Air Pollution

The air we breathe Clean air consists of: Nitrogen Oxygen Very small amounts of argon, carbon dioxide and water vapor. We breathe 3,000 gallons of air each day. When harmful substances reach unhealthy levels we call this “air pollution.”

Layers of Earth’s atmosphere Troposhere: provides us with the air we breathe. Extends 7 miles high. Responsible for weather Stratosphere: 7-31 miles. Contains the ozone layer. Stratosheric ozone scatters UV radiation Mesosphere: 31-56 miles high Thermosphere: top layer, extends to 300 miles

Thermal Inversion In the troposphere warm air rises, mixes with cooler air and pollution dissipates In mountain valleys slopes block morning sun, air at ground level remains cool Warm air at altitude traps pollutants near the ground Ex: Los Angeles, Mexico City, Rio de Janeiro, Sao Paulo

The London Smog of 1952 In 1952, London abandoned their electric tramcars in favor of diesel buses. This added to pollution already coming from burning coal December 1952 was cold and foggy. The air pollution was trapped by an inversion layer above An estimated 4,000 people died from respiratory problems

Air Pollution Most air pollution is man-made. Natural air pollution includes volcanic ash, dust, pollen, and spores. Primary Pollutant: one that is put directly into the air by human activity ex. Soot, CO Secondary Pollutant: forms when two primary pollutants interact, or when one combines with a naturally occurring substance ex. ground level ozone, Sulfuric acid

The Clean Air Act (1970) The Clean Air Act gave the federal government authority to clean up air pollution. EPA set maximum limits on pollutants that can be in the air (National Ambient Air Quality Standards) EPA limits emissions from industry EPA regulates vehicle emissions and required the gradual elimination of lead from gasoline

Clean Air Act of 1990 Strengthened regulations on: Auto emisions Toxic air pollution (188 pollutants incl. mercury, benzene) Acid rain Stratospheric ozone pollution Emissions trading for SO2

Criteria Air Pollutants Carbon Monoxide Nitrogen Oxides Sulfur Dioxide (SO2) Particulate Matter Troposheric (ground level) ozone Lead

Carbon monoxide (CO) Odorless, colorless, poisonous Produced by the incomplete burning of fossil fuel Sources include vehicles, burning propane or natural gas indoors, faulty furnaces 500 Americans die each year from accidental CO poisoning Affects blood’s ability to carry oxygen.

http://www. epa. gov/cgi-bin/broker http://www.epa.gov/cgi-bin/broker?_service=data&_debug=0&_program=dataprog.dw_do_all_emis.sas&pol=225&stfips=19

Nitrogen Oxides (NOX) Foul smelling, reddish brown gas From vehicle exhausts, coal burning power plants, industry Contributes to smog and acid rain Makes your body vulnerable to respiratory disease and cancer

http://www.epa.gov/air/emissions/nox.htm

Sulfur Dioxide (SO2) Colorless gas with pungent odor Produced by interactions between sulfur and oxygen Comes from burning of coal and oil which contain sulfur Contributes to acid rain as sulfuric acid Harms plants and irritates human respiratory system

http://www.epa.gov/air/emissions/so2.htm#so2loc

Particulate Matter (PM) Particles of liquid or solid small enough to be suspended in the atmosphere Fine particles come from vehicles, coal burning power plants. Coarse particles come from cement plants, mining and agriculture Can form clouds that reduce visibility. Can cause a variety of respiratory problems and cancer.

http://www.epa.gov/air/emissions/pm.htm#pmloc

Troposheric (ground level) ozone Ozone (O3) is a gas composed of three oxygen atoms. Not usually emitted directly into the air (secondary pollutant) Created by a chemical reaction between oxides of nitrogen (NOx) and volatile organic compounds (VOC) in the presence of sunlight. O3 is unstable. It readily releases an O atom producing O2 and free O atom. Free O can damage living tissues and cause respiratory problems This is the pollutant that most often exceeds EPA NAAQS.

Ozone: good up high, bad nearby! High Altitude (stratosperic) ozone protects life on Earth from harmful UV rays. Man-made chemicals, such as CFC’s, have depleted our ozone layer. Since 1987 we have practically eliminated the use of ozone depleting substances Our ozone layer is recovering

Health Effects of Ground level ozone Airway irritation, coughing, and pain when taking a deep breath; Wheezing and breathing difficulties during exercise or outdoor activities; Inflammation, which is much like a sunburn on the skin;  Aggravation of asthma and increased susceptibility to respiratory illnesses like pneumonia and bronchitis Permanent lung damage with repeated exposures.

Lead Heavy metal found as a particulate Once found in gasoline Lead was found to enter the food chain, accumulate in tissues, causes central nervous system damage Today’s sources: industrial metal smelting Lead paint

Volatile Organic Compounds (VOC) Organic compounds that easily become toxic gas Vehicles are a major source, also found in household products (paint, varnish, dry cleaned clothing, air freshener) Contribute to smog formation Cause serious health problems including cancer

http://www.epa.gov/air/emissions/voc.htm

Air Pollution has decreased since 1970

Case Study - China China is building coal fired power plants at a rate of one each week According to the World Bank 16 of the worlds 20 cities with the worst air are in China. http://www.youtube.com/watch?v=-1DNjJd2YfA http://www.youtube.com/watch?v=GsjANjFlK0M&feature=related