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”

Sources a. natural - volcanoes - forest fires - plants b. anthropogenic - on-road vehicles (largest source of CO and NO x ) - industry - power plants

Major Air Pollutants Six pollutants (criteria) – U.S. Clean Air Act a. SO 2 b. NO x c. CO d. PM e. tropospheric ozone f. lead

Sulfur Dioxide (SO 2 ) a. corrosive gas b. combustion of fossil fuels (coal and oil) c. respiratory irritant d. released from volcanoes and forest fires

Nitrogen Oxides a. NO x (NO or NO 2 ) b. NO 1. colorless, odorless gas c. NO 2 1. pungent, reddish-brown gas d. nitrogen (N 2 ) 1. makes up 78% of atmosphere

Carbon Oxides a. CO 1. colorless, odorless gas 2. vehicle exhaust b. CO 2 1. colorless, odorless gas 2. photosynthesis/cellular respiration 3. burning of fossil fuels

Particulate Matter (PM) a. solid or liquid particles suspended in the air b. sizes 1. ranges micrometer to 100 micrometer 2. larger than 10 - can be filtered out by nose and throat 3. PM 10 – not filtered and deposited in respiratory tract 4. PM 2.5 – BIG health concern c. scatter and absorb sunlight

Photochemical Oxidants a. sunlight acting on NO x and SO 2 b. main focus – O 3 (ozone) 1. most abundant in troposphere 2. respiratory inflammation 3. reacts with NO x and sulfur to form smog - photochemical * LA type, brown - sulfurous * London type, gray - atmospheric brown cloud * seen in Asia

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

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 Primary a. direct source b. CO, CO 2, SO 2, NO x, most PM and VOCs Secondary a. product of primary pollutant undergoing a reaction ex) ozone (O 3 )

Photochemical Smog Smog a. originally – smoke, fog, and sometimes SO 2 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. NO x emissions from electric utilities

c. no VOCs or photochemical oxidants 1. ozone (O 3 ) forms during the day and breaks down at night 2. little to no photochemical smog d. VOCs present 1. VOCs combines with NO x 2. NO x no longer available to recombine with O 3 in atmosphere, therefore the O 3 accumulates over time

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

Acid Deposition Formation a. NO x and SO x 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 OzoneStratospheric 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 layerAbsorbs UV-B and UV-C

Formation and Breakdown of Ozone - occurs in closed loop cycle a. O 2 + UV-C  2O b. O 2 + O  O 3 c. O 3 + UV-B or UV-C  O 2 + O Ozone continuously formed/broken down in presence of sunlight

Anthropogenic Contributions to Ozone Destruction a. Chlorine 1. major source – CFCs 2. O 3 + CL  ClO + O 2 ClO + O  Cl + O 2 O 3 + O  2 O 2 3. catalyst, does not get used up 4. ozone no longer able to absorb UV-B

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

Asbestos a. insulating properties b. respiratory diseases (lung cancer) c. not dangerous until disturbed

Carbon Monoxide a. malfunctioning exhaust system - typically natural gas b. binds with hemoglobin more efficiently than O 2 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