CHAPTER 12 1 What Causes Air Pollution WARMUP

CHAPTER 12 -1 What Causes Air Pollution?

WARM-UP

LAYERS OF THE ATMOSPHERE • Four layers: • Troposphere • Stratosphere • Mesosphere • Thermosphere

TROPOSPHERE • Densest of the atmospheric layers • Almost all weather occurs here

STRATOSPHERE • Ozone layer (O 3) • Ozone absorbs UV radiation • 3 O 2 + UV 2 O 3

MESOSPHERE • Very cold! • Meteorites

THERMOSPHERE • Very high temperatures • Absorbs harmful solar radiation (X rays and gamma rays)

TEMPERATURE IN THE ATMOSPHERE

WHAT CAUSES AIR POLLUTION? • Air pollution: the contamination of the atmosphere by wastes from sources such as industrial burning and automobile exhausts. • Solids, liquids, or gases. • Most air pollution is the result of human activities

WHAT CAUSES AIR POLLUTION? • Some natural: dust, pollen, spores, and sulfur dioxide from volcanic eruptions • Condensation nuclei

CATEGORIES OF AIR POLLUTANTS • Primary pollutants • Emitted directly from natural sources or human activities • Ex. CO, CO 2, SO 2, NO 2 • Secondary pollutants • Occur when primary pollutants react with one another to form new harmful chemicals • Ex. H 2 SO 4, O 3, HNO 3

MAJOR OUTDOOR AIR POLLUTANTS • Carbon oxides: • Carbon monoxide (CO) • Harmful to human health • Vehicle exhaust • Carbon dioxide (CO 2) • Released from burning fossil fuels • Deforestation • Contributing to climate change

MAJOR OUTDOOR AIR POLLUTANTS • NOx (nitrogen oxide and nitrogen dioxide) • Nitrogen oxide (NO) • Automobile engines • Coal burning power plants • Nitrogen dioxide (NO 2) • Can form nitric acid (acid rain) • NOx play a role in the formation of photochemical smog

MAJOR OUTDOOR AIR POLLUTANTS • SOx (sulfur dioxide and sulfuric acid) • Sulfur dioxide (SO 2) • Combustion of coal • Oil refining • Sulfuric acid (H 2 SO 4) • Contributes to acid deposition

MAJOR OUTDOOR AIR POLLUTANTS • Particulates • Suspended particulate matter (SPM) – consists of a variety of solid particles and liquid droplets. Remain suspended in air. • Fine (PM – 10) • Ultrafine (PM – 2. 5) • Sources • Natural – dust, wildfires, sea salt • Human – coal burning power plants, motor vehicles

MAJOR OUTDOOR AIR POLLUTANTS

MAJOR OUTDOOR AIR POLLUTANTS • Ozone (O 3) • Major component of photochemical smog • Tropospheric ozone “bad ozone” • Volatile organic compounds (VOCs) • Hydrocarbons • Long term exposure may result in cancer

MAJOR OUTDOOR AIR POLLUTANTS

WARM UP • What is the difference between a primary and secondary air pollutant? (How are they defined? ) • Provide an example of each

SECONDARY POLLUTANT FORMATION

PRIMARY POLLUTANTS

HISTORY OF AIR POLLUTION • The world’s air quality problem is much worse today because modern industrial societies burn large amounts of fossil fuels. • Most air pollution in urban areas comes from vehicles and industry. • London Smog

MOTOR VEHICLE EMISSIONS • Almost 1/3 of our air pollution comes from gasoline burned by vehicles. • Over 90% of that mileage was driven by passenger vehicles. • The rest was driven by trucks and buses.

CONTROLLING VEHICLE EMISSIONS • The Clean Air Act (1970, strengthened in 1990) • Environmental Protection Agency (EPA) the authority to regulate vehicle emissions in the USA • Gradual elimination of lead in gasoline • Catalytic converters required in all automobiles

CONTROLLING VEHICLE EMISSIONS

CALIFORNIA ZERO-EMISSION VEHICLE PROGRAM • In 1990, the California Air Resources Board established the zeroemission vehicle (ZEV) program. • Zero-emission vehicles are vehicles that have no tailpipe emissions, no emissions from gasoline, and no emission-control systems that deteriorate over time. • By 2016, 16 percent of all vehicles sold in California are required to be zero-emission vehicles, including SUVs and trucks.

CALIFORNIA ZERO-EMISSION VEHICLE PROGRAM • ZEVs: • Electric vehicles • Hydrogen fuel cells vehicles • Hybrid-electric cars (Partial ZEV)

HOW HYDROGEN FUEL CELL WORKS • https: //www. youtube. com/watch? v=tajig. Z 2 e 6 t. Q

INDUSTRIAL AIR POLLUTION • Power plants that generate our electricity must burn fuel to generate energy • Burning fossil fuels releases huge quantities of SO 2 and NOx • Emit at least 2/3 of all SO 2 • More than 1/3 of all NOx

INDUSTRIAL AIR POLLUTION • https: //www. youtube. com/watch? v=20 Vb 6 hl. LQSg • https: //www. youtube. com/watch? v=-ZBNNcczm. DM

REGULATING AIR POLLUTION FROM INDUSTRY • The Clean Air Act requires many industries to use scrubbers or other pollution-control devices. • Scrubbers: a machine that moves gases through a spray of water that dissolves many pollutants. • Remove some of the more harmful substances • Ammonia (NH 3) & Hydrochloric Acid (HCl)

REGULATING AIR POLLUTION FROM INDUSTRY

REGULATING AIR POLLUTION FROM INDUSTRY • Electrostatic precipitators: machines used in cement factories and coal -burning power plants to remove dust particles from smokestacks. • Gas containing dust particles is blown through a chamber containing an electrical current. • An electric charge is transferred to the dust particles, causing them to stick together and to the sides of the chamber.

REGULATING AIR POLLUTION FROM INDUSTRY • The clean gas is released from the chamber and the concentrated dust particles can then be collected and removed. • Electrostatic precipitators remove 20 million tons of ash generated by coal -burning power plants from the air annually in the USA

SMOG • Smog: urban air pollution composed of a mixture of smoke and fog produced from industrial pollutants and burning fuels. • Two general types of smog • Gray-air smog (Industrial smog) • Brown-air smog (Photochemical smog)

BURNING COAL PRODUCES INDUSTRIAL SMOG • Chemical composition of industrial smog • Sulfur dioxide (SO 2), suspended particles, sulfuric acid (H 2 SO 4) • Gray-air smog • Reduction of this smog in urban cities of the United States, still a problem in China

INDUSTRIAL SMOG (GRAY-AIR SMOG)

SUNLIGHT PLUS CARS EQUALS PHOTOCHEMICAL SMOG • Photochemical Smog • Mixture of primary and secondary pollutants under the influence of Ultraviolet (UV) radiation from sun • VOCs + NO 2 + Heat + Sunlight yields • Ground level O 3 and other photochemical pollutants Exhaust from motor vehicles

PHOTOCHEMICAL SMOG IN SANTIAGO, CHILE

TEMPERATURE INVERSIONS • During the day, the sun heats the surface of the Earth and the air near the Earth. • The warm air rises through the cooler air above it and carries pollutants away from the ground, and into the atmosphere. • Sometimes pollution is trapped near the Earth’s surface by a temperature inversion.

TEMPERATURE INVERSIONS • Temperature inversion: an atmospheric condition in which warm air traps cooler air near Earth’s surface. • The warmer air above keeps the cooler air at the surface from moving upward. So, pollutants are trapped below with the cooler air.

TEMPERATURE INVERSIONS • If a city is located in a valley, it has a greater chance of experiencing temperature inversions. • Los Angeles, surrounded on three sides by mountains, often has temperature inversions.

DONORA, PA (1948)

AIR POLLUTION DATA LAB • AQI = Air Quality Index • Updated link: https: //www. epa. gov/outdoor-air-quality-data/air-data-aqi-plot • Follow the Procedure to complete the chart under the given years (1980 & 2013) • You can choose any pollutant you wish but please indicate your choices for first and second pollutant on your lab sheet chart • For each pollutant you fill in the number indicated for each pollutant on you AQI chart for good, moderate, unhealthy “sensitive”, unhealthy, & very unhealthy • Complete the analysis questions on the back of your lab sheet

WARM-UP • What is another name for gray-air smog? How does it form? • What is another name for brown-air smog? How does it form?

MATH PRACTICE