Chapter 17 Air and Air Pollution Quiz 1. In what layers of the atmosphere are the greatest concentrations of Ozone? 2. For each atmospheric layer you identified in #1, how does that Ozone form? 3. What are the health benefits or harm that result from Ozone in the atmosphere? 4. What is particulate pollution? 5. What type of particulate pollution is most harmful to humans? Quiz Answers 1. Troposphere and Stratosphere 2. Troposphere – ozone forms due to a reaction between NOx (which forms as a result of the combustion of fossil fuels) and hydrocarbons in the presence of UV radiation. Stratosphere – Ozone forms due to the breakdown of O2 into 2 O’s which then recombines with O2 to make O3. This reaction requires UV energy. Quiz Answers Cont. 3. Tropospheric Ozone is harmful. It is an irritant to mucus membranes Stratospheric Ozone is beneficial. It blocks 95% of UV rays which can be harmful to plant and animal cells 4. Particulate pollution consists of fine airborn dust particles. 5. The very fine particles < 10microns are most damaging to human and animal lungs. Learning Objectives Students should know: – The layers (especially the lower 2) of the atmosphere – The types and sources of outdoor air pollutants – Two types of smog – What acid deposition is and how it occurs – The effects of air pollution on environmental health – Methods to reduce and prevent air pollution Recall - Climate vs Weather Weather – The day-to-day change in atmospheric conditions on any spot on Earth Saturday was sunny, Monday it’s raining Climate – The long-term average of temperature and precipitation for a given region (average weather by season) No well defined limit Very low density High temperature due to short-wave solar radiation absorption by O, N _________________ Reduced temperature _________________ Temperature increase due to presence of good ozone ________________ Upper level Reduced temperature due to lower air density; zone with weather The Atmosphere 0.93% 0.04% Variables: 21% water Dust Ozone 78% Major Classes of Air Pollutants Carbon Oxides – CO, CO2 Sulfur Oxides – Sox Nitrogen Oxides – NOx Volatile Organics – VOC Suspended particulate matter – SPM Photochemical Oxidants – O3, PANS, H2O2 Radioactive Substances Hazardous Air Pollutants – organic solvents Ozone Focus on Ozone – Good Ozone Naturally occurring form of oxygen (O3) Occurs in the stratosphere Filters out and protects Earth from excess UV radiation from the Sun Is not a greenhouse gas or contributor to global climate change 3 O2+UV → 2O2+2O → 2O3 Ozone Depletion Ozone Focus on Ozone – Bad Ozone Forms near ground level Occurs as a result of reactions with the emissions of internal combustion engines burning hydrocarbon fuel Causes respiratory irritation, often severe reactions NOx + VOC + 3 O2+UV → 2 O3 Ground Level Ozone Formation OH + CO → H + CO2 H + O2 → HO2 HO2 + NO → OH + NO2 NO2 + UV → NO + O O + O2 → O3 (The net effect of these reactions is) CO + 2O2 → CO2 + O3 Ground Level Ozone Formation Smog Photochemical Smog – formed by the reaction between specific chemical compounds and sunlight. Brown to orange in color. Industrial Smog – results from industrial processes, typically from the burning of fossil fuels (coal, oil) and the emission of particulate matter. Grey in color. Photochemical Smog Source of pollutants – high temperature combustion of fuels in the presence of air (O2 and N2) – N2 + O2 2NO – 2NO + O2 2NO2 Nitrous Oxide Nitrogen dioxide NO2 causes the brownish/orange haze in areas with high traffic density or industrial processes, especially on sunny days Also contributes to ground-level ozone EPA Industrial Smog Rare in developed countries with emission regulations Common in developing countries which burn leaded gasoline and coal without emission controls (China Olympics problem) Mexico City – 10 million people in a high-altitude basin that has an abundance of UV and geographically limited air flow due to mountains around the city. Inversions Normal – pollutants rise up through cooler air masses and disperse into the upper atmosphere Inversion – a warm air layer is trapped between 2 cool layers. The warm air cannot move upward and forms a “cap” which traps upward moving emissions near the Earths surface instead of dispersing them. Great Smokey Mountains National Park – our most polluted national park Main pollution SOX, Ozone Source of Pollutants: Neighboring states coal-burning power plants and auto emissions Acid Deposition The combination of compounds, that in the atmosphere create dry or wet acids. Normally result from the NOx and SOx from coal-burning power plants reacting in air to form – HNO3, H2SO4, HCO3 Can be transported great distances (China to U.S.) “Burns” plant life, causes damage to structures. Acid Deposition Effects of Acid Deposition Damage to structures Alters pH of aquatic systems – Many species have limited tolerance to low pH – Lakes world-wide with limited aquatic life due to acid deposition Alters soil pH and “burns” plants – Soils may not buffer acid – Plants have leaf/needle damage that limits photosynthesis, weakens their ability to resist insects and disease Smokey Mountains Acid deposition is killing Spruce trees and other vegetation – Loss of native plant species is affecting biodiversity of both terrestrial and aquatic species Stream pH is decreasing, limiting numbers of sensitive species like salamanders, trout, and freshwater mollusks. Soils and rock have limited buffering ability Unconventional Pollutants • Unconventional Pollutants o Regulated by emission standards o Asbestos o Mercury o PCB’s o Benzene o Beryllium o Other organics o Aesthetic degradation Criteria Pollutants • Defined by U.S. Clean Air Act of 1970 • Regulated to allow maximum emission standards • • • • • • Carbon monoxide - CO Nitrogen Dioxides – NO2, Sulfur Dioxide – SO2 Particulates – by size Ozone – O3 Lead EPA Targets Greenhouse Gases CO2 Methane Nitrous Oxide(s) or NOx Hydrofluorocarbons Perfluorocarbons Sulfur hexafluoride. April 17, 2009 Indoor Air Pollution Often a greater hazard than outside air pollution Primary contaminants are: – Fine particulate – lead, other metals – Radon – naturally occurring – Pesticides – chlordane (termite) – Asbestos - insulation – Formaldehyde – glues, adhesives Solutions and change Outdoor Air Pollution – Reduce use of fossil fuels – Use low-sulfur coal and low-sulfur diesel – Increase vehicle mileage standards (fewer emissions per mile driven) – Accelerate development of sustainable, non-emission producing fuels – Increase type and amount of pollutants removed in scrubbing processes at point sources like power plants. – Decrease surface disturbance of land areas (dust, particulate) Solutions and Change Indoor Air Pollution – Eliminate indoor smoking – Change formulations to eliminate formaldehyde in adhesives. – Remediate/remove Asbestos – Install more efficient air cleaners to remove larger percentages of the particulate matter. – Better ventilation and air exchange in buildings Air Quality Laws and Options Clean Air Act (1970, 1977, 1990) – …comprehensive federal law that regulates air emissions from stationary and mobile sources. This law authorizes EPA to establish National Ambient Air Quality Standards (NAAQS) to protect public health and public welfare and to regulate emissions of hazardous air pollutants. Emission trading (cap and trade) Air Quality Monitoring
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