Download ppt - Atmosphere and Pollution Ch. 18. Indoor air pollution can pose serious health risks, but they are risks that the individual can do much to minimize their

Atmosphere and PollutionCh. 18

Indoor air pollution can pose serious health risks, but they are risks that the individual can do much to

minimize their exposure; outdoor air pollution on the other hand can only be addressed by government

and regulation.

Guiding Questions• What is the composition,

structure, and function of the atmosphere?

• What are the major indoor and outdoor air pollutants?

• What is ozone depletion and what are the steps being taken to address it?

• How do weather and climate affect atmospheric conditions?

© 2011 Pearson Education, Inc.

The atmosphere

• Atmosphere = the thin layer of gases around Earth - Provides oxygen- Absorbs radiation and moderates climate- Transports and recycles water and nutrients

- 78% N2, 21% O2

• Human activity is changing the amount of some gases

- CO2, methane (CH4), ozone (O3)


The first two layers of the atmosphere

• Troposphere = bottommost layer (11 km [7 miles])- Air for breathing, weather- The air gets colder with altitude- Tropopause = limits mixing between troposphere

and the layer above it• Stratosphere = 11–50 km (7–31 mi) above sea level

- Drier and less dense, with little vertical mixing- Becomes warmer with altitude- Contains UV radiation-blocking ozone, 17–30 km

(10–19 mi) above sea level


Atmospheric properties

• Atmospheric pressure = the force per unit area produced by a column of air

• Relative humidity = the ratio of water vapor air contains to the amount it could contain at a given temperature - High humidity makes it

feel hotter than it really is• Temperature = varies with

location and time

Atmospheric pressure decreases with altitude


Natural sources pollute: volcanoes

• Release particulate matter, sulfur dioxide, and other gases - Can remain for months or

years• Aerosols = fine droplets of

sulfur dioxide, water, oxygen- Reflect sunlight back to

space - Cool the atmosphere and

surface

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


Natural sources pollute: fires• Fires pollute the atmosphere with soot and gases• Over 60 million ha (150 million acres) of forests and

grasslands burn per year• Human influence makes fires worse

- Fuel buildup from fire suppression, development in fire-prone areas, “slash-and-burn” agriculture

- Climate change will increase drought and fires

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


We create outdoor air pollution• Air pollution comes from mobile or stationary sources• Point sources = specific spots where large quantities of

pollutants are discharged (power plants and factories)

• Non-point sources = more diffuse, consisting of many small sources (automobiles)

• Primary pollutants = directly harmful and can react to form harmful substances (soot and carbon monoxide)

• Secondary pollutants = form when primary pollutants interact or react with components of the atmosphere - Tropospheric ozone and sulfuric acid


The EPA sets standards

• The EPA sets nationwide standards for emissions and concentrations of toxic pollutants

• States monitor air quality- They develop, implement, and enforce regulations- They submit plans to the EPA for approval

• The EPA takes over enforcement if plans are inadequate• Criteria pollutants = pollutants that pose especially

great threats to human health- Carbon monoxide, sulfur dioxide, nitrogen dioxide,

tropospheric ozone, particulate matter, lead


Criteria pollutants: CO and SO2

• Carbon monoxide (CO) = colorless, odorless gas- Produced primarily by incomplete combustion of fuel- From vehicles and engines, industry, waste

combustion, residential wood burning- Poses risk to humans and animals, even in small

concentrations

• Sulfur dioxide (SO2) = colorless gas with a strong odor

- Coal emissions from electricity generation, industry- Can form acid precipitation


Criteria pollutants: NO2

• Nitrogen dioxide (NO2) = a highly reactive, foul-smelling reddish brown gas

- Nitrogen oxides (NOx) = formed when nitrogen and oxygen react at high temperatures in engines

- Vehicles, industrial combustion, electrical utilities- Contribute to smog and acid precipitation


Criteria pollutants: tropospheric ozone

• Tropospheric ozone (O3) = a colorless gas with a strong odor- Results from interactions of sunlight, heat, nitrogen

oxides, and volatile carbon-containing chemicals- A secondary pollutant- A major component of smog - Participates in reactions that harm tissues and cause

respiratory problems- The pollutant that most frequently exceeds EPA

standards


Areas in the U.S. fail air quality standards

Many Americans live in areas with unhealthy levels of criteria pollutants


U.S. air pollution

In 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!


We have reduced air pollution

• Total emissions of the six monitored pollutants have declined 60% since the Clean Air Act of 1970- Despite increased population, energy consumption,

miles traveled, and gross domestic product


We reduced emissions and improved theeconomy• Technology and federal

policies• Cleaner-burning engines and

catalytic converters• Permit-trading programs and

clean coal technologies reduce SO2 emissions

• Scrubbers = chemically convert or physically remove pollutants before they leave smokestacks

• Phaseout of leaded gasoline


Industrializing nations suffer increasing pollution

• Outdoor pollution is getting worse in developing nations• Factories and power plants pollute

- Governments emphasize economic growth, not pollution control

• People burn traditional fuels (wood and charcoal)- And more own cars

• China has the world’s worst air pollution- Coal burning, more cars, power plants, factories- Causing over 300,000 premature deaths/year


Pollution in developing nations is high

More people own cars Smog in Beijing surrounds an Olympic stadium


Smog: our most common air quality problem

• Smog = an unhealthy mixture of air pollutants over urban areas

• Sulfur in burned coal combines with oxygen to form sulfuric acid

• Industrial (gray air) smog = industries burn coal or oil- Regulations in developed

countries reduced smog• Coal-burning industrializing

countries face health risks- Coal and lax pollution control

Smog in Donora killed 21 people and sickened 6,000


Photochemical (brown air) smog• Produced by a series of reactions

- Formed in hot, sunny cities surrounded by mountains• Light-driven reactions of primary pollutants and

atmospheric compounds- Morning traffic releases NO and VOCs- Irritates eyes, noses, and throats

• Los Angeles smog kills 3,900/year and costs $28 billion/year

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


Industrial smog Photochemical smog

Creation of industrial and photochemical smog