NATS 101

Lecture 31Air Pollution Meteorology

AMS Glossary of Meteorology• air pollution—The presence of substances in the

atmosphere, particularly those that do not occur naturally.

• These substances are generally contaminants that substantially alter or degrade the quality of the atmosphere.

• The term is often used to identify undesirable substances produced by human activity, that is, anthropogenic air pollution.

• Air pollution usually designates the collection of substances that adversely affects human health, animals, and plants; deteriorates structures; interferes with commerce; or interferes with the enjoyment of life.

Major Air Pollution Episodes of Historic Significance

• Some of the worst events in the last two centuries occurred in London – Key ingredients: calm winds, fog, smoke particles

from coal burning

– 1873 - 700 deaths

– 1911- 1150 deaths

– 1952 - 4000 deaths

• Last event led to the Parliament passing a Clean Air Act in 1956

http://www.atmos.washington.edu/2005Q4/212/Kaufman_health.pdf

Major U.S. Air Pollution Episodes of Historic Significance

• U.S. air quality degraded shortly after the beginning of the industrial revolution

• Coal burning in Central and Midwest U.S. – 1948 Donora, PA in the Monongahela River Valley

– 20 deaths, 1000’s took ill in 5 days

• Prompted Air Pollution Control Act of 1955– Ignored automobiles

Major U.S. Air Pollution Episodes of Historic Significance

• 1960s - NYC had several severe smog episodes • 1950s onward – LA had many smog alerts from

an increase in industry and motor vehicle use• Led to passage of the Clean Air Act of 1970

(updated 1977 and 1990) – Empowered Federal Government to set emission

standards that each state had to meet

U.S. Air Pollution Examples

1963 photo of a severe smog episode in New York City. (Photo: AP/Wide World Photo, EPA Journal Jan/Feb 1990.)

Smog in San Gabriel Valley, 1972. (Photo: EPA.)

Air Pollution in Grand CanyonEven remote areas are

affected by pollution

Canyon on a clear day

Canyon on a hazy day

http://apollo.lsc.vsc.edu/classes/met130/notes/ Nice link to Lyndon Valley State College that has useful material for a NATS-type course

Primary PollutantsInjected directly into atmosphere

• Carbon Monoxide (CO) – odorless, colorless, poisonous gas

– byproduct of burning fossil fuels

– body acts as if CO is O2 in blood, can result in death

• Nitrogen Oxides (NOx, NO) – NO - nitric oxide

– emitted directly by autos, industry

Primary Pollutants• Sulfur Oxides (SOx)

– SO2 - sulfur dioxide

– produced largely through coal burning

– responsible for acid rain problem

• Volatile Organic Compounds (VOCs) – highly reactive organic compounds

– released through incomplete combustion and industrial sources

• Particulate Matter (dust, ash, smoke, salt) – 10 um particles (PM10) stay lodged in your lungs

– 2.5 um particles (PM2.5) can enter blood stream

Secondary PollutantsForm in atmosphere from chemical-photochemical

reactions that involve primary pollutants

• Sulfuric Acid H2SO4 – major cause of acid rain

• Nitrogen Dioxide NO2 – brownish hue L.A. Sky Colors

Dec 2000

Mark Z. Jacobson

Secondary Pollutants

• Ozone O3 – colorless gas – has an acrid, sweet smell – oxidizing agent

• Primary and secondary pollutants are found in the two types of smog: – London-type smog – LA-type photochemical smog

SMOG = SMOKE + FOG

Human Response to One Hour Pollutant Exposure (Turco, p194)

PollutantConcentration

Part per million by mass

Symptom

CO 10-30 ppmm Time distortion (typical urban level)

100 ppmmThrobbing headache (freeway background, 100 ppmm)

300 ppmmVomiting, collapse (tobacco smoke, 400 ppmm)

600 ppmm Death

CO sticks to hemoglobin, forming carboxyhemoglobin (COHb), which reduces the capacity of hemoglobin to carry O2 to cells

Physiology of Exposure to CO

http://apollo.lsc.vsc.edu/classes/met130/notes/

COHb level is 5%-15% for cig puffers!

Human Response to One Hour Pollutant Exposure (Turco, p194)

PollutantConcentration

Parts per million by mass

Symptom

NO2 0.06-0.1 ppmmRespiratory impact (long term exposure promotes disease)

1.5-5.0 ppmm Breathing difficulty

25-100 ppmm Acute asthma

150 ppmm Death (may be delayed)

Human Response to One Hour Pollutant Exposure (Turco, p194)

PollutantConcentration

Parts per million by mass

Symptom

O3 0.02 ppmm Odor threshold (sweet)

0.1 ppmmNose and throat irritation in sensitive people

0.3 ppmm General nose and throat irritation

1.0 ppmmAirway resistance, headaches (long term lead to premature aging of lung tissue)

Human Response to One Hour Pollutant Exposure (Turco, p194)

PollutantConcentration

Parts per million by mass

Symptom

SO2 0.3 ppmm Taste threshold (acidic)

0.5 ppmm Odor threshold (acrid)

1.5 ppmmBronchiolar constriction Respiratory infection

Table 12-2, p.328

Beijing Air Pollution

http://www.terradaily.com/news/pollution-05zs.html

Record Pollution Levels AQI > 300 - Hazardous 11-5-2005 AFP Photo

Where’s Beijing? 11-4-2005

NASA MODIS Visible

Fig. 12-4, p.322

Pollution Knows No Boundaries

April 2001 China Dust Transport Across Pacific

U.S. Pollutant Trends1940-1995

• Most pollutants decreased after the 1970 Clean Air Act

LeadParticulates SO2

VOC’sCONO2 is Leveling Off

Fig. 12-9, p.328

Fig. 12-10, p.329

AQI > 150 for CO, SO2, NO2, O3 and PM

http://www.arb.ca.gov/research/health/fs/pm-03fs.pdf

Table 12-1, p.320

90% total pollutants

10% total pollutants

Fig. 12-2a, p.320

Percentage of Primary

Pollutants

Fig. 12-2b, p.320

Percentage of Primary Sources

Air Pollution Weather

• Strong low-level inversion

Subsidence inversion that diurnal heating does not break or weaken significantly

• Weak surface winds

Persistent surface anticyclone

• Sunny weather for photochemical smog

• Hot weather to accelerate O3 production

Fig. 12-12, p.333

Stable Layer

Unstable Layer

Fig. 12-13, p.333

Top of Mixing Layer

Fig. 12-15, p.334

Valleys Trap PollutantsL.A. is in a basin surrounded by mountains that trap pollutants and usually has onshore flow that creates frequent inversions.

Pollutants can only escape through narrow canyons

Fig. 12-14, p.333

Leading Edge of Sea Breeze and “Smog Front” over Inland SoCal

Air Pollution Dispersion

• Air pollution dispersion is often studied with simple models, termed Box Models.  How is a box defined for the LA basin?

Box Model Boundaries for the LA Basin• Ventilation factor is a simple way of relating concentrations

of pollutants to parameters that modulate the dispersion of pollutants in a local environments.

• An increase in either the mixing height or the wind speed increases the effective volume in which pollutants are allowed to mix.

• The larger the volume, the lower the pollution concentration.• How does a box model work?

Ventilation Factor (VF)

Mixing Height

Length = Wind Speed Time

VF = Mixing Height Wind Speed

Volume ~ Length Height

Acid Rain and Deposition

• Sulfur dioxide (SO2) and oxides of nitrogen (NOx) within clouds (including fog) form acidic particles when they react with water:

SO2 + H2O H2SO4 (sulfuric acid) NOx + H2O HNO3 (nitric acid)

• Acid Rain is worse downstream of the point sources of pollution

• Acid Rain affects Trees, Lakes, Structures• Acid Deposition is a world-wide problem

Fig. 12-17, p.338

pH is logarithmic scale. An one unit change denotes a factor of 10 difference.

pH = 5.6 for pristine rain

Fig. 12-19, p.339

Acidified Forest in Czechoslovakia

http://www.atmos.washington.edu/2005Q4/212/AcidDepositionSlides.pdf

Impact on Aquatic Organisms

http://www.epa.gov/airmarkets/acidrain/effects/surfacewater.html#fish

Sandstone Figure in Germany

1908 1968

Herr Schmidt-ThomsenHerr Schmidt-Thomsen

http://www.atmos.washington.edu/2005Q4/212/AcidDepositionSlides.pdf

Summary

• Air Pollutants – Long History– Primary: CO, NOx, SOx, VOC, PM – Secondary: H2SO4, NO2, O3

• Global Problem - Knows No Boundaries!– Serious Health Consequences

• US Air Improving - Clean Air ActBut It is Degrading in Emerging Economies

• Air Pollution Weather and Air Dispersion• Acid Rain

Next Assignments

• Next Class – Quiz #6

• Next Lecture

Topic – Ozone Depletion

Reading – Ahrens pg 324-327, 330

Problems – 12.10, 12.11