Air and Air Pollution

The Atmosphere• Stratosphere

– 11-30 miles– Little water vapor– Ozone layer

• UV filter

• Troposphere– 11 mile at equator;

8 miles at poles– weather breeder– 78% N, 21% O– Natural heating

• Solar radiation• Greenhouse effect

The Atmosphere• Exosphere• Thermosphere

– ionosphere– aurorea borialis– hottest layer

• 1000 C

• Mesosphere– very little atmosphere– coldest layer

Atmospheric pressure (millibars)0 200 400 600 800 1,000

120

110

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90

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50

40

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0(Sea

Level)–80 –40 0 40 80 120

Pressure = 1,000millibars atground level

Temperature (˚C)

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iles)

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Thermosphere

Heating via ozone

Mesosphere

Stratosphere

Ozone “layer”

Heating from the earthTroposphere

Temperature

Pressure

Mesopause

Stratopause

Tropopause

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Ozone concentration (ppm)

Alt

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iles)Stratospheric ozone

Stratosphere

Troposphere

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Photochemical ozone

Benefical Ozone

Harmful Ozone

Air Pollution introduction of chemicals,

particulate matter, or microorganisms into the atmosphere at concentrations high enough to harm plants, animals, and materials such as buildings, or to alter ecosystems.

the presence of one or more chemicals in the atmosphere in sufficient quantities and duration to (1) cause harm to us, other forms of life, and materials, or (2) alter climate.

Major Classes of Air Pollutants• Carbon oxides

– Carbon monoxide and carbon dioxide

• Sulfur oxides– Sulfur dioxide and

sulfur trioxide• Nitrogen Oxides

– Nitric oxide, nitrogen dioxide, nitrous oxide

• Volatile Organic Compounds– Methane, propane,

CFCs

• Photochemical Oxidants– Ozone, peroxyacal nitrates (PAN),

hydrogen peroxide (H2O2)

• Suspended particulate matter (SPM)– Dust, soot, asbestos, lead, nitrate,

and sulfate salts– Sulfuric acid, PCBs, dioxins,

pesticides

• Radioactive substances– Radon-222, iodine-131,

strontium-90, plutonium-239

• Hazardous Air Pollutants (HAPS)

Criteria Air PollutantsIdentified by the Clean Air Act 1970

EPA uses six "criteria pollutants" as indicators of air quality1. Nitrogen Dioxide: NO2

2. Ozone: ground level O3

3. Carbon monoxide: CO4. Lead: Pb5. Particulate Matter: PM10 (PM 2.5) 6. Sulfur Dioxide: SO2

• Volatile Organic Compounds: (VOCs)EPA established for each concentrations above which adverse effects on health may occur

Clean Air Act http://www.epa.gov/air/oaq_caa.html

• Title I - Air Pollution Prevention and Control– Part A - Air Quality and Emission Limitations– Part B - Ozone Protection (replaced by Title VI)– Part C - Prevention of Significant Deterioration of Air Quality– Part D - Plan Requirements for Nonattainment Areas

• Title II - Emission Standards for Moving Sources– Part A - Motor Vehicle Emission and Fuel Standards– Part B - Aircraft Emission Standards– Part C - Clean Fuel Vehicles

• Title III - General• Title IV - Acid Deposition Control• Title V - Permits• Title VI - Stratospheric Ozone Protection

Nitrogen Dioxide (NO2)• Properties: reddish brown gas, formed as

fuel burnt in car, strong oxidizing agent, forms Nitric acid in air

• Effects: acid rain, lung and heart problems, decreased visibility (yellow haze), suppresses plant growth

• Sources: fossil fuels combustion, power plants, forest fires, volcanoes, bacteria in soil

• Class: Nitrogen oxides (NOx) • EPA Standard: 0.053 ppm

Mobile Source Emissions: Nitrogen Oxides

Tropospheric Ozone (O3)

• Properties: colorless, unpleasant odor, major part of photochemical smog

• Effects: lung irritant, damages plants, rubber, fabric, eyes,

• Sources: Created by sunlight acting on NOx and VOC , photocopiers, cars, industry, gas vapors, chemical solvents, incomplete fuel combustion products

• Class: photochemical oxidants

Ozone (O3)

• 10,000 to 15,000 people in US admitted to hospitals each year due to ozone-related illness

• Children more susceptible– Airways narrower– More time spent outdoors

Mobile Source Emissions: Hydrocarbons – Precursors to Ozone

Carbon Monoxide (CO)• Properties: colorless, odorless, heavier than air,

0.0036% of atmosphere• Effects: binds tighter to Hb than O2, mental

functions and vision, even at low levels• Sources: incomplete combustion of fossil fuels

60 - 95% from auto exhaust• Class: carbon oxides (CO2, CO)• EPA Standard: 9 ppm • 5.5 billion tons enter atmosphere/year

Mobile Source Emissions - CO

Lead (Pb)• Properties: grayish metal• Effects: accumulates in tissue; affects

kidneys, liver and nervous system (children most susceptible); mental incapacitation; possible carcinogen

• Sources: particulates, smelters, batteries• Class: toxic or heavy metals• EPA Standard: 1.5 ug/m3

• 2 million tons enter atmosphere/year

Suspended Particulate Matter (PM10) •Properties: particles suspended in air (<10 um)

•Effects: lung damage, mutagenic, carcinogenic, teratogenic

•Sources: burning coal or diesel, volcanoes, factories, unpaved roads, plowing, lint, pollen, spores, burning fields

•Class: SPM: dust, soot, asbestos, lead, PCBs, dioxins, pesticides

•EPA Standard: 50 ug/m3 (annual mean)

Mobile Source Emissions: Fine Particulate Matter (PM2.5)

Sulfur Dioxide (SO2) • Properties: colorless gas with irritating odor• Effects: produces acid rain (H2SO4), breathing

difficulties, eutrophication due to sulfate formation, lichen and moss are indicators

• Sources: burning high sulfur coal or oil, smelting or metals, paper manufacture

• Class: sulfur oxides• EPA Standard: 0.3 ppm (annual mean)• Combines with water and NH4 to increase soil

fertility

VOCs (Volatile Organic Compounds)• Properties: organic compounds (hydrocarbons) that

evaporate easily, usually aromatic • Effects: eye and respiratory irritants; carcinogenic; liver,

CNS, or kidney damage; damages plants; lowered visibility due to brown haze; global warming

• Sources: vehicles (largest source), evaporation of solvents or fossil fuels, aerosols, paint thinners, dry cleaning

• Class: HAPs (Hazardous Air Pollutants) – Methane– Benzene– Chlorofluorocarbons (CFCs), etc.

• Concentrations indoors up to 1000x outdoors• 600 million tons of CFCs

Types of Pollutants Primary pollutants- polluting compounds

that come directly out of the smoke-stack, exhaust pipe, or natural emission source.

Examples: CO, CO2, SO2, NOx, and most suspended particulate matter.

Secondary Pollutants - pollutants that have undergone transformation in the presence of sunlight, water, oxygen, or other compounds.

Examples: ozone, sulfate and nitrate

Photochemical Reaction• any chemical reaction activated by light

Photochemical Smog– a mixture of primary and secondary pollutants

formed under the influence of sunlight

Brown Air Smog(N2 + O2 ---> 2NO) high temps

(2NO + O2 ---> 2NO2)

NO2 (yellowish brown gas)

Photochemical Smog

Industrial Smog

• Gray Smog– Comes from

burning coal

Sulfur Dioxide Sulfuric Acid

Particulates• Unburned Carbon

Fig. 17-8 p. 426Fig. 17-8 p. 426

Thermal Inversions

Thermal Inversion- when a relatively warm layer of air at mid-altitude covers a layer of cold, dense air below.

The warm inversion layer traps emissions that then accumulate beneath it.

Temperature Inversions

Subsidence inversion Subsidence inversionFig. 17-9 p. 427Fig. 17-9 p. 427

Temperature Inversions

Radiation inversion Radiation inversion

Inversion layer

Mountainrange

Sea breeze

Descending warm air mass

Decreasing temperature

Incr

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Acid Deposition Acid deposition- occurs when

nitrogen oxides and sulfur oxides are released into the atmosphere and combine with atmospheric oxygen and water. These form the secondary pollutants nitric acid and sulfuric acid.

Secondary pollutants further break down into nitrate and sulfate which cause the acid in acid deposition.

Acid Deposition

Effects of Acid Deposition

Lowering the pH of lake water Decreasing species diversity of

aquatic organisms Mobilizing metals that are found in

soils and releasing these into surface waters

Damaging statues, monuments, and buildings

Ways to Prevent Air Pollution

Removing sulfur dioxide from coal by fluidized bed combustion

Catalytic converters on cars Scrubbers on smoke stacks Baghouse filters Electrostatic precipitators

Stratospheric Ozone The stratospheric ozone layer exists roughly 45-

60 kilometers above the Earth. Ozone has the ability to absorb ultraviolet

radiation and protect life on Earth.

Formation and Breakdown of Ozone

First, UV-C radiation breaks the bonds holding together the oxygen molecule )2, leaving two free oxygen atoms: O2 + UV-C -> 2O

Sometimes the free oxygen atoms result in ozone: O2 + O -> O3

Ozone is broken down into O2 and free oxygen atoms when it absorbs both UV-C and UV-B ultraviolet light: O3 + UV-B or UV-C -> O2 + O

Depletion of the Ozone Layer

Global Ozone concentrations had decreased by more than 10%.

Depletion was greatest at the poles Decreased stratospheric ozone has

increased the amount of UV-B radiation that reaches the surface of Earth.

Montreal Protocol- international agreement to reduce CFC’s.

Indoor Air PollutionSick Building Syndrome

Fig. 17-17p. 434

Sick Building Syndrome

• A persistent set of symptoms in > 20% population

• Causes(s) not known or recognizable• Complaints/Symptoms relieved after exiting

building

Complaints/Symptoms

• Headaches• Fatigue• Reduced Mentation• Irritability • Eye, nose or throat

irritation

• Dry Skin• Nasal Congestion• Difficulty Breathing• Nose Bleeds• Nausea

Building Related Illness• Clinically Recognized Disease• Exposure to indoor air pollutants• Recognizable Causes

Clinically Recognized Diseases

–Pontiac Fever – Legionella spp.–Legionnaire's Disease–Hypersensitivity Pneumonitis–Humidifier Fever–Asthma–Allergy–Respiratory Disease

• Chronic Obstructive Pulmonary Disease

Sources of Indoor Air Pollutants• Building materials• Furniture• Furnishings and fabrics• Glues• Cleaning products• Other consumer products• Combustion appliances (cookers and heaters)• Open fires• Tobacco smoking• Cooking• House dust mites, bacteria and moulds• Outdoor air

Important Indoor Air pollutants• Nitrogen dioxide• Carbon monoxide• Formaldehyde• Volatile Organic Compounds (VOCs)• House dust mites (and other allergens, e.g. from pets)• Environmental tobacco smoke• Fine particles• Chlorinated organic compounds (e.g. pesticides) • Asbestos and man-made mineral fibres • Radon

Most dangerous indoor pollutants

1. Cigarette smoke2. Formaldehyde3. Radon-222 gas

Radon

• Radon-222• Associated with

uranium (U-238) and organic material in rocks

• 2nd leading cause of lung cancer

• 4 picocuries– EPA proposed

standard

Fig. 17-18p. 436

Effects of Air Pollution on Living Organisms and Materials

Damage to mucous membranes Damage to mucous membranes

Respiratory diseases

• Lung cancer• Asthma – allergic reaction• Chronic bronchitis – persistent inflammation• Emphysema – irreversible damage

Respiratory diseases

• Lung cancer• Asthma – allergic reaction• Chronic bronchitis – persistent inflammation• Emphysema – irreversible damage

Nasal cavity

Oral cavity

Pharynx (throat)

Trachea (windpipe)

Bronchus

Right lung

Bronchioles

(see figure 17.18b)

(see figure 17.18c)

Epithelial cell

Cilia

Mucus

Bronchiole

Alveolar duct

Alveoli

Alveolar sac(sectioned)

Reducing IndoorAir Pollution