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Environment Tenth Edition

Raven

Chapter 19

Air Pollution

Overview of Chapter 19

• Types and Sources of Air Pollution

• Effects of Air Pollution

• Controlling Air Pollution in the U.S.

• Ozone Depletion in the Stratosphere

• Acid Deposition

• Air Pollution Around the World

• Indoor Air Pollution

Forest Burning in Sumatra

• Fires are set to clear forests for planting

• In S.E. Asia, agriculture and silviculture result in more air pollution than industry

• Burning results in severe air pollution and poor visibility

• Smoke is full of small particles that can lodge in lungs and cause illness/disease

Our Atmosphere

• Atmospheric Composition o Nitrogen 78.08%

o Oxygen 20.95%

o Argon 0.93%

o Carbon dioxide 0.04%

• Ecosystem services o Blocks UV radiation

o Moderates the climate

o Redistributes water in the hydrologic cycle

Air Pollution

• Chemicals added to the atmosphere by natural events or human activities in high enough concentrations to be harmful

• Two categories: o Primary Air Pollutant

• Harmful substance emitted directly into the atmosphere

o Secondary Air Pollutant • Harmful substance formed in the atmosphere when a

primary air pollutant reacts with substances normally found in the atmosphere or with other air pollutants

Major Air Pollutants (1 of 2) Table 19.1 Major Air Pollutants

Pollutant Composition Primary or Secondary Characteristics

Particulate Matter Blank Blank Blank

Dust Variable Primary Solid particles

Lead Pb Primary Solid particles

Sulfuric acid H2SO4 Secondary Liquid droplets

Nitrogen Oxides Blank Blank Blank

Nitrogen dioxide NO2 Primary Reddish-brown gas

Sulfur Oxides Blank Blank Blank

Sulfur dioxide SO2 Primary Colorless gas with strong odor

Carbon Oxides Blank Blank Blank

Carbon monoxide CO Primary Colorless, odorless gas

Carbon dioxide* CO2 Primary Colorless, odorless gas

Major Air Pollutants (2 of 2)

Pollutant Composition Primary or Secondary Characteristics

Hydrocarbons Blank Blank Blank

Methane CH4 Primary Colorless, odorless gas

Benzene C6H6 Primary Liquid with sweet smell

Ozone O3 Secondary Pale-blue gas with acrid odor

Hazardous Air Pollutants

Blank Blank Blank

Chlorine Cl2 Primary Yellow-green gas

*Discussed in Chapter 20.

Source: Environmental Protection Agency. Compiled by authors.

Primary and Secondary Pollutants

Major Classes of Air Pollutants

• Particulate Matter

• Lead

• Nitrogen Oxides

• Sulfur Oxides

• Carbon Oxides

• Hydrocarbons

• Ozone

• Hazardous Air Pollutants (HAPs)

Particulate Matter and Lead

• PM - thousands of different solid or liquid particles suspended in air o Includes: soil particles, soot, lead, asbestos, sea salt, and

sulfuric acid droplets

o May contain materials with toxic/carcinogenic effects

o Small particles can become lodged in lungs

• Lead – soft metal used in industrial/chemical processes o Acute and chronic effects, including permanent

impairment of cognitive ability

Nitrogen and Sulfur Oxides

• Nitrogen Oxides o Gases produced by the chemical interactions between

atmospheric nitrogen and oxygen at high temperature

o Greenhouse gases that cause difficulty breathing

• Sulfur Oxides o Gases produced by the chemical interactions between

sulfur and oxygen

o Causes acid precipitation

Carbon Oxides and Hydrocarbons

• Carbon Oxides o Carbon monoxide (CO) – poisonous gas

o Carbon dioxide (CO2) – greenhouse gas

• Hydrocarbons o Diverse group of organic compounds that contain only

hydrogen and carbon (ex: CH4 - methane)

o Some are related to photochemical smog and greenhouse gases

Ozone

• Tropospheric Ozone o Man-made pollutant in the lower atmosphere

o Secondary air pollutant

o Component of photochemical smog

• Stratospheric Ozone o Essential component that screens out UV radiation in the

upper atmosphere

o Man-made pollutants (ex: CFCs) can destroy it

Ozone Damage to Grape Leaves

Air Pollutants

Sources of Outdoor Air Pollution

• Two main sources: o Transportation

o Industry

• Electric power plants and other stationary sources emit most particulate matter

Urban Air Pollution

• Industrial smog – sulfur oxides and PM o 4000 Londoners died in 1952 (+8000 within next two

months

• Photochemical smog (ex: Los Angeles below) o Brownish-orange haze formed by chemical reactions

involving sunlight, nitrogen oxide, and hydrocarbons

Formation of Photochemical Smog

Efforts to Reduce Ozone in S. California

• Volatile organic compounds (VOCs) o Contributes to smog

o Ex: compounds released from paints, cleaning products, dry cleaners, bakeries

• Temperature inversions o During inversion, temperature increases with altitude

(usually reverse)

o Pollution is trapped in high concentrations near surface and is not distributed

Peak Ozone in S. California

• CA consolidated efforts to improve air quality (1977)

• Improvements due to a few major regulations

Sources of Smog in Los Angeles

Effects of Air Pollution

• Low level exposure o Irritates eyes

o Causes inflammation of respiratory tract

• Can develop into chronic respiratory diseases o Emphysema

o Chronic bronchitis

Health Effects of Pollutants Table 19.2 Health Effects Of Several Major Air Pollutants Pollutant Source Effects

Particulate matter Industries, electric power plants, motor vehicles, construction, agriculture

Aggravates respiratory illnesses; long-term exposure may cause increased incidence of chronic conditions such as bronchitis; linked to heart disease; suppresses immune system; some particles, such as heavy metals and organic chemicals, may cause cancer or other tissue damage

Nitrogen oxides Motor vehicles, industries, heavily fertilized farmland

Irritate respiratory tract; aggravate respiratory conditions such as asthma and chronic bronchitis

Sulfur oxides Electric power plants and other industries

Irritate respiratory tract; same effects as particulates

Carbon monoxide Motor vehicles, industries, fireplaces

Reduces blood’s ability to transport oxygen; headache and fatigue at lower levels; mental impairment or death at high levels

Ozone Formed in atmosphere (secondary air pollutant)

Irritates eyes; irritates respiratory tract; produces chest discomfort; aggravates respiratory conditions such as asthma and chronic Bronchitis

Children and Air Pollution

• Greater health threat to children than adults o Air pollution can restrict lung development

o Children have higher breathing rate than adults

• Children who live in high ozone areas are more likely to develop asthma

Controlling Air Pollution in U.S.

• Smokestacks with electrostatic precipitator o Electrode imparts negative charge on the air pollutants

o Negatively charged pollutants are then attracted to positively charged walls- fall into collector

Smokestacks with Scrubbers

• Particulate material can also be controlled by proper land-excavating techniques o Ex: sprinkling water on dry

soil during road construction

• Cars – catalytic converters

Effect of Scrubbers

Emissions not controlled- heavily polluted (China)

Emissions controlled with scrubbers-only steam is expelled (North Carolina)

Phase I Vapor Recovery

• System for gasoline in underground tanks

The Clean Air Act

• 1955, with significant updates in 1990

• Authorizes EPA to set limits on amount of specific air pollutants

• Focuses on 6 pollutants: o lead, particulate matter, sulfur dioxide, carbon monoxide,

nitrogen oxides, and ozone

• Act has led to decreases in air pollutants o Most dramatic is lead - decreased by 98% since 1970

(due to switch to unleaded gasoline)

Emissions in the United States

Urban Areas with Worst Air Quality Table 19.3 U.S. Urban Areas With The Worst Air Quality In 1999 (Ozone Nonattainment Areas), And Conditions In The Same Locations In 2016.

BLANK 1999 2016

Los Angeles South Coast Air Basin, California Extreme Extreme

Chicago, Gary, and Lake County, Illinois–Indiana Very severe Moderate

Houston, Galveston, and Brazoria, Texas Very severe Moderate

Milwaukee and Racine, Wisconsin Very severe No longer listed

New York City, northern New Jersey, and Long Island, New York–New Jersey–Connecticut

Very severe Moderate

Baltimore, Maryland Severe Moderate

Philadelphia, Wilmington, Trenton, Pennsylvania–New Jersey–Delaware– Maryland

Severe Marginal

Sacramento, California Severe Severe

San Joaquin Valley, California Severe Extreme

Ventura County (between Santa Barbara and Los Angeles), California Severe Serious

Ozone Layer in Stratosphere

• Ozone protects Earth from UV radiation

Ozone Thinning in Stratosphere

• Ozone thinning/hole o First identified in 1985

over Antarctica

o Occurs annually between Sept. and Nov.

• Caused by human- produced bromine and chlorine containing chemicals (ex: CFCs)

Ozone Depletion in Stratosphere

• Hole over Antarctica requires two conditions: o Sunlight just returning to polar region

o Circumpolar vortex- a mass of cold air that circulates around the southern polar region

• Polar stratospheric clouds form o Enable chemical reactions that cause chlorine and

bromine to destroy ozone

Effects of Ozone Depletion

• Higher levels of UV- radiation hitting the Earth o Eye cataracts

o Skin cancer (right)

o Weakened immunity

• May disrupt ecosystems

• May damage crops and forests

Recovery of Ozone Layer

• Montreal Protocol (1987) o Reduction of CFCs

o Started using HCFCs (greenhouse gas)

• All ozone destroying chemicals phased out in most countries

• Satellite pictures in 2000 indicated that ozone layer was recovering

• Full recovery will not occur until 2050

Acid Deposition

• Sulfur dioxide and nitrogen dioxide emissions react with water vapor in the atmosphere and form acids that return to the surface as either dry or wet deposition

• PH scale

How Acid Deposition Develops

Effects of Acid Deposition

• Declining aquatic animal populations

• Thin-shelled eggs prevent bird reproduction o Calcium is unavailable in

acidic soil

• Forest decline

o Black Forest in Germany (right)

Forest Decline

Managing Acid Deposition

• Acid deposition is cross boundary issue o Pollution in one place,

problem in another

Air Pollution Around the World

• Air quality is deteriorating rapidly in developing countries o Developing countries have older cars, air quality is low

priority

• Liaoning Province, China o Residents only see sunlight a few weeks each year

Air Pollution in Beijing, New Delhi, and Mexico City

• Beijing, China and New Delhi, India have recently improved air quality

• Mexico City no longer on top ten because quality in other cities worsened

• New Delhi, India (picture)

Long Distance Transport of Air Pollutants Global Distillation Effect

Sources of Household Air Pollution

• Pollutants can be 5–100x greater than outdoors o Many spend 95% of time indoors

• Most common contaminants: o Radon, cigarette smoke, carbon monoxide, nitrogen

dioxide, formaldehyde, pesticides, lead, cleaning solvents, ozone, and asbestos

Indoor Air Pollution

Tobacco and Household Radon Infiltration • Cigarette smoke o Increasing in developing

nations

• Radon o Natural form of ionizing

radiation

o Damaging to surface tissues if not diluted with air

o Trapped in houses

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