Chapter 12: Air12-1 What Causes Air Pollution

Air Pollution: when harmful substances build up in the air to unhealthy levels (solids, liquids, gasses)

• Most comes from human activities (vehicles and industry)

Primary Pollutants: a pollutant that is put directly into the air by human activity

Pollutant Description Primary Sources Effects

Carbon Monoxide (CO)

Odorless, colorless Cars, trucks, buses, small engines, some industrial processes

Interferes w/ blood’s ability to carry oxygen, slowing reflexes, causing drowsiness, can cause death

Nitrogen Oxides

Burning fuels in vehicles, power plants, industrial boilers

Can make body vulnerable to respiratory infections, lung diseases and cancer. Contributes to brownish haze over cities and acid precipitation.

Sulfur Dioxide (SO2)

Burning fossil fuels Acid precipitationReacts with other substances to form secondary pollutants that can harm plant life and irritate human respiratory system.

Volatile Organic Compounds (VOCs)

Chemicals that vaporize readily and form toxic fumes

Burning fuels (vehicles are a major source)

Contribute to smog formation.Can cause serious health problems, cancer.May harm plants

Particulate Matter (particulates)

Tiny particles of liquid or solid matter

Construction, agriculture, forestry, and fires.Vehicles and industrial processes.

Can form clouds that reduce visibility and cause a variety of respiratory problems.Linked to cancer.May corrode metals and erode buildings and sculptures.

Secondary Pollutants: formed when a primary pollutant reacts with other primary pollutants or with naturally occurring substances (like water)

• Ex. Ground-level Ozone = vehicle exhaust + UV rays + Oxygen

Motor Vehicle Emissions• The Clean Air Act (1970, strengthened in 1990)• EPA can regulate vehicle emissions in the U.S.• Gradually eliminated lead in gasoline (reduced lead

pollution more than 90%!)• Catalytic Converters (required in vehicles) clean

exhaust gases of pollutants before they leave the tailpipe

• EPA estimates that cars and trucks have 95% fewer emissions than 30 yrs. Ago

California Zero-Emission Vehicle Program• In 1990 CA established a program to require 16% of

all vehicles sold in CA to be zero-emissions vehicles (ZEVs) by 2016– No tailpipe emissions / No emissions from gasoline

• Electric Vehicles were becoming increasing available, and charging stations were becoming more common in parking lots.

• Who Killed the Electric Car?– Car Manufacturers and the Bush Administration sued CA in

2003. – The revised program has been severely watered down.– As a result, electric car production was virtually stopped.

Industrial Air PollutionClean Air Act - many industries must

use scrubbers or other pollution-control devices.

• Scrubber: machine that removes many pollutants from emissions by spraying gases with water.

• Clear Skies Initiative – check it out• Smog: when air pollution hangs over

urban areas and reduces visibility (vehicles & industry are main causes)

• Sun +Air+Vehicle Exhaust+Ozone

Directing Traffic With a Smog Mask in Bangkok, Thailand

Temperature Inversions• Normal Conditions – air temp. decreases

w/ height– Warm air near the surface (carrying pollution)

is less dense and tends to rise until it finds air of the same temp/density

– Usually carries pollution up & away

Temperature InversionsTemperature Inversions – colder air near

the surface with warmer air above– Cold air near the surface is warmer and more

dense – so it resists rising– This “traps” pollutants near earth’s surface

Temperature Inversions – Why?

• On a clear night, when the earth's surface radiates heat away rapidly.  If the air is clear, the ground, and the air directly above it, can be cooler than the air at higher altitudes.

• Air blowing in from cold water to a coastal area.• At night in valleys, when cold, dense air flows

downslope under the influence of gravity, draining off the slopes and uplands, and into the valleys.  The air in the valley bottoms is colder than the air above. 

12-2 Air, Noise, and Light Pollution

Health Effects of Air Pollution

– children and elderly are particularly sensitive

Short-Term Health Effects of Air Pollution• Headache; nausea; irritation to eyes, nose, and

throat; tightness in the chest; coughing; upper respiratory infections (bronchitis, pneumonia)

Long-Term Health Effects of Air Pollution• Emphysema, lung cancer, heart disease

Indoor Air Pollution

• The air indoors may be more polluted than the air outside.

• Major Sources of indoor air pollution: Plastics, cleaning chemicals, building materials

• Sick-Building Syndrome: buildings that have very poor air quality

» Common in hot places where building are tightly sealed to keep out the heat

Radon Gas

• Colorless, tasteless, odorless, and radioactive

• Produced by decay of uranium (occurs naturally in Earth’s crust)

• Seeps through cracks and holes in foundation into buildings

• Adheres to dust particles enters lungs• 2nd leading cause of lung cancer in the

U.S.

Asbestos• Minerals that form in long, thin

fibers• Strong and resistant to heat• Used mainly as insulation and

fire retardant• Banned in U.S. in early 70’s• Inhaled can cut and scar

lungs causes asbestosis– Difficulty breathing, maybe

eventual death from heart failure

• Billions spent to remove asbestos from schools

Noise Pollution• Unnecessary sound of any kind.

• Ex. airplanes, construction equipment, city traffic, factories, appliance, lawnmowers

• Problems: loss of hearing, high blood pressure, stress, loss of sleepdecreased productivity

• Decibels (dB): unit for measuring sound

Light Pollution

• Inefficient lighting in urban areas diminishes our view of the night sky and wastes energy.

• No direct hazard to human health• Ex. billboards lit from below, lighting of building

exteriors, poor-quality street lights• Solutions: shield light so it is directed

downward; timers, light or motion sensors (use light only when needed); using energy efficient lighting

12-3 Acid Precipitation

Acid Precipitation: rain, sleet, snow that contains a high concentration of acids.

• Sulfur oxides and nitrogen oxides (from burning fossil fuels) combine with water in the atmosphere to form sulfuric and nitric acids. Precipitation (rain, sleet, snow) that contains these acids is called acid precipitation.

• SO2 + O2 = SO3 + H2O = H2SO4

• NO + O2 = NO2+ H2O = HNO3

pH

• Pure Water = 7.0

• Normal Precipitation = 5.6

• Acid Precipitation <5.0– Eastern Europe 4.3-4.5– U.S. 4.2-4.8

Acidification: increase in the concentration of acid• Causes Changes Soil Chemistry:

– Some nutrients are dissolved and washed away

– Aluminum and other toxic metals may be released and absorbed by plants

– Aluminum causes root damage– Sulfur dioxide causes clogs the openings on

the surfaces of plants

Acid Shock: when a sudden influx of acidic water enters a lake or stream and causes a rapid change in pH that harms aquatic life.

– Causes large numbers of fish to die– Affects the reproduction of fish and

amphibians

Acid Precipitation and Humans

• Toxic metals (i.e. aluminum, mercury) can be released into the environment from the soilthen into crops, water, fishpoison the human body

• May be linked to increased respiratory problems.• Negative for commercial & sport-fishing.• Forestry (trees damaged)• Can dissolve calcium carbonate in building

materials like concrete, limestone, marble.

International Conflict and Cooperation

• Pollutants released in one geographical area may fall to the ground hundreds of kilometers away as acid precipitation – sometimes in another country.

• Canada-U.S. Air Quality Agreement: both countries agreed to reduce acidic emissions that flowed across the border.