Air Pollution Chapter 18

Core Case Study: South Asia’s Massive Brown Cloud Asian Brown Cloud Causes- Dust, smoke ash from drought and clearing/burning forests Acidic compounds from burning coal, diesel and other fossil fuels, soot, toxic metals organic compounds and fly ash Areas impacted-India, Bangladesh, industrial China, open sea east of the area Air pollution connects the world--pollution is tracked to other parts of world

18-1 What Is the Nature of the Atmosphere? Concept 18-1 The atmosphere is structured in layers, including the troposphere, which supports life, and the stratosphere, which contains the protective ozone layer. Atmosphere varies in Temperature Density- most dense at ground level Atmospheric pressure-decreases with altitude Layers of Atmosphere Troposphere Mesophere Stratosphere Thermosphere

Natural Capital: The Earth’s Atmosphere Is a Dynamic System with Four Layers

Layers of the Atmosphere (1) Troposphere 75–80% of the earth’s air mass Closet to the earth's surface Chemical composition of air Rising and falling air currents: weather and climate Involved in chemical cycling Stratosphere Similar composition to the troposphere, with 2 exceptions Much less water O3, ozone layer, filters UV Location

Layers of Atmosphere (2) Mesosphere 48-80km (30-50 Mi) Few molecules here Temp drops with increasing altitude Thermosphere 80+ km (50+ miles) UV absorbed and converted to heat so temp increases with altitude

Greenhouse Effect

Greenhouse Gases H2O: most prevalent CO2: only 7% of CO2 comes from human activities--but we are making an impact! CH4: very potent as a gg (21x greater than CO2) 1/3 from natural sources: plants, wetlands, termites 2/3 from humans: rice paddies, landfill (decomposition), oil/gas wells, cows (belching) N2O: fertilizers, animal wastes, burning fossil fuels (270x more potent than CO2)

18-2 What Are the Major Outdoor Pollution Problems? Concept 18-2 Pollutants mix in the air to form industrial smog, mostly the result of burning coal, and photochemical smog, caused by motor vehicle, industrial, and power plant emissions.

Air Pollution Comes from Natural and Human Sources Natural sources Dust blown by wind Pollutants from wildfires and volcanoes Volatile organics released by plants Withdrawing groundwater Human sources: mostly in industrialized and/or urban areas Stationary sources Mobile sources

Case Study: Air Pollution in the Past: The Bad Old Days Discovery of fire Middle Ages Industrial Revolution London, England 1850s 1952: yellow fog Clean Air Act of 1956 United States 1948: Donora, PA; first U.S. air pollution disaster 1963: New York City Global problem

Some Pollutants in the Atmosphere Combine to Form Other Pollutants Primary pollutants: emitted directly into troposphere Secondary pollutants: React with something in troposphere to form pollutant Air quality improving in developed countries Much more needs to be done in developing countries Indoor pollution: big threat to the poor

Sources and Types of Air Pollutants

What Are the Major Outdoor Air Pollutants? (1) Carbon oxides Carbon monoxide (CO) and Carbon dioxide (CO2) Sources -car exhaust, burning forests, smoke Human health and environmental impact-impairs ability of blood to carry oxygen Nitrogen oxides (NO) and nitric acid (HNO3) Sources-auto engines, coal-burning plants, lightning (NO) Acid deposition-Forms HNO3 in air Photochemical smog-NO/HNO3 in sunlight Human health and environmental impact - irritates eyes, nose, throat, lungs, suppress plant growth Sulfur dioxide (SO2) and sulfuric acid (H2SO4) Sources- natural part of sulfur cycle, burning coal. industry Human health and environmental impact- Acid deposition, reduce visibility, aggravate breathing problems

What Are the Major Outdoor Air Pollutants? (2) Particulates- Suspended particulate matter (SPM) Fine- ave. diameter <10 micrometers Ultrafine <2.5 micrometers Sources-coal-burnign power, industry, vehicles, plowed fields, construction, smoke Human health and environmental impact- irritate lung/throat, toxins can cause mutations (lead, PCBs) Ozone (O3)- “bad” troposphere; “good” stratosphere Sources- phorochemical smog Human and environmental impact-breathing issues Volatile organic compounds (VOCs) Hydrocarbons Sources-plants, wetlands, rice paddies, landfills, cows Human and environmental impact- dizziness, death

Chemical Reactions That Form Major Outdoor Air Pollutants

Case Study: Lead Is a Highly Toxic Pollutant Does not break down in the environment Sources Human health and environmental impact Most vulnerable Reduction of lead (Pb) Unleaded gasoline Unleaded paint Still problems 2007: toys with Pb paint recalled Global ban on lead in gasoline and paint

Burning Coal Produces Industrial Smog Chemical composition of industrial smog (Gray Air Smog) Suspended particles + SO2 or H2SO4 from burning coal and oil Reduction of this smog in urban cities of the United States - rarely a problem today China and smog: Huge amounts of Ind. Smog Human deaths

How Pollutants Are Formed from Burning Coal and Oil, Leading to Industrial Smog

Sunlight Plus Cars Equals Photochemical Smog Photochemical Smog- Brown Air Smog Chemical composition: mix of primary and secondary pollutants Sources- vehicle exhaust + sun+ VOCs from trees or cars VOCs + NO2 + Heat + Sunlight yields Ground level O3 and other photochemical oxidants Aldehydes- Other secondary pollutants- Human health and environmental impact- respiratory irritation

A Model of How Pollutants That Make Up Photochemicals Are Formed

Animation: Formation of photochemical smog

Several Factors Can Decrease or Increase Outdoor Air Pollution Outdoor air pollution may be decreased by Settling of particles due to gravity Rain and snow Salty sea spray from the ocean Winds Chemical reactions Outdoor air pollution may be increased by Urban buildings Hills and mountains High temperatures Emissions of VOCs from certain trees and plants Grasshopper effect Temperature inversions

A Temperature Inversion

Animation: Thermal inversion and smog

18-3 What Is Acid Deposition and Why Is It a Problem? Concept 18-3 Acid deposition is caused mainly by coal-burning power plant and motor vehicle emissions, and in some regions, threatens human health, aquatic life and ecosystems, forests, and human-built structures. Acid deposition, acid rain Formation-SO2/NOx combine with water Local versus regional problems Taller stacks: reduce local/increase regional pollution downwind Effects of prevailing winds greater problem in East Buffers-CaCO3 soil neutralizes Less than pH 5.6 is acid; US average 4.5; Eastern forests can be 2.3

Natural Capital Degradation: Acid Deposition, Acid Rain

Current and Possible Future Acid Rain Problem Areas

Acid Deposition Has a Number of Harmful Effects Human respiratory disorders- bronchitis, asthma Aquatic ecosystems affected-kills fish (esp. below 4.5) acid shock: runoff of acid rain into water system (snow melt/spring rain) Aluminum toxicity: AL ions released into lake from soils –asphyxiate fish (causes too much mucus in gills) Release of toxic metals-—(Lead, copper) from water pipes to contaminate drinking water. Al, Pb, Cd, Hg: dissolved from soil and released: TOXIC Leaching of soil nutrients-1st can add N and S to soil to stimulate plant growth BUT then acids leach essential plant nutrients Loss of crops and trees- Weakens Trees (Synergistic Effect between acid and ozone) Damage to buildings, statues, and monuments

We Know How to Reduce Acid Deposition Prevention approaches Clean up Add lime to neutralize acidified lakes and soil Add phosphate fertilizer to neutralize acidified lakes

Active Figure: Acid deposition

Active Figure: Effect of air pollution in forests

18-4 What Are the Major Indoor Air Pollution Problems? Concept 18-4 The most threatening indoor air pollutants are smoke and soot from wood and coal cooking fires (a hazard found mostly in developing countries) and chemicals used in building materials and products.

Indoor Air Pollution Is a Serious Problem (1) Developing countries Indoor burning Poor suffer the greatest risk Developed countries Indoor air pollution is greater than outdoor air pollution Why? 11 of the common air pollutants higher inside than outside Greater in vehicles than outside Health risks magnified: people spend 70–98% of their time is indoors

Indoor Air Pollution Is a Serious Problem (2) Who are at greatest risk from indoor air pollution? Children under 5 and the elderly Sick Pregnant women People with respiratory disorders or heart problems Smokers Factory workers Four most dangerous indoor air pollutants Tobacco smoke Formaldehyde furniture stuffing, paneling, foam insulation, particleboard Radioactive radon-222 naturally occurring radioactive gas made by decay of U_238 Seeps into house through foundation from rocks Very small particles burning creates soot Developing countries: lots of indoor fires for heat, cooking Human health risks

Indoor Air Pollution Is a Serious Problem (3) Other possible indoor air pollutants Pesticide residue Pb particles Living organisms and their excrements E.g., Dust mites and cockroach droppings Airborne spores of molds and mildews Sick-building syndrome

Case Study: Radioactive Radon Gas Sources Human health risks Testing for radon Correcting a radon problem

18-5 What Are the Health Effects of Air Pollution? Concept 18-5 Air pollution can contribute to asthma, chronic bronchitis, emphysema, lung cancer, heart attack, and stroke. Respiratory system protection from air pollutants Role of cilia, mucus, sneezing, and coughing Effect of smoking and prolonged air pollution exposure Chronic bronchitis Emphysema

Air Pollution Is a Big Killer 3 Million deaths per year world-wide Mostly in Asia Main causes-indoor pollution US: Diesel fumes lead to cancer EPA: proposed stricter emission standards for diesel-powered vehicles Link between international trade and air pollution- Cargo ships: diesel fuel Premature Deaths from Air Pollution in the U.S.

18-6 How Should We Deal with Air Pollution? Concept 18-6 Legal, economic, and technological tools can help to clean up air pollution, but much greater emphasis should be focused on preventing air pollution.

Laws and Regulations Can Reduce Outdoor Air Pollution United States Clean Air Acts: 1970, 1977, and 1990 EPA National ambient air quality standards (NAAQs) for 6 outdoor criteria pollutants National emission standards for 188 hazardous air pollutants (HAPs) Toxic Release Inventory (TRI) Good news in U.S. Decrease in emissions Use of low-sulfur diesel fuel Cuts pollution Developing countries More air pollution

We Can Use the Marketplace to Reduce Outdoor Air Pollution Emission trading or cap-and-trade program Mixed reactions to program SO2 emissions down significantly NO2 will be tried in the future

Solutions: Stationary Source Air Pollution

Solutions: Motor Vehicle Air Pollution, Prevention and Cleanup

Reducing Indoor Air Pollution Should Be a Priority Greater threat to human health than outdoor pollution What can be done? Prevention Cleanup

Solutions: Indoor Pollution, Prevention and Cleanup or Dilution Greater threat to human health than outdoor pollution What can be done? Prevention Cleanup

What Can You Do? Indoor Pollution: Ways to Reduce Your Exposure

We Need to Put More Emphasis on Pollution Prevention Output approaches New shift to preventing outdoor and indoor pollution Pressure from citizens