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Outdoor Air Pollution

AP Environmental Science

Mr. GrantLesson 46

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Do you know your stuff?What is the most common gas in the atmosphere?Charles

What role does ozone play in the stratosphere?David… in the troposphere?

Trade winds blow which way?Emma

Explain atmospheric convection.Wilson

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Objectives:

• Define the term Montreal Protocol.

• Identify major pollutants, outline the scope of outdoor air pollution, and assess potential solutions.

• Explain stratospheric ozone depletion and identify steps taken to address it.

• Define acidic deposition and illustrate its consequences.

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Montreal Protocol

Define the term Montreal Protocol.

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Identify major pollutants, outline the scope of outdoor air pollution and assess potential solutions.• Natural sources such as windblown dust, volcanoes, and fires

pollute the atmosphere, but human activity can worsen some of these phenomena.

• Human-emitted pollutants include primary and secondary pollutants from point and non-point sources.

• To safeguard public health under the Clean Air Act, the U.S. EPA and state governments monitor ambient concentrations of six criteria pollutants (carbon monoxide, sulfur dioxide, nitrogen dioxide, tropospheric ozone, particulate matter and lead).

• Agencies monitor emissions of these pollutants and of volatile organic compounds.

• Emissions in the United States have decreased substantially since the Clean Air Act of 1970, and ambient air quality is much improved in most respects.

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Identify major pollutants, outline the scope of outdoor air pollution and assess potential solutions.

• Emissions of 188 toxic air pollutants are also declining, but they still pose health risks.

• Industrializing nations such as China and India are experiencing some of the world’s worst air pollution today.

• Rural areas suffer air pollution from feedlots and other sources.

• Industrial smog produced by fossil fuel combustion is still a problem in urban and industrial areas of many developing nations.

• Photochemical smog like that which affects Los Angeles, Tehran, and other cities today is created by chemical reactions of pollutants in the presence of sunlight. It impairs visibility and human health in urban areas.

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Outdoor air pollution

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Natural sources pollute: volcanoes

Volcanoes are one source of natural air pollution, as shown by the Mount Saint Helens eruption in 1980

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Natural sources pollute: fires

In 1997, unprecedented forest fires sickened 20 million and caused a plane to crash

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Natural sources pollute: dust storms

Phoenix, Arizona, 2012

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We create outdoor air pollution

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Pollutants exert local and global effects

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Legislation addresses pollution

The Clean Air Act of 1970 / The Clean Air Act of 1990

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The EPA sets standards

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Criteria pollutants: CO and SO2

• Carbon monoxide (CO) =

• Sulfur dioxide (SO2) =

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Criteria pollutants: NO2

• Nitrogen dioxide (NO2) =

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Criteria pollutants: tropospheric ozone

• Tropospheric ozone (O3) =

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Criteria pollutants: particulate matter andlead

• Particulate matter

• Lead

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Areas in the U.S. fail air quality standards

Many Americans live in areas with unhealthy levels of criteria pollutants

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Agencies monitor emissions

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U.S. air pollutionIn 2008, the U.S. emitted 123 million tons of the six monitored pollutants

The average U.S. driver emits 6 metric tons of CO2/yr as well as other pollutants!

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We have reduced air pollution

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We reduced emissions and improved theeconomy

Coal Electrical Plant Scrubber

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Toxic substances pose health risks

• Toxic air pollutants = substances that cause: - Cancer, reproductive

defects- Neurological,

developmental, immune system, or respiratory problems

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U.S. health risks vary geographically

Nationwide cancer risks Non-cancerous respiratory ailments

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Industrializing and developing nations suffer increasing pollution

More people own cars

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Air pollution in China

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Air quality is a rural issue, too

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Smog: our most common air quality problemSmog = an unhealthy mixture of air pollutants over urban areas

Smog in Donora killed 21 people and sickened 6,000

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Photochemical (brown air) smog

High levels of NO2 cause photochemical smog to form a brown haze over cities

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Industrial smog Photochemical smog

Creation of industrial and photochemical smog

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We can reduce smog

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Explain stratospheric ozone depletion and identify steps taken to address it.• CFCs and other persistent human-made compounds destroy

stratospheric ozone, and thinning ozone concentrations pose dangers to life because they allow more ultraviolet radiation to each Earth’s surface.

• Ozone depletion is most severe over Antarctica, where an “ozone hole” appears each spring.

• The Montreal Protocol and its follow-up agreements have proven remarkably successful in reducing emissions of ozone-depleting substances.

• The long residence time of CFCs in the atmosphere accounts for a time lag between the protocol and the full restoration of stratospheric ozone.

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Synthetic chemicals deplete stratospheric ozone

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CFCs destroy ozone

One chlorine atom can destroy 100,000 ozone molecules

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The Antarctic ozone hole

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The Montreal ProtocolMontreal Protocol = 196 nations agreed to cut CFC production in half by 1998Ozone depleting Substance Consumption = Imports + production – Exports

developed Country (Article 2 Parties) (this schedule will be applicable for USA CANADA

Article 5 Parties developing Country (Mexico)

CFCs 100% phase out Jan. 1st, 1996

Base level: 1995-97Freeze in Consumption: Jan 1st, 199950% Cut-200585% Cut-2007Phase out: Jan. 1st 2010

Halons 100% phase out Jan. 1st, 1994

Base level: 1995-97Freeze in Consumption: Jan 1st, 199950% Cut-2005Phase out: Jan. 1st 2010

Methyl Bromide Phase out 2005 Base level: 1995-98Freeze in Consumption: Jan 1st, 200120% Cut-2005Phase out: Jan. 1st 2015

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Protecting the ozone layer

International agreements reduced ozone-depleting substances

The hole in the ozone has stopped growing

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Define acidic deposition and illustrate its consequences.• Acidic deposition results when pollutants such as SO2 and

NO react in the atmosphere to produce strong acids that are deposited on Earth’s surface.

• Acidic deposition may be wet (e.g., “acid rain”) or dry, and it may occur a long distance from the source of pollution.

• Water bodies, soils, trees, animals, and ecosystems all experience negative impacts from acidic deposition.

• Regulation, cap-and-trade programs, and technology are all helping to reduce acid deposition in North America, yet more needs to be done, and industrializing nations will need to tackle the problem as well.

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Acid deposition… another transboundary issue

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Burning fossil fuels produces acid rain

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Impacts of acid deposition

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pH of precipitation in the U.S.

Many regions of acidification are downwind of major sources of pollution

• The acid-neutralizing capacity of soil, rock, or water impacts the severity of acid rain’s effects

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We have begun to address acid deposition