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ATMOSPHERE AND AIR POLLUTION

Lecture 15

WHY IS THE ATMOSPHERE SO IMPORTANT?

WHAT IS THE NATURE OF THE ATMOSPHERE?

Atmosphere: Thin layers of gases surrounding the earth

Layers defined largely by differences in temperature

Innermost layers of the atmosphere: Troposphere Supports life

Stratosphere Contains the protective ozone layer

THE ATMOSPHERE CONSISTS OF SEVERAL LAYERS

Density and pressure play major roles in weather

Density• Number of gas molecules per unit of air volume• Decreases with higher altitude

Atmospheric pressure• Measure of the weight of molecules above you (Force per unit area of a column of air)• Decreases with higher altitude

AIR MOVEMENT AND CHEMICALS IN THE TROPOSPHERE AFFECT THE EARTH’S WEATHER AND CLIMATE

Troposphere 75–80% of the earth’s air mass Closest to the earth’s surface

Two primary gas types Permanent

Oxygen and Nitrogen

Variable Water Vapor Carbon Dioxide

Permanent gases make up over 95% of total atmosphere

THE STRATOSPHERE IS OUR GLOBAL SUNSCREENStratosphere: 17–48 kilometers above the earth’s surface Similar composition to troposphere except: Higher concentration of ozone (O3)

Ozone layer Filters 95% of harmful UV radiation Allows life to exist on land

WATER H2O, THE MOST IMPORTANT VARIABLE GAS

0-4% in atmosphere

Varies with temperature and location

Greenhouse Gas (GHG)

Only GHG which absorbs both incoming and outgoing radiation

CARBON DIOXIDE CO20.04% concentration

Seasonably Variable

GHG

Natural and Human produced

Absorbs outgoing radiation

WHAT IS THE GREENHOUSE EFFECT AND HOW DOES IT WORK?

GREENHOUSE EFFECT

Natural process which enables life on Earth

Earth thermal radiation held in by greenhouse gases

Atmospheric blanket

AIR POLLUTION COMES FROM NATURAL AND HUMAN SOURCES

Natural sources Wind-blown dust Pollutants from wildfires or volcanic

eruptions Volatile organics released by plants

Human sources Mostly in industrialized and urban areas Stationary sources Power plants and industrial facilities

Mobile sources Motor vehicles

AIR POLLUTANTS

Air pollution–presence of chemicals in the atmosphere Concentrations high enough to harm

organisms, ecosystems, human-made materials, or alter climate

Primary pollutants Emitted directly into the air

Secondary pollutants Formed from reactions of primary

pollutants

ATMOSPHERIC BROWN CLOUDS

Atmospheric brown clouds Particles of dust, smoke, ash, soot Caused by wind erosion, fire Found throughout Asia and the western Pacific

Pollutions travels to remote areas Absorbed into glaciers

MAJOR OUTDOOR AIR POLLUTANTS

Carbon oxides Carbon monoxide (CO) and carbon

dioxide (CO2) Some sources of CO are cars, burning

forests and grasslands, and fossil fuel burning power plants Some sources of CO2 include natural

carbon cycle and burning of fossil fuels

MAJOR OUTDOOR AIR POLLUTANTS

Nitrogen oxides and nitric acid Nitrogen dioxide (NO2 ) reacts with

water vapor in atmosphere to form nitric acid and nitrate salts, part of acid deposition Some sources are fertilizer and burning

of fossil fuels NO and NO2 play a role in the

formation of photochemical smog, a mixture of chemicals formed under the influence of sunlight in cities with heavy traffic. Nitric acid HNO3 , secondary pollutant

and a major component of acid rain.

MAJOR OUTDOOR AIR POLLUTANTS

Sulfur dioxide and sulfuric acid One-third of sulfur dioxide and sulfuric acid are from

natural sources, such as volcanoes Other sources include combustion of coal and oil

refining Reduce visibility and aggravate breathing problems,

damage crops, corrode metals, and damage stone

MAJOR OUTDOOR AIR POLLUTANTS

Particulates Suspended particulate matter (SPM)–

variety of solid particles and liquid droplets that are small and light enough to remain suspended in the air for long periods About 62% of the SPM in outdoor air

comes from natural sources such as dust, wildfires, and sea salt The other 38% comes from human

sources, such as coal-burning power and industrial plants

MAJOR OUTDOOR AIR POLLUTANTS

Ozone

•One of the major ingredients of photochemical smog

•Can cause coughing and breathing problems

•Ozone in the troposphere can be harmful at high enough levels and ozone in the stratosphere is beneficial because it protects us from harmful UV radiation

•Human activities have decreased the amount of beneficial ozone in the stratosphere and increased the amount of harmful ground-level ozone

MAJOR OUTDOOR AIR POLLUTANTS

Volatile organic compounds (VOCs) Organic compounds that exist as gases

in the atmosphere or that evaporate from sources on the Earth’s surface into the atmosphere Example: Methane from rice paddies,

landfills, natural gas wells and pipelines, and from cows

LEAD: A HIGHLY TOXIC POLLUTANT

In air, water, soil, plants, and animals

Does not break down in the environment

Impacts human health and environment Children most vulnerable Can cause death, brain damage,

and paralysis

Lead exposure for adults and children working in e-waste recycling

BURNING COAL PRODUCE INDUSTRIAL SMOG

Chemical composition of industrial smog Sulfur dioxide, sulfuric acid, and

suspended solid particles

Combustion of coal and oil forms carbon monoxide, carbon dioxide, and soot

Common in industrialized urban areas Examples: China, India, Ukraine Beijing air quality among world’s

worst

SUNLIGHT PLUS CARS EQUALS PHOTOCHEMICAL SMOG

Photochemical smog formed under the influence of sun’s UV radiation

VOCs + NOx + heat + sunlight yields: Ground level O3 and other

photochemical oxidants Aldehydes Other secondary pollutants

SEVERAL FACTORS AFFECT LEVELS OF OUTDOOR AIR POLLUTION

Natural factors that help reduce outdoor air pollution Gravity allows particulates to

settle Rain and snow Salty sea spray from the ocean Winds Natural chemical reactions

remove some pollutants

SEVERAL FACTORS AFFECT LEVELS OF OUTDOOR AIR POLLUTION

Factors that increase outdoor air pollution Urban buildings Hills and mountains High temperatures VOC emissions from certain trees

and plants The grasshopper effect Temperature inversion Warm air above cool air prevents mixing

ACID DEPOSITION

Human-generated NOx and SOx in the atmosphere

Wet deposition Acidic rain, snow, fog, or cloud vapor

Dry deposition Acidic particles

Substances remain in the atmosphere for 2–14 days

HARMFUL EFFECTS OF ACID DEPOSITION

Contributes to respiratory disorders

Releases toxic metals from soils and rocks Bioaccumulation in fish

Lowers pH in aquatic ecosystems

Leaches soil nutrients

Damages forests

Damages statues and buildings

INDOOR AIR POLLUTION IS A SERIOUS PROBLEMLess-developed countries Indoor burning of wood, charcoal, dung, crop

residues, and coal Greatest risk to low-income populations

More-developed countries Tobacco smoke Formaldehyde Radioactive radon-222 gas

HEALTH EFFECTS OF AIR POLLUTION

Air pollution can contribute to Asthma Chronic bronchitis Emphysema Lung cancer Heart attack Stroke

YOUR BODY’S NATURAL AIR POLLUTION DEFENSES CAN BE OVERWHELMED

125,000 people develop cancer in the United States each year from breathing diesel fumes

14% of the U.S. population exposed to excessive particulate pollution levels daily

LAWS AND REGULATIONS CAN REDUCE OUTDOOR AIR POLLUTION United States Clean Air Acts: 1970, 1977, and 1990 created regulations enforced by states and cities

EPA Established air quality standards for six outdoor pollutants Carbon monoxide, nitrogen dioxide, sulfur dioxide, suspended particulate matter, ozone, and lead

LAWS AND REGULATIONS CAN REDUCE OUTDOOR AIR POLLUTION

EPA’s national emission standards for 188 hazardous air pollutants (HAPs) mostly includes VOC’s, organic hydrocarbons and toxic metals Toxic Release Inventory (TRI) (1990) requires factories, power plants, mines and chemical manufacturers

to report their release and waste management methods.

New U.S. regulations Limit CO2 emissions from coal-fired power plants

New air quality standards in China Ban on high-sulfur, high-ash-content coal in major cities

2018: Policy changes considered by EPA likely to lead to less healthy air

USING THE MARKETPLACE TO REDUCE OUTDOOR AIR POLLUTION

Buy and sell air pollution allotments in the marketplace 1990 Clean Air Act authorized

emissions trading or cap-and-trade program Success depends on: How low initial cap is set

How often it is lowered

WAYS TO REDUCE OUTDOOR AIR POLLUTION

Technologies used on coal-burning power plants Electrostatic precipitator Wet scrubber

Motor vehicle pollution Prevention and reduction

REDUCING INDOOR AIR POLLUTION

Greater threat to human health than outdoor pollution

What can be done? Prevention Cleanup

THE USE OF CERTAIN CHEMICALS THREATENS THE OZONE LAYER

Ozone is thinning over Antarctica and the Arctic

Chlorofluorocarbons (CFCs) Persistent chemicals that attack ozone

in the stratosphere

WHY SHOULD WE WORRY ABOUT OZONE DEPLETION?

Ozone protects the earth’s surface from damaging UV radiation Human health concerns UV radiation affects plankton

REVERSING STRATOSPHERIC OZONE DEPLETION

Stop producing ozone-depleting chemicals immediately Will take at least 60 years to recover to 1980 levels

Agreements with a prevention approach Montreal Protocol Cut emissions of CFCs

Copenhagen Amendment Accelerated phase-out of CFCs

Atmosphere and Air Pollution
Why is the Atmosphere so Important?�
What Is the Nature of the Atmosphere?
The Atmosphere Consists of Several Layers
Air Movement and Chemicals in the Troposphere Affect the Earth’s Weather and Climate
The Stratosphere Is Our Global Sunscreen
Water H2O, �The Most Important Variable Gas�
Carbon Dioxide CO2
What is the Greenhouse effect and how does it work?
Greenhouse effect
Air Pollution Comes from Natural and Human Sources
Air Pollutants
Atmospheric Brown Clouds
Major Outdoor Air Pollutants
Major Outdoor Air Pollutants
Major Outdoor Air Pollutants
Major Outdoor Air Pollutants
Major Outdoor Air Pollutants
Major Outdoor Air Pollutants
Lead: A Highly Toxic Pollutant
Burning Coal Produce Industrial Smog
Sunlight Plus Cars Equals Photochemical Smog
Several Factors Affect Levels of Outdoor Air Pollution
Several Factors Affect Levels of Outdoor Air Pollution
Acid Deposition
Slide Number 26
Harmful Effects of Acid Deposition
Indoor Air Pollution Is a Serious Problem
Health Effects of Air Pollution
Your Body’s Natural Air Pollution Defenses Can Be Overwhelmed
Laws and Regulations Can Reduce Outdoor Air Pollution
Laws and Regulations Can Reduce Outdoor Air Pollution
Using the Marketplace to Reduce Outdoor Air Pollution
Ways to Reduce Outdoor Air Pollution
Reducing Indoor Air Pollution
The Use of Certain Chemicals Threatens the Ozone Layer
Why Should We Worry About Ozone Depletion?
Reversing Stratospheric Ozone Depletion