

(Soot)SO2

Ammonium

Sulfate

Ammonium

Nitrate

Metals

Composition of PM

tells us about

the sources and

formation processes

Gas

Particle

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Sulfur Dioxide

Sulfur dioxide (SO2) belongs to the family of sulfuroxide (SOx) gases.

Gases are formed when fuel containing sulfur (mainly

coal and oil) is burned and during metal smelting and

other industrial processes. Affects the respiratory system

Reacts in the atmosphere to form acids, sulfates, and

sulfites

Contributes to acid rain

Low crown density

of spruce trees

German sandstone

statue, 1908, 1969

Impact of low soil

pH on agriculture

in Victoria

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Sulfate Chemistry Virtually all ambient sulfate (99%)

is secondary, formed within theatmosphere from SO2 during the

summer.

About half of SO2 oxidation to sulfate

occurs in the gas phase through

photochemical oxidation in the daytime.NOx and hydrocarbon emissions tend to

enhance the photochemical oxidation rate.

At least half of SO2 oxidation takes place

in cloud droplets as air molecules react in clouds.

Within clouds, soluble pollutant gases, such as SO2

, are scavenged

by water droplets and rapidly oxidize to sulfate. Only a small fraction of cloud droplets deposit out as rain; most

droplets evaporate and leave a sulfate residue or convective debris. Typical conversion rate 1-10% per hour

Husar (1999)

Heterogeneous Oxidation

Particulate Matter Chemistry(2 of 4)

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M h i f C ti S(IV) t


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Mechanisms of Converting S(IV) to

S(VI)

Why is converting to S(VI) important?

It allows sulfuric acid to enter or form within cloud drops

and aerosol particles, increasing their acidity

Mechanisms

1. Gas-phase oxidation of SO2(g) to H2SO4(g) followed by

condensation of H2SO4(g)

2. Dissolution of SO2(g) into liquid water to form

H2SO3(aq) followed by aqueous chemical conversion of

H2SO3(aq) and its dissociation products to H2SO4(aq) and

its dissociation products.

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Particulate Matter Chemistry(3 of 4)

Nitrate Chemistry NO2 can be converted to nitric acid (HNO3) by reaction with

hydroxyl radicals (OH) during the day.

The reaction of OH with NO2 is about 10 times faster than the OH

reaction with SO2.

The peak daytime conversion rate of NO2 to HNO3 in the gas phase

is about 10% to 50% per hour.

During the nighttime, NO2 is converted into HNO3 by a series of

reactions involving ozone and the nitrate radical.

HNO3 reacts with ammonia to form particulate ammonium nitrate(NH4NO3).

Thus, PM nitrate can be formed at night and during the day;

daytime photochemistry also forms ozone.

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Winds Clouds, fog Winds Temperature

Temperature Temperature Precipitation Relative humidity

Solar radiation Relative humidity Winds

Vertical mixing Solar radiation

condensation and

coagulation

photochemical production

cloud/fog processes

gases condense onto particles

cloud/fog processes Measurement

Issues Inlet cut points Vaporization of

nitrate, H2O, VOCs

Adsorption of VOCs Absorption of H2O

transport

sedimentation(dry deposition)

wet deposition

Mechanical Sea salt Dust

Combustion Motor vehicles Industrial

Fires

Other gaseous

Biogenic Anthropogenic

Particles NaCl Crustal

Particles Soot Metals

OCGases

NOx SO2 VOCs

NH3Gases

VOCs NH3 NOx

SourcesSample

CollectionPM Transport/LossPM

FormationEmissionsChemical Processes

Meteorological Processes

Particulate Matter Chemistry (4 of 4)

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Partic late Matter Meteorolog


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Phenomena Emissions PM Formation PM Transport/Loss

Aloft Pressure

Pattern

No direct impact. No direct impact. Ridges tend to produce conditions conducive for accumulation of PM2.5

.

Troughs tend to produce conditions conducive for dispersion and removal of PM and ozone.In mountain-valley regions, strong wintertime inversions and high PM2.5

levels may not be

altered by weak troughs.High PM

2.5concentrations often occur during the approach of a trough from the west.

Winds andTransport

No direct impact. In general, stronger winds dispersepollutants, resulting in a less idealmixture of pollutants for chemicalreactions that produce PM

2.5.

Strong surface winds tend to disperse PM2.5

regardless of season.

Strong winds can create dust which can increase PM2.5

concentrations.

TemperatureInversions

No direct impact. Inversions reduce vertical mixing andtherefore increase chemical

concentrations of precursors. Higherconcentrations of precursors canproduce faster, more efficient chemicalreactions that produce PM

2.5.

A strong inversion acts to limit vertical mixing allowing for the accumulation of PM2.5

.

Rain Reduces soil and fire emissions Rain can remove precursors of PM2.5

. Rain can remove PM2.5

.

Moisture No direct impact. Moisture acts to increase the productionof secondary PM

2.5including sulfates and

nitrates.

No direct impact.

Temperature Warm temperatures are associated withincreased evaporative, biogenic, and

power plant emissions, which act toincrease PM

2.5. Cold temperatures can

also indirectly influence PM2.5

concentrations (i.e., home heating onwinter nights).

Photochemical reaction rates increasewith temperature.

Although warm surface temperatures are generally associated with poor air quality conditions,very warm temperatures can increase vertical mixing and dispersion of pollutants.

Warm temperatures may volatize Nitrates from a solid to a gas.Very cold surface temperatures during the winter may produce strong surface-basedinversions that confine pollutants to a shallow layer.

Clouds/Fog No direct impact. Water droplets can enhance theformation of secondary PM

2.5. Clouds can

limit photochemistry, which limitsphotochemical production.

Convective clouds are an indication of strong vertical mixing, which disperses pollutants.

Season Forest fires, wood burning, agriculture

burning, field tilling, windblown dust,road dust, and construction vary byseason.

The sun angle changes with season,

which changes the amount of solarradiation available for photochemistry.

No direct impact.

Particulate Matter MeteorologyHow weather affects PM emissions, formation, and transport

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GAW ANNUAL MEAN PARTICULATEMATTER (PM) CONCENTRATIONS AT


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U.S. SITES, 1995-2000

NARSTO PM Assessment, 2003

PM10 (particles > 10 m) PM2.5 (particles > 2.5 m)

Red circles indicate violations of national air quality standard:50 g m-3 for PM10 15 g m-3 for PM2.5

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GAWAEROSOL OPTICAL DEPTH (GLOBAL MODEL)


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AEROSOL OPTICAL DEPTH (GLOBAL MODEL)

Annual mean

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GAWAEROSOL OBSERVATIONS FROM SPACE


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AEROSOL OBSERVATIONS FROM SPACE

Biomass fire haze in central America yesterday (4/30/03)

Fire locationsin red

Modis.gsfc.nasa.gov

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GAW BLACK CARBON EMISSIONS


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BLACK CARBON EMISSIONS

Chin et al. [2000]

DIESEL

DOMESTICCOAL BURNING

BIOMASSBURNING

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GAW RADIATIVE FORCING OF CLIMATE, 1750-PRESENT


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Kyoto also failed to address two major pollutants that have an impact onwarming:black soot and tropospheric ozone.Both are proven health

hazards.Reducing both would not only address climate change, but also

dramatically improve people's health. (George W. Bush, June 11 2001 Rose

Garden speech)

IPCC [2001]

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GAW Particles Impact Human Health and MORE


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p

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GAWEPA REGIONAL HAZE RULE: FEDERAL CLASS I AREAS TO RETURN TO

NATURAL VISIBILITY LEVELS BY 2064


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NATURAL VISIBILITY LEVELS BY 2064

Acadia National Park

clean day moderately polluted day

http://www.hazecam.net/

will require essentially total elimination of anthropogenic aerosols!

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GAW ASIAN DUST INFLUENCE IN UNITED STATES


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Dust observations from U.S. IMPROVE network

April 16, 2001Asian dust in western U.S.

April 22, 2001Asian dust in southeastern U.S.

GlenCanyon,AZ

Clear day April 16, 2001: Asian dust!

0 2 4 6 8g m-3

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GAWAerosols Link Air Quality, Health andCli t


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Climate:

Dirtier Air and a Dimmer Sun

Anderson et al., Science 2003 Smith et al., 2003 He et al., 2002

chemical aspect of air polution

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