Air Pollution and Stratospheric Ozone Depletion Chapter 15

Air Pollution “introduction of chemicals, particulate matter (PM), or microorganisms into the atmosphere at concentrations high enough to harm plants, animals, and materials such as buildings or alter ecosystems” “pollution of troposphere” or “ground-level pollution” It can occur naturally from things like volcanoes and fires or it can be anthropogenic In recent years, countries in Asia have had the worst outdoor air pollution; Asia, Africa and SA have health issues mainly due to indoor air pollution Air pollution can happen over long distances

Sources a. natural - volcanoes - forest fires - plants b. anthropogenic - on-road vehicles (largest source of CO and NOx) - industry - power plants

Major Air Pollutants Six pollutants (criteria) – U.S. Clean Air Act a. SO2 b. NOx c. CO d. PM e. tropospheric ozone f. lead

Sulfur Dioxide (SO2) a. corrosive gas b. combustion of fossil fuels (coal and oil) c. respiratory irritant d. released from volcanoes and forest fires

1. colorless, odorless gas c. NO2 1. pungent, reddish-brown gas Nitrogen Oxides a. NOx (NO or NO2) b. NO 1. colorless, odorless gas c. NO2 1. pungent, reddish-brown gas d. nitrogen (N2) 1. makes up 78% of atmosphere Anthropogenic – motor vehicles, stationary fossil fuel combustion Natural – forest fires, lightning, bacteria in soil * Plays an important role in forming tropospheric ozone as well as photochemical smog

1. colorless, odorless gas 2. vehicle exhaust b. CO2 Carbon Oxides a. CO 1. colorless, odorless gas 2. vehicle exhaust b. CO2 2. photosynthesis/cellular respiration 3. burning of fossil fuels CO – incomplete combustion of most matter; significant in urbanized areas - dangerous indoor air pollutant if it is poorly ventilated (exhaust systems on heaters are not working properly) CO2 – complete combustion of matter and biomass

Particulate Matter (PM) a. solid or liquid particles suspended in the air b. sizes 1. ranges 0.001 micrometer to 100 micrometer 2. larger than 10 - can be filtered out by nose and throat 3. PM10 – not filtered and deposited in respiratory tract 4. PM2.5 – BIG health concern c. scatter and absorb sunlight Comes from the combustion of wood, manure and other biofuels like oil and coal and gasoline (diesel – black smoke)

Photochemical Oxidants a. sunlight acting on NOx and SO2 b. main focus – O3 (ozone) 1. most abundant in troposphere 2. respiratory inflammation 3. reacts with NOx and sulfur to form smog - photochemical * LA type, brown - sulfurous * London type, gray - atmospheric brown cloud * seen in Asia Generally harmful to plant tissue, human respiratory tissue When ozone is in the presence of nitrogen oxides and VOCs, it creates even more harmful pollutants Smog-reduced sunlight - created through the presence of sulfur and Nox and ozone and other photochemical oxidants reacting together to create certain particulate matter contributing to scattering light Atmospheric brown cloud – derived from combustion of fossil fuels and burning biomass * reduces tourism

a. occurs naturally in rocks and soil b. has been added to gasoline Lead (Pb) a. occurs naturally in rocks and soil b. has been added to gasoline c. persistent Mercury (Hg) a. coal and oil – released into atmosphere b. toxic to CNS Lead – in gasoline it improves vehicle perofrmance ; lead released into air and travels with wind and deposits by rain or snow Largest uncontrolled source of Hg – coal burning power plants

VOCs (volatile organic compounds) a. become vapors at typical atmospheric temperatures b. hydrocarbons c. gasoline, lighter-fluid, oil-based paints d. strong aromas e. lead to ozone formation

Primary and Secondary Pollutants a. direct source b. CO, CO2, SO2, NOx, most PM and VOCs Secondary a. product of primary pollutant undergoing a reaction ex) ozone (O3)

Photochemical Smog Smog a. originally – smoke, fog, and sometimes SO2 due to burning of coal b. today – brown smog still a problem c. typically urban areas, but some rural (trees and shrubs, forest fires) d. atmospheric conditions (higher temperatures) 1. emission of VOCs 2. NOx emissions from electric utilities VOCs – come from vegetation as well as gasoline especially when the temperature increases Nox – when it’s really hot outside and needing to run air conditioner * Ozone formation and photochemical oxidants occur more rapidly at higher temperatures leading to more smog formation at higher temperatures

c. no VOCs or photochemical oxidants 1 c. no VOCs or photochemical oxidants 1. ozone (O3) forms during the day and breaks down at night 2. little to no photochemical smog d. VOCs present 1. VOCs combines with NOx 2. NOx no longer available to recombine with O3 in atmosphere, therefore the O3 accumulates over time Little to no VOCs When sunlight is present – ozone forms with lots of Nox in the atmosphere At night – Nox is still present and will recombine with the ozone in the atmosphere to create O2 and NO2 The cycle of ozone formation is on a daily basis resulting in little smog Smog * Typically an urban problem but can be a problem

e. Thermal inversion 1. warm layer of air at mid-altitude covers a layer of cold, dense air below 2. warm inversion layer - traps emissions causing severe pollution - vehicle exhaust and industrial emissions Reasons for inversions when the air near the ground rapidly loses its heat on a clear night. In this situation, the ground becomes cooled quickly while the air above it retains the heat the ground was holding during the day. Topography can also play a role in creating a temperature inversion since it can sometimes cause cold air to flow from mountain peaks down into valleys. This cold air then pushes under the warmer air rising from the valley, creating the inversion. http://news.bbc.co.uk/2/hi/uk_news/magazine/7532603.stm

Acid Deposition Formation a. NOx and SOx released into atmosphere (primary)  nitric acid and sulfuric acid (secondary)  nitrate, sulfate, and hydrogen ions (generate acidity in acid deposition b. fall as wet or dry deposition c. reduced in US due to Clean Air Act

Effects a. lowers pH of water b. detrimental to aquatic organisms c. decrease in species diversity d. erode statues, monuments, and buildings e. harm tree species (Red Spruce in NE US)

Stratospheric Ozone Tropospheric Ozone Stratospheric Ozone Oxidant that harms respiratory systems Protective shield against radiation from Sun (UV-B) Air pollutant damaging lung tissue and plants Critically important to life “ground-level ozone” “global sunscreen” UV-A reaches this layer Absorbs UV-B and UV-C

Formation and Breakdown of Ozone - occurs in closed loop cycle a. O2 + UV-C  2O b. O2 + O  O3 c. O3 + UV-B or UV-C  O2 + O Ozone continuously formed/broken down in presence of sunlight UV-C breaks the bonds holding together the oxygen leaving two free oxygen molecules (only happens to a small number of oxygen molecules, therefore most of the O2 remains unaffected in the atmosphere) When the oxgen molecules (O2) reactions with the free oxygen molecules floating through the atmosphere, the result is ozone - therefore in the presence of ultraviolet radiation, oxygen is converted to ozone c. Ozone is broken down into O2 and free oxygen atoms when it absorbs with UV-C or UV-B radiation

Anthropogenic Contributions to Ozone Destruction a. Chlorine 1. major source – CFCs 2. O3 + CL  ClO + O2 ClO + O  Cl + O2 O3 + O  2 O2 3. catalyst, does not get used up 4. ozone no longer able to absorb UV-B CFCs Extremely stable Nontoxic Nonflammable Does not degrade once released into atmosphere Does not dissolve in water Does not undergo any chemical change When CFC reaches the stratosphere and is in the presence of ultraviolet radiation, the bond between the chlorine and CFC is broken, resulting in chlorine atom in the atmosphere Chlorine breaks down ozone and pulls off one free oxygen and forming a chlorine monoxide molecule and O2 Free oxygen pulls the oxygen atom from the chlorine monoxide and creating an oxygen molecule (O2) Now the free chlorine is ready to break down more ozone molecules

Depletion of Ozone layer a. greatest at the poles since 1970 b. “ozone hole” in Antarctica 1. seasonal depletion 2. cold weather - build up of ice crystals mix with NO - accumulation of Cl 3. sunny weather - UV breaks down more Cl catalyzing ozone destruction

Effort to reduce ozone depletion a. Montreal Protocol on Substances that Deplete the Ozone Layer - reduce CFC production 50% by 2000

Indoor Air Pollution Causes more deaths each year than outdoor air pollution Developing v. developed Developing Use wood, animal manure or coal for cooking Poorly ventilated Not allowed for complete combustion when burned No exhaust system CO Developed * We spend more time inside

a. insulating properties b. respiratory diseases (lung cancer) Asbestos a. insulating properties b. respiratory diseases (lung cancer) c. not dangerous until disturbed * Insulating materials become old or damaged and the fine fibers within them become airborne and get embedded into respiratory tract

Carbon Monoxide a. malfunctioning exhaust system - typically natural gas b. binds with hemoglobin more efficiently than O2 c. lead to oxygen deprivation in brain

Radon a. Radon-222, decay of uranium b. exists in bedrock c. seep through crack in foundation d. second leading cause of lung cancer

VOCs in home products a. strong aroma b. glues, paints, formaldehyde c. burning sensation of eyes, throat

Sick Building Syndrome a. high levels of VOCs and other pollutants b. headaches, sore throat, fatigue c. sources - mold, pollen - cleaning agents