Unit 7.1: Introduction to Air Pollution

• Air Pollution - anything in the atmosphere that is harmful to humans or the environment 

• Primary Pollutants are emitted directly into the atmosphere

  • Natural: pollen, volcanic ash, VOCs given off by planes

  • Anthropogenic: products of combustion of fossil fuels (CO2, NOx, SO2)

• Secondary Pollutants form once they are in the atmosphere, usually combining with water vapor or other atmospheric gasses

  • Examples: Ozone, acid rain

• Clean Air Act

  • Passed in 1963, National Ambient Air Quality Standards came in 1970

  • Has been effective in reducing criteria air pollutants

  • Six pollutants deemed most harmful to human health

    • Sulfur dioxide (SO2)

    • Particulate matter (PM)

    • Lead (Pb)

    • Ozone (O3)

    • Nitrogen dioxide (NO2)

    • Carbon monoxide (CO) 

• Lead was a gasoline additive in the 1920s

  • Low Level Lead Exposure Health Impacts

    • Children 

      • Anemia

      • Behavioral disorders

      • Lowered IQ

      • Reading and learning disabilities 

      • Nerve Damage

    • Adults

      • Hypertension 

      • Cardiovascular disease

• Combustion of Fossil Fuels Releases Carbon

  • Combustion of fossil fuels releases the energy stored during photosynthesis (remember glucose = C6H12O6)

    • All fossil fuels contain carbon and hydrogen 

    • Combustion of carbon creates carbon dioxide (CO2)

    • This carbon has not been in the atmosphere for millions of years

  • Coal contains many other elements absorbed by plants during their life or trapped in the sediments along with the organic matter 

    • These impurities are also released during combustion 

    • Specific elements vary by region

  • Combustion of coal creates pollutants of 

    • Carbon dioxide 

    • Sulfur dioxide 

    • Heavy metals

    • Particulates 

• Formation of Coal

  • Plant matter -> peat -> lignite -> bituminous -> anthracite 

• Impurities in Coal

  • Impurities in coal are released during combustion 

    • Sulfur -> sulfur dioxide (SO2)

      • Mainly present when coal is formed from marine biomes

      • Sulfur dioxide 

    • Toxic Metals

      • Lead

      • Mercury

      • Nickel

      • Arsenic

    • Partially combusted “soot”

      • Particulate matter 

        • PM carries many of the metals and heavier elements into lungs

• Sulfur in Fossil Fuels

  • Sulfur is present in larger quantities in marine fossil fuels

    • Coal burning power plants can use filters and clean coal processing to decrease sulfur dioxide emissions

    • Crude oil (petroleum) also contains sulfur

      • Diesel fuel combustion creates large amounts of sulfur dioxide

        • EPA began regulating diesel fuel sulfur levels in 1933

• Fossil Fuel Combustion Leads to Pollution 

  • The chemistry of fuels comes from the source plant matter:

    • Carbon

    • Hydrogen

    • Nitrogen 

    • Oxygen

    • Sulfur 

      • These were major biogeochemical cycles (unit 1)

  • These chemicals, when burned, create primary pollutants 

  • Anything that has negative effects on human health or the environment is considered a pol

• Effects of Fossil Fuel Pollution

  • Pollutants cause harm to human life or the environment

    • Air pollutants are likely to come in contact with eyes, nose, and throat, causing irritation

    • Inhaled pollutants exacerbate existing lung conditions and can cause permanent lung damage

    • Air pollutants can damage plant tissue during photosynthesis and respiration 

Unit 7.2: Photochemical Smog

• The combustion of fossil fuels can produce primary pollutants such as nitrogen oxide 

• Volatile Organic Hydrocarbons

  • Named “volatile” because they can vaporize at room temperature

    • Increased presence in the atmosphere 

  • Example:

    • Anthropogenic

      • Formaldehyde 

      • Gasoline

    • Natural 

      • Trees

      • Many plant oils 

• Formation of Photochemical Smog

  • Sources

    • Urban areas with many cars

  • Primary Pollutants

    • Nitrogen oxides

    • VOCs

  • Tropospheric Conditions 

    • Sunlight

    • Heat

  • Secondary Pollutants 

    • Ozone

    • PANs

      • Peroxyacyl nitrates 

• Factors Influencing Photochemical Smog

  • Timing:

    • Nitrogen oxide is produced early in the day

      • Morning rush hour

    • Ozone concentrations peak in the afternoon

      • Increase sun intensity and temperatures

  • Location and Seasonality:

    • Ozone levels are higher in sunny warm climates

    • Ozone levels are higher in the summer

• The secondary pollutants that make up what we refer to as photochemical smog

  • Ozone

  • PANs

  • Aldehydes (a category of VOCs)

  • HNO3 (nitric acid)

• Human Health Effects of Photochemical Smog

  • Photochemical Smog

    • Irritates the eyes, nose, and throat

    • Can worsen existing heart and lung conditions 

    • Regular long-term exposure can cause lung cancer

  • Tropospheric Ozone

    • Effects in humans

      • Can worsen bronchitis and emphysema 

      • Can trigger asthma 

      • Causes permanent dam age to lung tissue 

    • Additional environmental impacts of tropospheric ozone

      • Enters plants through the stomata and burns plant tissue, leading to leaf damage and reduce survival

• Reducing Photochemical Smog

  • Reduce Nitrogen Oxides:

    • Catalytic Converters

      • Convert NO into O2 and N2

      • CO and hydrocarbons react to produce CO2 and H2O 

    • Enforce emissions testing and standards for vehicles 

  • Reduce VOCs:

    • Pump gas at night 

    • Follow gasoline refueling instructions for efficient vapor recovery, being careful not to spill fuel, and always tightening your gas cap securely 

Unit 7.3: Thermal Inversion

• Thermal Inversion - under normal conditions in the troposphere, as the altitude increase, the temperature decreases

  • A reversal in this tend occurs in a layer above Earth’s surface

    • The warmer layer on top of the cooler surface air is referred to as an inversion

      • It is the opposite of the expected conditions 

  • Thermal inversion “traps” cooler, denser air 

    • Air does not rise, and pollutants do not disperse

      • Photochemical smog

      • Particulate matter

• Factors that Influence Thermal Inversion 

  • Geography can encourage inversion layers 

    • Valleys

    • Nearby mountain ranges

    • Coastal or prevailing winds

  • These conditions make it more likely that cool air can be trapped beneath a warm layer

  • Pollution is intensified by the inversion

    • Large cities 

    • High industrialization

    • Lots of vehicles 

  • These facts make a location more prone to suffering health effects from an inversion 

Unit 7.4: Atmospheric CO2 and Particulates

• Anthropogenic VS Natural Pollution Sources

  • Air pollution is any substance in the atmosphere that has harmful effects on people, ecosystems, or infrastructure and the economy 

• Natural Sources of Carbon Dioxide

  • Regular sources of CO2 emissions

    • Respiration

    • Ocean outgassing (diffusion)

    • Decomposing biomass

  • Geological processes

    • Volcanoes

  • Ecosystem Disturbances

    • Wildfires

• Is Carbon Dioxide a Pollutant?

  • Natural emissions are major contributor to atmospheric CO2 levels, but natural processes are also sinks for carbon dioxide 

  • The net effect of natural CO2 sources and sinks is minimal

    • Natural sources are primarily “fast carbon” and not fossil carbon

      • Burning fossil fuels for power, transportation, and creating petroleum products adds excess carbon dioxide to the atmosphere

    • CO2 is a greenhouse gas and necessary to support life and maintain global temperatures 

      • Excess CO2 that disrupts ecosystems, health, and the economy is a pollutant 

• Particulate Matter - is solid or liquid particles in the air that are small enough to be inhaled

  • Categorized based on particle size in microns (1 micron = 1 millimeter)

  • Particulate matter under 10 microns is inhalable 

    • PM10 - between 2.5 and 10 microns in diameter 

      • Between 0.0025 and 0.01 mm

    • Upper respiratory concern

  • PM2.5 - under 2.5 microns in diameter 

    • Lower respiratory concern

• Natural Sources of Particulate Matter

  • Pollen

  • Spores (plant, fungi)

  • Bacteria 

  • Dust

  • Dust mites

  • Airborne soil

  • Sea salt

  • Geological Processes:

    • Volcanic dust 

    • Sulfates

  • Ecosystem Disturbances:

    • Wildfires

Unit 7.5: Indoor Air Pollutants

• Sources of Indoor Air Pollution

  • Indoor air pollution can come from natural sources, human-made sources, and combustion

  • Natural Sources

    • Mold

    • Dust

    • Radon

  • Human-made sources

    • Asbestos

    • Combustion (smoke)

• Mold - can infect respiratory passageways

  • Water leaks and too much humidity can create perfect conditions for mold to grow

  • Can be found in homes and schools

• Dust - contain particulates of different sizes

• Smoke - produces particulates that irritate and damage respiratory systems

  • Sources of smoke include;

    • Candles burning

    • Use of fireplaces

    • Use of cookstoves that burn wood, charcoal, and animal dung

    • Use of unvented space heaters or kerosene heaters

    • Cigarette smoke

    • Smoke from nearby wildfires

• Radon - a gas resulting from decaying uranium 

  • Some rock and soils contain uranium 

  • As uranium decays into radon-222, the gas escapes into the atmosphere and can seek into homes and buildings buoy on these soils

    • Radon moves up through the soil and can then enter a home

  • It is a naturally occurring gas, you cannot see or smell 

  • It can dissolve in groundwater

  • Exposure to radon can cause lung cancer

    • Decays into radioactive particles

    • These particles are inhaled and deposited into the lungs

    • Cells of lung tissue becomes irritated, damaging DNA

    • This the second leading cause of lung cancer in America 

  • Building owners can test for radon to determine risk and reduce risk of exposure 

    • Selling cracks and venting can easily reduce risk

• Asbestos - was used in insulation can cause lung cancer

  • No longer used in schools and public buildings

• Products used to build and furnish homes and offices contribute to indoor air pollution 

  • Lead can be found in paints in older homes

  • VOCs can be found in furniture, paneling and carpets, cleaning supplies, fabric softener dryer sheets

  • Formaldehyde can be found in building materials like treated woods, carpets, glues, and resins

  • Insulation can contain asbestos in older homes and buildings

    • These tiny glass fibers can cause lung disease

• Combustion releases air pollutants 

  • Nitrogen oxide

  • Sulfur dioxide

  • Particulates 

  • Tobacco smoke

  • Carbon monoxide

    • Produced when fuel is burned

    • Household items produce fumes that release carbon monoxide poisoning 

      • Small engines, stoves, lanterns, grills and fireplaces, furnaces, and cars and trucks are examples of this

    • Reacts with hemoglobin in red blood cells to create a molecule that can no longer carry oxygen

    • Impairs that ability of red blood cells and cause dizziness, nausea, and suffocation 

Unit 7.6: Reduction of Air Pollutants 

• Clean Air Act - regulates the emission of air pollutants that affect human health

  • Regulation at a national level by cooperating with states and tribes

  • Reduction of automobile emissions

    • Eliminating lead in gasoline

    • Encouraging cleaner technologies in transportation 

  • Reduction of acid rain

    • Determine levels of how much pollution is permissible by industries 

    • Promoting technologies for reductions in sulfur dioxide and nitrogen oxides

  • Phased out pollutants depleting Earth’s stratospheric ozone

    • Regulations for managing tropospheric, or ground level ozone 

  • Sets air quality standards and encourages technologies to protect the health of humans and the environment 

• Alternative Fuels

  • Clean air act supports this because it reduces pollutants in emissions

    • Natural gas

    • Propane

    • Ethanol

    • Electricity

    • Biofuels 

• Conservation Actions to Reduce Emissions

  • Energy efficiency in appliances and buildings reduce fuel use and emissions

  • Water based rather than solvent based paints and cleaners reduce VOCs

  • Improved transportation planning for passengers and freight reduce fuel use and emissions 

  • Higher fuel standards and cleaner running engines for cars, trucks, and planes reduce fuel use

  • Individual and community actions like composting, recycling, carpooling, no-idle zones, and other actions can have large impacts

• Vapor recovery nozzles reduce fumes

  • The vapor recovery system captures the vapors and sends them to the underground storage tank

  • New technologies improve reductions, and more efficient nozzles have been designed 

• Catalytic converters reduce the toxicity of emissions

  • Nitrogen oxide pollution is reduced by a catalyst through a reduction reaction (removing oxygen). This breaks up nitrogen oxides into nitorgen and oxygen gases.

  • Another catalyst works by an opposite chemical reaction called oxidation (adding oxygen) and turns carbon monoxide into carbon dioxide.

    • Another oxidation reaction turns unburned hydrocarbons in the exhaust into carbon dioxide and water.

• Scrubbers remove pollutants from exhaust streams

  • When coal is burned, there are pollutants that are released as gas and particulates

  • These gasses are released via the flue, or smokestacks, and enter the atmosphere where they cause air and water pollution 

  • The Clean Air Act requires scrubber technologies to remove pollutants like sulfur oxides, nitrogen oxides, and particulates

• Wet scrubbers use liquids to capture pollutants

  • Wet scrubbers use a spray, or mist, of liquid to capture or change pollutants

  • When particulates and dust are an issue, water alone can be the liquid

  • For sulfur oxides, the liquid is often a combination of limestone powder and water that makes a slurry

  • The sulfur oxides interact with the limestone (a buffer) and converts it into a synthetic form of gypsum

  • This gypsum can be used as drywall, not all industries utilize this product

• Dry scrubbers use dry substances to capture pollutants

  • They use dry particles, or reagents, to capture or change pollutants

  • Due to added weight, the particles will then fall to the bottom of the chamber and be collected by a screen

  • Although highly effective, dry scrubbers don’t remove as many pollutants as wet scrubbers

• Electrostatic Precipitators Use Electrical Charge to Reduce Pollutants

  • These devices force the gas through a chamber that adds a charge to the pollutants

  • As the soot particles move past metal plates or filters that have an opposite charge, the particles stick there

  • These devices can be used as the first step before the flue gases move into a scrubber chamber

• Technologies are effective but create a waste product 

• Managing the waste ash and sludge can cause issues, these need to managed to prevent threats to the environment and human health

Unit 7.7: Acid Rain

• The pH scales measures acidity and alkalinity of materials 

• There are both natural and human-made sources of acid rain

• Vehicles burning fossil fuels emit nitrogen oxides (NOx)

  • Nitrogen oxide reacts with water resulting in nitrous acid with nitric acid

• Coal-burning power plants release nitrogen oxides (NOx) and sulfur dioxides (SO2)

  • Sulfur dioxide reacts with water, resulting in sulfurous acid then sulfuric acid

• Natural source emit some acid forming compounds 

  • Volcanos, geysers, and hot springs can contribute sulfur dioxides, nitrogen oxides, and carbon dioxide to the atmosphere 

    • However, most of these pollutants that cause acid rain are from the burning of fossil fuels

• Formation of Acid Rain

  • Nitric acid and sulfuric acid can be in the form of dry deposits or rain/snow

• The Acid Rain Pathway

  • Sulfur dioxide and nitrogen oxides from our burning of fossil fuels and some natural sources enter the atmosphere

  • SOx and NOx react with water in the atmosphere and are carried long distances by winds

    • These pollutants can travel long distances, as when they are released high into the atmosphere, this gives them more time to react with water, increasing the likelihood that acid rain will form

    • Acid deposition can greatly impact communities and environments downwind of coal-burning power plants

  • Acid rain and dry particles can then call to the Earth’s surface

  • Forests, soils, and aquatic systems, even human structures are impacted by acid deposition 

• Forests and Soils are Impacted Several Ways

  • Aluminum Toxicity 

    • Acid rain promotes aluminum ions to leach from soils, which is toxic to plants and aquatic life

  • Calcium Deficiencies

    • Tree roots are unable to take up calcium when aluminum ions are present

    • Calcium is critical for normal cell processes, and without it trees and plants suffer

  • Reduced Photosynthesis 

    • Damaged needles and leaves, as well as nutrient deficiencies caused by changing soil chemistry, means plants don’t photosynthesize as effectively 

• Aquatic life has a range of tolerance for acidic conditions

  • More acidic lakes and streams can result in death, skeletal deformities, and damaged eggs of fish and other aquatic life

• Acid rain damages human-made structures 

  • Metal and stone can be eroded by acid deposition

  • Many statues are made of marble a rock that contains calcite, which is dissolved by acid deposition

• Not all regions respond the same way

  • The bedrock and soils determine how vulnerable an area is to acid rain

  • Soils rich in magnesium, calcium carbonate, and limestone can buffer, or neutralize, the acid 

  • Lakes surrounded by granite that have thin, nutrient poor soils, are vulnerable

  • Forests and lakes or New England, and high elevations, have those conditions

Unit 7.8: Noise Pollution

• Noise can cause damage to human health

• Noise Pollution - any noise that causes stress or has the potential to damage human health

  • Noise is measured in decibels on a logarithmic scale

  • Human hearing can be damaged with sudden or prolonged exposure above 85 decibels 

• Sources of Noise Pollution

  • Transportation 

    • Loud noise levels are associated with railroads, mass transit, airports, sirens, heavy traffic, and even motorcycles

  • Machinery associated wit industry 

  • Construction activities 

    • Trucks jackhammers, nail guns, and other activities 

• Hearing loss is one consequence of noise pollution 

  • Other consequences include

    • Stress

    • Depression

    • Anxiety

    • High blood pressure

    • Heart disease 

• US Noise Control of 1972 - enables the Environmental Protection Agency to regulate noise. EPA sets emission standards for courses of noise from transportation, machinery, and construction 

• The Occupational Safety and Health Association (OSHA) sets limits on noise exposure in the workplace 

• The Quiet Communities Act provides funding to help communities reduce noise associated with airports

• Noise pollution can cause stress

  • Anthropogenic noise can cause stress, resulting in

    • Reduced reproduction 

    • Decline in overall health

    • Disrupted communication 

• Noise can mask sounds for both predator and prey

  • By masking sounds, noise pollution can make it difficult for

    • Predators to find prey

    • Prey to elude predators

• Noise pollution can altar migration routes

  • Birds, whales, and game animals like these mule deer are impacted by noise from machinery and transportation

  • During migration, animals avoid areas that previously provided critical food, nesting, or resting