NATS 101 Lecture 31 Air Pollution Meteorology
Jan 15, 2016
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
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
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
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
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. 12-15, 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
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. 12-19, p.339
Acidified Forest in Czechoslovakia
http://www.atmos.washington.edu/2005Q4/212/AcidDepositionSlides.pdf
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