Urban Air Pollution Topics 5.6 Depletion of Stratospheric Ozone

Sub Topics Outline the overall structure and composition of the atmosphere Describe the role of the ozone in the absorption of UV radiation Explain the interaction between ozone and halogenated organic gases State the effect of UV radiation on living tissues and biological productivity 5.6.5Describe three methods of reducing the manufacture and release of ozone-depleting substances Describe and evaluate the role of national and international organizations in reducing the emissions of ozone-depleting substances.

5.7.1 state the source and outline the effect of tropospheric ozone outline the formation of photochemical smog Describe and evaluate pollution management strategies for Urban air pollution.

5.6.1 Outline the overall structure and composition of the atmosphere Troposphere Stratosphere Ozone layer GasPercentage Nitrogen78.08 Oxygen20.95 Argon0.93 Water Vapor<3.00% Carbon Dioxde345 ppmv Ozone10 ppmv CH4 (methane)1.6 ppmv N2O (nitric oxide) 350ppbv CO (carbon Monoxide) 70 ppbv CFC’s ppbv

The basics of Air pollution Air pollution– chemical or physical changes brought about by either natural processes or human activities resulting in air quality degradation. Natural Causes of Air pollution-volcanoes, dust storms, sea spray, viruses, bacteria, pollen, spores trees & vegetation (which emit VOC ’ s). Methane (2/3 ) from decaying vegetation & guts of termites & ruminant animals.

Review: Two pollutant Categories Primary pollutants – directly released from a source into the air in a harmful form. Secondary pollutants – modified to a hazardous form after they enter the air (acid rain or smog) or are formed by chemical reactions as components of the air mix & interact. Example: NOx

National Ambient Air Quality Standards Amendment of the clean air act – Primary Standards: set limits to protect public health. This include “sensitive” populations. – Secondary Standards: set limits to protect public welfare, including protection against decreased visibility, damage to animals, crops, vegetation's and buildings.

Air Quality Index (1970-today) "Good" The AQI value for your community is between 0 and 50. Air quality is considered satisfactory, and air pollution poses little or no risk. = GREEN "Moderate” 51 and 100. Air quality is acceptable; however, for some pollutants there may be a moderate health concern for a very small number of people."Moderate” 51 and 100. Air quality is acceptable; however, for some pollutants there may be a moderate health concern for a very small number of people.

"Unhealthy for Sensitive Groups” 101 and 150, members of sensitive groups may experience health effects. This means they are likely to be affected at lower levels than the general public. The general public is not likely to be affected when the AQI is in this range. = ORANGE "Unhealthy" Everyone may begin to experience health effects when AQI values are between 151 and 200. Members of sensitive groups may experience more serious health effects. = RED "Very Unhealthy” 201 and 300 trigger a health alert, meaning everyone may experience more serious health effects. = PURPLE "Hazardous" AQI values over 300 trigger health warnings of emergency conditions. The entire population is more likely to be affected. = MAROON

5.6.2 Describe the role of the ozone in the absorption of UV radiation Ozone= Good Up high, BAD nearby! Ozone in the stratosphere protects life from incoming UV radiation. UV radiation is absorbed during the formation and destruction of ozone from oxygen.

5.6.4 State the effect of UV radiation on living tissues and biological productivity What can UV do to you! It really messes up your DNA

Incidence of Melanoma, Crude Rate: Males Incidence of Melanoma, Crude Rate: Females

UV effects on Ecosystem

5.6.3 Explain the interaction between ozone and halogenated organic gases There is a “hole” in the ozone above Antarctica and the Arctic region Ozone depletion is the result of pollution

SubstanceUse/Sourcereactants Chlorofluorocarbons (CFC’s) Propellants, Styrofoam, refrigeration Release Chlorine HydrochlorofluorocarbonsTo replace CFC’cRelease chlorine, shorter lifetime Methyl BromidePesticideRelease Bromine atoms HalonsFire ExtinguishersRelease Bromine atoms Nitrogen oxides (Nox)Bacterial breakdown of nitrated in the soil (intensive farming) Jets Nox converted to NO, reacts with Ozone

What the heck are CFC’s During WWII CFC’s picked up in popularity as a flame retardant Also known as Freon. At the time did not react with any common chemical. Fire Extinguishers Used in refrigeration and air conditioning Styrofoam Aerosols

Brain break sjY&feature=kp

How CFC’s mess up the stratospheric ozone 2. Cl + O ClO + O 2 3. ClO + O Cl + O 2 1. CFC ’ s + sunlight --- Cl released It takes CFC ’ s many years to ascend to the stratosphere & once they ’ re there they can last from 50 – 100 years. One chlorine molecule has the ability to destroy 100,000 or more ozone molecules.

5.6.5Describe three methods of reducing the manufacture and release of ozone-depleting substances Reduce the demand for CFC’s – Replace CFC’s with CO2 – Use air or propane as a propellants – Recover and recycle propellants from refrigerators and air-conditioning units – Legislation to return fridges back to manufacturers – Add ozone to remove chlorine from stratosphere (really not practical)

5.6.6 Describe and evaluate the role of national and international organizations in reducing the emissions of ozone-depleting substances. United Nations Environment Programme (UNEP) – Montreal Protocol (1987)- International agreement on reduction of emission of ozone-depleting substances. – Saw a reduction in CFC – Ozone depleting substances are banned to trade across borders – LEDCs got more time to implement the treaty China and India are currently planning to reduce their levels of CFC’s

5.7.1 state the source and outline the effect of tropospheric ozone. Where is ozone good? Were is ozone bad???????

Source of Ozone near by Burning fossil fuels releases two pollutants – Hydrocarbons- b/c not all of the fuel is combusted – Nitrogen oxide- oxygen and nitrogen react due to the high temperature NO2- the brown hazy gas – When NO2 hits the sunlight NO is formed – O molecules react with oxygen to create ozone

Effect of ozone nearby Damages crops Irritates eyes Cause breathing difficulties Increase susceptibility to infection Can attack fabrics and rubber materials

Photochemical Smog

5.7.2 outline the formation of photochemical smog

Photchemical smog Formed when ozone, nitrogen oxides and gaseous hydrocarbons form vehicle exhaust interact with strong sunlight Photochemical Smog is a mixture of 100 different primary and secondary air pollutants with ozone as the main pollutant – Include VOC’s (volatile organic compounds) – PAN’s (peroxyacyl nitrates) Smog from a large city can effect the country side 150 km away

Topography and smog

Side effects of Smog

London Type smog Smog= smoke+ fog – Occurs at lower temperatures – Main components: sulfur dioxide and smoke particles from burning coal

Particulates From burning of any organic material or fossil fuel Require people to wear respiratory filters Many particulates are carcinogenic High levels in urban areas and LEDC