Ch. 18 Air Pollution

Air Pollution Solids, liquids and gases present in atmosphere in high enough levels to harm humans, organisms, or materials

Layers of the Atmosphere Atmospheric pressure (millibars) Layers of the Atmosphere 200 400 600 800 1,000 120 75 Temperature 110 65 100 Layers characterized by changes in temperature which impact absorption rates of incoming solar radiation. Thermosphere 90 55 80 Mesosphere 45 70 Altitude (kilometers) Altitude (miles) 60 35 50 Stratosphere 40 25 Figure 18.3: Natural capital. The earth’s atmosphere is a dynamic system that includes four layers. The average temperature of the atmosphere varies with altitude (red line) and with differences in the absorption of incoming solar energy. Note how the atmosphere’s temperature falls and rises again twice as we move from lower to upper layers. Because the troposphere receives most of its heat from the earth’s surface, it cools as its air gets further from the surface. Most ultraviolet radiation from the sun is absorbed by ozone, found primarily in the stratosphere’s ozone layer, 17–26 kilometers (11–16 miles) above sea level. This ozone absorption causes the temperature to rise in the stratosphere. Question: Why do you think most of the planet’s air is in the troposphere? 30 15 Ozone layer 20 10 Troposphere 5 Pressure (Sea level) –80 –40 0 40 80 120 Temperature (˚C) Fig. 18-3, p. 467

Troposphere Where weather occurs “air” collects photochemical ozone

Stratosphere Contains O3 concentrations Referred to as ozone layer Ozone acts as UV filter

Altitude (kilometers) Ozone concentration (ppm) 40 25 35 20 Stratosphere 30 Watch This Benefical Ozone 25 Stratospheric ozone 15 Altitude (kilometers) 20 Altitude (miles) 10 15 10 5 Troposphere Harmful Ozone 5 Photochemical ozone 5 10 15 20 Ozone concentration (ppm)

Air Pollution Natural Sources Human-made sources Lightning Volcanoes Wildfires Dust blown by wind Alter chem. of atm. Concentrated in urban

Air Pollution Primary Pollutants Secondary Pollutants CO CO2 NO2 SO2 CH4 and most other hydrocarbons HNO3 H2SO4 Most suspended particles H2O2 O3 PANs Most NO3– and SO42– salts Natural Source Stationary Human Source Human Source Mobile Fig. 18-5, p. 469

Pollutants Primary Pollutants Secondary Pollutants Emitted directly into the air Carbon oxides, NOx, SO2, particulate matter, hydrocarbons From reactions between primary pollutants and normal air components or other pollutants Ozone, SO3 Air quality improving in developed countries Less-developed countries face big problems Indoor pollution: big threat to the poor

Pollutants

Major Classes of Air Pollutants Carbon Oxides Carbon monoxide & carbon dioxide Sulfur Oxides Sulfur dioxide & sulfur trioxide Nitrogen Oxides Nitric oxide, nitrogen dioxide, nitrous oxide Volatile Organic Compounds (VOCs) - Methane, propane, CFCs Photochemical Oxidants ozone, peroxycal nitrates (PAN), hydrogen peroxide (H2O2) Suspended particulate matter (SPM) Dust, soot, asbestos, lead, nitrate, and sulfate salts Sulfuric acid, PCBs, dioxins, pesticides Radioactive Substances Radon-222, iodine-131, Strontium-90, plutonium-239 Hazardous Air Pollutants (HAPS)

Major Classes of Air Pollutants

Carbon Oxides Description Example Effect CO and CO2 CO ~ poisonous CO2 – colorless & odorless CO Carbon Monoxide CO2 Carbon Dioxide (93% = natural) Greenhouse Gas Global Warming Reduces bloods ability to transport oxygen

Sulfur Oxides Description Example Effect Gases produced as S + O combine at high temps SO2 Sulfur Oxide SO3 Sulfur trioxide H2SO4 Sulfuric Acid Acid rain Respiratory health problems

Nitrogen Oxides Description Example Effect Gases produced as N + O combine at high temps Nitrogen cycle NO Nitric Acid NO2 Nitrogen Dioxide (NO combine with oxygen in air) N2O Nitrous Oxide (GHG) HNO3 Nitric acid Inhibits plant growth Health problems Creates smog Creates acid rain Greenhouse gas Global warming

Volatile Organic Compounds Description Example Effect Organic compounds that exist as gases in the atmosphere or that evaporate from sources on earth Hydrocarbons from leaves Methane CH4 Benzene or other liduids used as industrial solvents or dry cleaning fluids, etc. Greenhouse gas Global warming Methane 20X more effective at warming atmosphere compared to CO2

Photochemical Oxidants OZONE O3 Description Example Effect GOOD = stratospheric, protects from radiation BAD = tropospheric, Pollutant, light + NOx + VOCs = O3 O2 + UV = O3   Ozone hole results when strat. ozone react with CFCs to produce O2 Reduces visibility Smog Health problems Greenhouse gas Global warming

Suspended Particulate Matter Description Example Effect Solid/liquid particles suspended in atm Soil, soot, lead asbestos Reduce visibility Corrodes Metals Erodes buildings Indoor air SPM = cigarettes, burning wood, charcoal, dung, and coal

Air Toxics Description Example Effect other chemicals that react with other substances to create pollutants Lead Chlorine HCl Acid Fluorides Radioactive substances Long-term health effects

Effects of Air Pollution Respiratory Health Reduced Visibility Corrodes Material Reduces Crop Productivity Acid Rain Global Climate Change Stratospheric Ozone Depletion Health effects worse for children

Premature Deaths from Air Pollution in the U.S. Figure 18.22: This map shows the distribution of premature deaths from air pollution in the United States, mostly from very small, fine, and ultra-fine particles added to the atmosphere by coal-burning power plants. Questions: Why do the highest death rates occur in the eastern half of the United States? If you live in the United States, what is the risk at your home or where you go to school? (Data from U.S. Environmental Protection Agency) Fig. 18-22, p. 485

Lead Pollutant found in air, water, soil, plants & animals. Does not break down Indestructible and potent neurotoxin harms nervous system

Chemical Reactions

China and Smog Oct. 21, 2013