Atomosphere & Air Pollution& Solid Waste Miller Chapters 18 & 19 & 21 Many Slides from Mark Ewoldsen, Ph.D. La Canada HS

Take a minute to view our majestic planet

Natural sources of air pollution dust storms volcanoes fires

The atmosphere is composed of nitrogen (N2) 78%, oxygen (O2) 21%, argon (Ar) 93%, water vapor(H2O), and a number of trace gases

2 H2 + O2   -->   2 H2O Write the equations for photosynthesis and respiration

Pollutant Chemical Reaction Carbon Monoxide (CO) 2 C + O2 ------2 CO Carbon Dioxide (CO 2) C + O 2 ------ 2 CO 2 Nitric Oxide (NO) N2 + O2 -------- 2NO Nitrogen dioxide (NO2) 2NO + O2 ----------- 2NO 2 Sulfur dioxide (SO2) S + O2 ---------------- SO2

Artificial sources of air pollution Human-caused air pollution includes: Point sources = specific spots where large amounts of pollution are discharged (factory smokestacks) Non-point sources = diffuse, often made up of many small sources (charcoal fires from thousands of homes)

Artificial sources of air pollution Human-caused air pollution includes: Primary pollutants = emitted into troposphere in a directly harmful form (soot, carbon monoxide) Secondary pollutants = produced when primary pollutants and chemicals already present in the atmosphere to form new harmful chemicals (ozone in troposphere)

Criteria Air Pollutants EPA uses six "criteria pollutants" as indicators of air quality Nitrogen Dioxide: NO2 Ozone: ground level O3 Carbon monoxide: CO Lead: Pb Particulate Matter: PM10 (PM 2.5) Sulfur Dioxide: SO2 Volatile Organic Compounds: (VOCs) EPA established for each concentrations above which adverse effects on health may occur

Primary Pollutants CO CO2 Secondary Pollutants SO2 NO NO2 SO3 Most hydrocarbons HNO3 H2SO4 Most suspended particles H2O2 O3 PANs SO4 2 – Most NO3 – and salts Natural Sources Stationary Mobile

Human Impact on Atmosphere Burning Fossil Fuels Using Nitrogen fertilizers and burning fossil fuels Refining petroleum and burning fossil fuels Manufacturing Adds CO2 and O3 to troposphere Global Warming Altering Climates Produces Acid Rain Releases NO, NO2, N2O, and NH3 into troposphere Produces acid rain Releases SO2 into troposphere Releases toxic heavy metals (Pb, Cd, and As) into troposphere www.dr4.cnrs.fr/gif-2000/ air/products.html

Nitrogen Dioxide (NO2) Properties: reddish brown gas, formed as fuel burnt in car, strong oxidizing agent, forms Nitric acid in air Effects: acid rain, lung and heart problems, decreased visibility (yellow haze), suppresses plant growth Sources: fossil fuels combustion @ higher temperatures, power plants, forest fires, volcanoes, bacteria in soil Class: Nitrogen oxides (NOx) EPA Standard: 0.053 ppm

Air Pollution over China-The Asian Black Cloud

Ozone (O3) Properties: colorless, unpleasant odor, major part of photochemical smog Effects: lung irritant, damages plants, rubber, fabric, eyes, 0.1 ppm can lower PSN by 50%, Sources: Created by sunlight acting on NOx and VOC , photocopiers, cars, industry, gas vapors, chemical solvents, incomplete fuel combustion products Class: photochemical oxidants

Ozone (O3) 10,000 to 15,000 people in US admitted to hospitals each year due to ozone-related illness Children more susceptible Airways narrower More time spent outdoors

Carbon Monoxide (CO) Properties: colorless, odorless, heavier than air, 0.0036% of atmosphere Effects: binds tighter to Hb than O2, mental functions and visual acuity, even at low levels Sources: incomplete combustion of fossil fuels 60 - 95% from auto exhaust Class: carbon oxides (CO2, CO) EPA Standard: 9 ppm 5.5 billion tons enter atmosphere/year

Lead (Pb) Properties: grayish metal Effects: accumulates in tissue; affects kidneys, liver and nervous system (children most susceptible); mental retardation; possible carcinogen; 20% of inner city kids have [high] Sources: particulates, smelters, batteries Class: toxic or heavy metals EPA Standard: 1.5 ug/m3 2 million tons enter atmosphere/year

Suspended Particulate Matter (PM10) Properties: particles suspended in air (<10 um) Effects: lung damage, mutagenic, carcinogenic, teratogenic Sources: burning coal or diesel, volcanoes, factories, unpaved roads, plowing, lint, pollen, spores, burning fields Class: SPM: dust, soot, asbestos, lead, PCBs, dioxins, pesticides EPA Standard: 50 ug/m3 (annual mean)

Sulfur Dioxide (SO2) Properties: colorless gas with irritating odor Effects: produces acid rain (H2SO4), breathing difficulties, eutrophication due to sulfate formation, lichen and moss are indicators Sources: burning high sulfur coal or oil, smelting or metals, paper manufacture Class: sulfur oxides EPA Standard: 0.3 ppm (annual mean) Combines with water and NH4 to increase soil fertility

VOCs (Volatile Organic Compounds) Properties: organic compounds (hydrocarbons) that evaporate easily, usually aromatic Effects: eye and respiratory irritants; carcinogenic; liver, CNS, or kidney damage; damages plants; lowered visibility due to brown haze; global warming Sources: vehicles (largest source), evaporation of solvents or fossil fuels, aerosols, paint thinners, dry cleaning Class: HAPs (Hazardous Air Pollutants) Methane Benzene Chlorofluorocarbons (CFCs), etc. Concentrations indoors up to 1000x outdoors 600 million tons of CFCs

Other Air Pollutants Carbon dioxide ChloroFluoroCarbons Formaldehyde Benzene Asbestos Manganese Dioxins Cadmium Others not yet fully characterized

Formation & Intensity Factors Local climate (inversions, air pressure, temperature, humidity) Topography (hills and mountains) Population density Amount of industry Fuels used by population and industry for heating, manufacturing, transportation, power Weather: rain, snow,wind Buildings (slow wind speed) Mass transit used Economics

Smog Forms ...when polluted air is stagnant (weather conditions, geographic location) Los Angeles, CA

Primary Pollutants CO CO2 Secondary Pollutants SO2 NO NO2 SO3 Most hydrocarbons HNO3 H2SO4 Most suspended particles H2O2 O3 PANs SO4 2 – Most NO3 – and salts Natural Sources Stationary Mobile

Photochemical Smog UV radiation H2O + O2 Primary Pollutants NO2 + Hydrocarbons Secondary Pollutants HNO3 O3 nitric acid ozone Photochemical Smog Auto Emissions

Air Pollution Results

Six “criteria pollutants” Emissions of all of these, especially lead and carbon monoxide, have substantially declined since 1970.

Volatile organic compounds “VOCs” are regulated by many governments. Large group of potentially harmful carbon- containing chemicals used in industrial processes. Hydrocarbons are one example. About half are human-made, half natural. VOCs contribute to smog, produce secondary pollutants.

Toxic air pollutants Toxic air pollutants = chemicals known to cause serious health or environmental problems Include substances known to cause cancer and reproductive defects, and substantial ecological harm Most produced by human activities 188 toxic air pollutants are regulated under the 1990 Clean Air Act.

Industrial smog Smog from industrial pollution, fossil-fuel combustion The kind that blanketed London in 1952 “Gray air smog” Contains soot, sulfur, CO, CO2…

Industrial smog The U.S. had its own “killer smog” from industrial pollution. Shown is Donora, Pennsylvania, in 1948, at mid-day. Subsequent demand for legislation against pollution made U.S. air much cleaner.

Industrial smog Chemistry of industrial smog: • Burning sulfur-rich oil or coal creates SO2, SO3, sulfuric acid, ammonium sulfate. • Carbon leads to CO2 and CO.

The star pollutants mentioned are sulfur dioxide, nitrogen dioxide and particulates caused by an assortment of methods such as burning fossil fuels, bi products of power plants or even particles that include lead, dust ammonia and other harmful substances

Photochemical smog Smog from reaction of sunlight with pollutants The kind that blankets so many American cities today “Brown air smog” Contains tropospheric ozone, NO2, VOCs, 100 more… Hot sunny days in urban areas create perfect conditions.

Photochemical smog Mexico City and many of the world’s cities suffer from the brownish haze of photochemical smog. Inversion layers and mountains can trap smog over certain cities.

Photochemical smog Chemistry of photochemical smog: Nitric oxide starts a chain reaction. Reaction with sunlight, water vapor, hydrocarbon, results in over 100 secondary pollutants.

Stratospheric ozone depletion NASA Video on Ozone Hole Ozone at low altitudes = beneficial layer protecting us from UV radiation Ozone layer— ~ 12 parts per million in lower stratosphere—is enough to absorb UV and protect us. But in the 1960s scientists noticed ozone concentrations were dropping.

Stratospheric ozone depletion In 1974, Sherwood Rowland and Mario Molina pegged the blame on chlorofluorocarbons (CFCs). They won the Nobel Prize for this scientific detective work. CFCs = human-made molecules in which hydrogens of hydrocarbons are replaced by chlorine and fluorine atoms Mass-produced by industry, in refrigerants and consumer products like aerosol sprays

Stratospheric ozone depletion CFCs persist in the stratosphere. They split oxygen atoms off ozone (O3) to form oxygen (O2). 1 Cl atom can split many O3 molecules

Stratospheric ozone depletion In 1985, the “ozone hole” was detected over Antarctica. Ozone levels had declined 40–60% over the previous decade.

Stratospheric ozone depletion Scientists worried about the effects of extra cancer-causing UV on people, organisms, ecosystems. The ozone hole (blue) reached its greatest extent in September 2000 (satellite imagery).

Stratospheric ozone depletion The Dobson spectrophotometer, invented in 1924, can infer ozone concentrations from the ground, and helped scientists detect ozone depletion.

Stratospheric ozone depletion In 1987, over 180 nations signed the Montreal Protocol, which restricted CFC production globally. Follow-up agreements strengthened the pact. Today CFC levels are down, and stratospheric ozone is starting to recover. The Montreal Protocol is one of the biggest environmental success stories of our time. We have apparently avoided a major environmental problem.

Stratospheric ozone depletion Reasons for success of the Montreal Protocol: • Government and industry cooperated on finding solutions (cheap replacement technologies for CFCs), so battles typical to environmental debates were minimized. • Protocol was implemented with “adaptive management”—ability to fine-tune actions as time goes on, in response to new data or conditions.

Clean Air Act legislation Major air pollution legislation: Clean Air Act of 1970: Set stricter standards than previous laws Imposed emissions limits Provided research funds Enabled citizens to sue violating parties Clean Air Act of 1990: Strengthened previous regulations Introduced emissions trading for sulfur dioxide