Environmental Science

Chapter 12

Air Pollution

Key Concepts

• Structure and composition of the atmosphere

• Types and origins of major outdoor air pollutants

• Two types of smog

• Acid deposition and how it can be reduced

• Harmful effects of air pollutants

• Preventing and controlling air pollution

Reminders…

• Troposphere lower atmosphere; extends from the Earth’s surface up to 11 miles high

• Stratosphere upper atmosphere; extends 11 to 30 miles above the Earth’s surface

Outdoor Air Pollution

• Def: presence of one or more chemicals in the atmosphere in sufficient quantities and duration to cause harm to humans or other living organisms

• Primary vs Secondary Pollutants– A. Primary those emitted directly into the

troposphere in a potentially harmful form – B. Secondary formed when primary pollutants

react with one another or other components of air

Primary Pollutants

Secondary Pollutants

Sources NaturalStationary

CO CO2

SO2 NO NO2

Most hydrocarbons

Most suspendedparticles

SO3

HNO3 H2SO4

H2O2 O3 PANs

Most and saltsNO3–

Mobile

SO42 –

Fig. 15-3, p. 348

Sources and Types of Air Pollutants

Outdoor Air Pollution

• Cities normally have higher air pollution than rural areas but winds can transport pollutants to these areas

• United States has government-mandated standards for maximum allowable atmospheric concentrations for six major pollutants

Acid RainPoland

Outdoor Air Pollution(Table 15-1)

• A. Carbon Monoxide– Sources: smoking/burning of fossil fuels– Health Effects: reduce ability of red blood cells to carry oxygen;

negatively impact the development of fetuses/young children; aggravate existing healthy conditions; cause headaches/nausea

• B. Nitrogen Dioxide– Sources: burning of fossil fuels– Health Effects: cause irritation/damage to lungs; increase

susceptibility to respiratory diseases; aggravate existing lung disorders such as asthma

– Environmental Effects: can form nitric acid in atmosphere which is a major component of acid rain; may reduce visibility

Outdoor Air Pollution

• C. Sulfur Dioxide – Sources: burning of fossil fuels– Health Effects: cause breathing problems and bronchitis-like

condition; aggravate asthma symptoms– Environmental Effects: can form sulfuric acid in atmosphere,

another component of acid rain

• D. Suspended Particulate Matter (SPM)– Sources: burning of fossil fuels, agriculture, unpaved roads,

construction– Health Effects: cause respiratory irritation/bronchitis; aggravate

existing respiratory conditions; lead to early death, cancer or mutations depending on chemicals contained within (ex: lead)

Outdoor Air Pollution• E. Ozone

– Sources: chemical reaction with volatile organic compounds and nitrogen oxides

– Health Effects: cause respiratory irritation; aggravate existing respiratory conditions; suppress immune system

• F. Lead– Sources: paint, metal refineries, storage batteries, leaded

gas, etc.– Health Effects: damage to brain and nervous system;

cancer; mental retardation

Smog

• Two Types:– A. Photochemical (Brown) Smog

• Pollutants formed with the aid of sunlight

• Forms when nitrogen oxides (NOx) and volatile organic compounds (VOCs) react with UV light

• Mixture of >100 chemicals but the most abundant of these is ozone (termed ground-level ozone)

Formation of photochemical smog

Animation

Los Angeles

Smog

– B. Industrial (Gray) Smog

• Consist mostly of sulfur dioxide, sulfuric acid droplets and aerosols

• Found in cities with industries that burn a lot of fossil fuels

Industrial Smog in India

Fig. 15-5, p. 351

• “Asian brown cloud” can be up to a three kilometres thick and stretches from India to Western Pacific

– Causes: • Asia's explosive industrial

development• Sources include: vehicular and

industrial emission, burning of millions of little cookers in peoples' homes, burning wood or dung

Smog

• Factors Influencing Smog Formation:1. Local Climate/Topography

2. Population Density

3. Amount of industry

4. Type of fuels consumed

So, because Florida has a low topography, good air circulation, high humidity, and lots of rain, smog is rarely a

problem here!

Air Pollution• http://www.airnow.gov

• Website depicts the air quality index (AQI) for select cities or locations throughout the United States– EPA calculates the AQI for five major air pollutants regulated by the

Clean Air Act: ground-level ozone, particle pollution (also known as particulate matter), carbon monoxide, sulfur dioxide, and nitrogen dioxide.

– Symbolized by color:0 to 50 Good Green51 to 100 Moderate YellowYellow101 to 150 Unhealthy for Sensitive Groups Orange151 to 200 Unhealthy Red201 to 300 Very Unhealthy Purple301 to 500 Hazardous Maroon

Air Quality - Florida

• Florida DEP website (www.dep.state.fl.us/Air)

– Contains air quality information for different cities and counties in Florida

– Osceola County• From 2001 to 2003 for Ozone:

– 97.6% of days were good (green)– 2.2% of days were moderate (yellow)– 0.2% of days were unhealthy for sensitive groups

(orange)

Acid Deposition• Primary pollutants are sulfur dioxide and nitrogen oxides which

can react with other atmospheric compounds to produce acidic substances that can remain in the atmosphere for up to two weeks!

• Acidic substances can descend to the Earth in two forms:– A. Wet ex: rain, snow, fog

– B. Dry shorter time frame (<3 days)

Acid deposition

pH Measurements at US Sites

Fig. 15-7, p. 354

Acid Deposition

• Effects:– 1. Respiratory problems in humans

– 2. Damages property

– 3. Lakes and Streams Acid rain causes a cascade of effects that harm or kill individual fish, reduce fish population numbers, completely eliminate fish species from a waterbody, and decrease biodiversity.

Acid Deposition

– 4. Trees acid rain causes slower growth, injury, or death of forests.

– 5. Corrosion of metals (such as bronze) and the deterioration of paint and stone (such as marble and limestone).

– 6. Reduced visibility

Tree Damage from Acid Deposition

Fig. 15-10, p. 356

Acid DepositionObviously, the best approach to reduce acid rain is to reduce

emission of the chemicals that cause it (sulfur dioxide and nitrogen oxides)

What you can do (EPA):– Turn off lights, computers, and other appliances when you're not using them – Use energy efficient appliances: lighting, air conditioners, heaters, refrigerators,

washing machines, etc. – Only use electric appliances when you need them. – Keep your thermostat at 68 F in the winter and 72 F in the summer. You can

turn it even lower in the winter and higher in the summer when you are away from home.

– Insulate your home as best you can. – Carpool, use public transportation, or better yet, walk or bicycle whenever

possible

– Buy vehicles with low NOx emissions, and maintain all vehicles well.

© 2006 Brooks/Cole - Thomson

Reduce air pollution by improving energy efficiency

Reduce coal use

Increase natural gas use

Increase use of renewable resources

Burn low-sulfur coal

Remove SO2 particulates, and Nox from smokestack gases

Remove Nox from motor vehicular exhaust

Tax emissions of SO2

Add lime to neutralizeacidified lakes

Add phosphatefertilizer to neutralizeacidified lakes

Solutions

Acid Deposition

Prevention Cleanup

Fig. 15-11, p. 357

Reducing Acid Deposition

Fig. 15-12, p. 358

Chloroform

Benzo--pyrene

Styrene

Radon-222

Methylene Chloride

Tobacco Smoke

Carbon Monoxide

Asbestos

Nitrogen Oxides

1, 1, 1-Trichloroethane

Major Indoor Air Pollutants

Particulates

FormaldehydeTetrachloro-ethylene

Para-dichlorobenzene

Indoor Air Pollution

• Most Dangerous:

– A. Formaldehyde colorless gas used in the manufacturing of many common household materials, such as furniture, drapes, plywood, and paneling

– B. Radon Gas colorless, odorless gas that is found naturally in underground deposits of minerals (e.g., uranium, phosphate) and seeps up through the soil and into homes via cracks, openings or through concrete blocks

Fig. 15-13, p. 359

Outlet vents for furnaces and dryers

Slab joints

Wood stove

Cracks in floorClothesdryerFurnace

Radon-222 gasSlab

Soil

Uranium-238

Sumppump

Cracks in wallCracks in wall

Open windowOpen window

Openingsaroundpipes

Openingsaroundpipes

Radon

Effects of Air Pollution

• Humans:– Break down natural defenses and lead to

respiratory diseases such as lung cancer, asthma, chronic bronchitis and emphysema

• Plants:– Forest diebacks (due to depletion of nutrients in

soil and increased susceptibility to pests and diseases)

– Estimated $2-6 billion in agricultural losses due to air pollution (mainly ozone)

Effects of Air Pollution

• Other:– Deterioration of paint on cars/houses– Damage to historical buildings, sculptures, etc.– Cleaning costs due to soot/other particulates

accumulating

Premature US Deaths from Air Pollution

Fig. 15-16, p. 361

Solutions

• Clean Air Acts of 1970, 1977 and 1990– Federal government established air

pollution regulations

– EPA was the agency charged with developing and enforcing air regulation standards

Solutions• Improvements still needed:

– Focus more on prevention than clean-up

– Increase fuel efficiency standards for automobiles, especially SUVs and trucks

– Better regulation of emissions from 2-cycle engines (e.g., outboard motors, jet skis, lawnmowers, chainsaws)

– Do more to decrease emission of greenhouse gases

– Indoor air pollution control

– Better enforcement

Emission Trading Policy

• Sulfur Dioxide Emissions– Each year a power plant is given a certain number

of pollution credits to emit a certain amount of sulfur dioxide.

– You can even buy credits!!!

www.epa.gov/airmarkets/

Other Solutions• Figures 15-17 through 15-21

• Individual Actions:

– Use mass transit– Bike/walk when possible– Use fuel efficient vehicles

– Don’t smoke indoors or in confined areas– Increase ventilation and intake of outside air– Install energy efficient appliances– Use less polluting substitutes for cleaning agents, paints, etc.

Outdoor

Indoor

Websites

• Some alternatives to common pesticide chemicals/cleaners: http://www.nsc.org/ehc/indoor/home.htm

• More information on air pollution: http://www.epa.gov/air/

• Facts about alternative fuels: http://www.epa.gov/otaq/consumer/fuels/altfuels/altfuels.htm

Any Questions?

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