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APES Unit 7
| Question | Answer |
|---|---|
| The 6 Criteria Air Pollutants that the EPA sets acceptable limits for, monitor, and enforce | Sulfur dioxide (SO2), Nitrogen Oxides (NO & NO2), Carbon Monoxide (CO), Particulate Matter (PM), Ozone (O3) (tropospheric), Lead (Pb) |
| What act requires that EPA to set acceptable limits for, monitor, and enforce for 6 air pollutants? | Clean Air Act (1970) |
| What ruling found that EPA could regulate greenhouse gases | 07’ SC ruling , and it began doing so in 09’ |
| Does CO2 directly lower air quality from a human health standpoint. Why not? | No Not toxic to organisms to breath Not damaging to lungs/eyes Does not lead to smog, decreased visibility Does not destroy the ozone layer |
| Why is CO2 allowed to be monitored? | is a greenhouse gas; it does lead to earth warming, and thus env. and human health consequences |
| What does coal combustion release? | CO, CO2, SO2, NOx toxic metals (mercury, arsenic, lead), and PM (often carries the toxic metals) |
| Impacts of SO2 | Respiratory irritant, worsens asthma & bronchitis Sulfur aerosols (suspended sulfate particles) block incoming sun, reducing visibility & photosynthesis sulfurous (grey) smog Combines with water & O2 in atmo., forms sulfuric acid → acid precip. |
| How is NOx released? | Released by combustion of anything, especially FFs & biomass |
| How does NO form? How does it become NO2? | - when N2 combines with O2 (esp. during combustion) - can become NO2 by reacting with O3 or O2 |
| What converts NO2 back into NO | Sunlight |
| Env. & Human Health Impacts of NOx | Resp. irritant Leads to tropospheric ozone (O3) formation, which leads to photochemical smog Combines with water & O2 in atm. to form nitric acid → acid precipitation |
| What was lead commonly in before the CAA and what was changed | gasoline Changed: 1974 EPA began phaseout of lead from gasoline in 1974 vehicles made after 1974 were required have catalytic converts to reduce NOX, CO, and hydrocarbon emissions (lead damages catalytic converters) |
| What type of toxin is lead | neurotoxicant (damages nervous systems of humans |
| What are primary air pollutants | Emitted directly from sources such as vehicles, power plants, factories, or natural sources (volcanoes, forest fires) |
| Examples of primary air pollutants | NOx, CO, CO2*, VOCs, SO2, PM, hydrocarbons |
| What are secondary air pollutants | Primary pollutants that have transformed in presence of sunlight, water, O2 (Occur more during the day, since sunlight often drives formation) |
| Examples of secondary air pollutants | Tropospheric O3 (Ozone) Sulfuric acid (H2SO4) & sulfate (SO42-) Nitric acid (HNO3) & nitrate (NO3-) |
| How is SO2 released? | Coal combustion (electricity) |
| How is CO released and what are it's consequences ? | Incomplete combustion O3 | Lethal to humans |
| How is PM released and what are it's consequences? | FF/biomass combustion Consequences: Resp. irr. | smog |
| How is O3 released and what are it's consequences? | Photochemical oxidation of NO2 Consequences Resp. irr | smog | plant/stomata damage, limits growth |
| How is Lead released and what are it's consequences? | Metal plants, waste incineration Consequences: Neurotoxicant |
| Precursors of Smog | NO2, VOCS, O3 |
| What are VOCS | Volatile organic compounds (hydrocarbons) that bind with NO & form photochemical oxidants Carbon-based compounds that volatilize (evaporate) easily (this makes them “smelly”) |
| Sources of VOCS | gasoline, formaldehyde, cleaning fluids, oil-based paints, even coniferous trees (pine smell) |
| How is NO2 a precursor of smog | Broken by sunlight into NO + O (free O + O2 → O3) |
| How is O3 formed? | Forms when NO2 is broken by sunlight & free O binds to O2 |
| What conditions lead to smog and how? | Sunlight: Drives O3 formation by breaking down NO2 → NO + O; then free O atom binds with O2 Warmth: Hotter atm. temp. speeds O3 formation, evaporation of VOCs & thus smog formation |
| Steps of Normal O3 formation | 1. Morning commute leads to high NO2 levels from car exhaust 2. Sunlight breaks NO2 into NO + O 3. O bonds with O2 to form O3 4. At night, O3 reacts with NO to form NO2 and O2 once again; O3 levels drop overnight |
| When is the peak time for O3 formation | typically peaks in afternoon when sunlight is most direct and NO2 emissions from morning traffic have peaked |
| How is photochemical smog formed? | 1. Sunlight breaks NO2 into NO + O 2. O bonds with O2 to form O3 3. VOCs bond with NO to form photochemical oxidants 4. Without NO to react with, O3 builds up & stays 5. O3 combines with photochem. oxidants (NO + VOCS) to form photochemical smog |
| Factors that increase smog formation | - Higher VOCs emissions (gas stations, laundromats, petrochem., plastic factories) - Increased vehicle traffic - More sunlight (summer, afternoon) = more O3 - Warmer temperature, speedes evap. of VOCs and rxn that lead to O3 - Urban areas |
| Why do urban areas have more smog | More traffic → more NO2 Hotter temps due to low albedo of blacktop More VOCs due to gas stations & factories More electricity demand; more NOx emissions from nearby power plants |
| Environmental impacts of Smog | Reduces sunlight; limiting photosynthesis O3 damages plant stomata and irritates animal resp. tracts |
| Human impacts of Smog | Resp. irritant; worsens asthma, bronchitis, COPD; irritates eyes |
| Economic impacts of Smog | - Increased health care costs to treat asthma, bronchitis, COPD - Lost productivity due to sick workers missing work or dying - Decreased ag. yields due to less sunlight reaching crops & damage to plant stomata |
| How to reduce smog? | Vehicles less vehicles on road= less NO2 emissions less vehicles = less gas = less VOCs Carpooling, public transit Energy Increased elect. production from renewable sources that don’t emit NOx (solar, wind, hydro) Nat. gas = far less NOx than coal |
| What Is the Urban Heat Island effect? | Urban areas tend to have higher surface & air temperature than surrounding suburban and rural areas |
| Why is there an Urban Heat Island effect? | - Lower albedo; concrete & asphalt absorb more of sun’s energy - Less evapotranspiration; water evaporating from surfaces and transpiration from plants carry heat from surface into the atmo. cools off rural & suburban areas which have more vegetation |
| Normal Atmospheric temperature gradient layers | Warm air closet to Earth's surface, cooler air, cold air |
| What happens to the Air pollutants during a normal atmospheric gradient? | Warm air rises which helps disperse pollutants like smog and PM higher into the upper atmosphere |
| What happens during a thermal inversion and what does the temperature gradient look like | During a thermal inversion, a cooler air mass becomes trapped beneath a warmer inversion layer Looks like: cooler air, warm air, cold air |
| How can thermal inversions happen? | Cold air being blown beneath warmer air above (especially in coastal cities with an ocean breeze) Urban surfaces quickly cooling off at night |
| Where do air pollutants go during a thermal inversion? | This prevents vertical mixing of air and traps pollutants like smog and PM near surface Smog, Ozone, SO2, NOx, PM are trapped closer to Earth's surface |
| Is cold air more dense or less dense than warm air? | Cold Air: More dense Warm Air: Less dense |
| Effects/Impacts of Thermal Inversions | Respiratory irritation: asthma flare ups leading to hospitalization, worsened COPD, emphysema Decreased tourism revenue Decreased photosynthetic rate |
| Natural Sources of air pollutants | Lightning Strikes (N2 gas is converted into NOx), Plants (esp. conifers) emit VOCs, Forest Fires (CO, PM, NOx), Volacnoes (SO2, PM, CO, NOx) |
| Natural Sources of CO2 | Respiration (releases Co2), Aerobic Decomposition (decay of organic matter in the presence of O2 releases CO2), anaerobic releases CH4 |
| Natural PM Sources | Sea salt, pollen, ash from forest fires & volcanoes dust (windborne soil) |
| What does PM lead to? | Leads to haze (scattering of sunlight & reduced visibility) |
| What is PM? | solid or liquid particles suspended in air (also referred to as “particulates) |
| What does PM10 mean, examples of PM10 , and consequences? | - less than 10 micrometers -Examples: dust, pollen, ash, or mold Too small to be filtered out by nose hairs and trachea cilia; can irritate respiratory tract & cause inflammation |
| What does PM2.5 mean, examples of PM2.5, and consequences? | less than 2.5 micrometers Particles from combustion (especially vehicles) smaller dust particles Ex: organic compounds, metals, Travel deep into the lungs due to smaller size Associated with chronic bronchitis + increased risk of lung cancer |
| What do developing countries use to cook, for electricity, etc and what is the consequence of this? | Subsistence fuels such as wood, manure, charcoal (biomass) - release CO, PM, NOx, VOCs ( can also cause deforestation) -Often combusted indoors with poor ventilation, leading to high concentrations |
| What type of fuels do developed nations use? | Commercial fuels (coal, oil, natural gas) supplied by utilities T(ypically burned in closed, well ventilated furnaces, stoves, etc.) |
| Where do indoor air pollutants in developed nations come from? | chemicals in products: adhesives in furniture, cleaning supplies, insulation, lead paint |
| What are common indoor air polluatants? | Radon, mold, dust, PM (dust, asbestos), VOCS, CO, Lead |
| What are examples of indoor PM? | Smoke (from indoor biomass combustion or cigarettes), dust, and asbestos |
| What is asbestos, and how can it be dangerous? | A long, silicate particle previously used in insulation , linked to lung cancer, still remains in older buildings Not dangerous until insulation is disturbed and asbestos particles enter air & then resp. tract |
| how can asbestos be removed? | Trained professionals with proper respiratory equipment, ventilation in the area it’s being removed from, plastic to seal off area from rest of the building |
| How is CO produced? | incomplete combustion of basically any fuel Not all the fuel is combusted due to low O2 or temp. (hydrocarbon and not enough O2 is burned to produced CO. |
| What is CO considered and what does that mean? | asphyxiant: causes suffocation due to CO binding to hemoglobin in blood, displacing O2 & CO2 Lethal to humans in high concentrations, esp. wuth poor ventilation |
| How is CO released in developed vs developing nations | Developed nations: CO released into home by malfunctioning natural gas furnace ventilation Developing nations: CO emitted from indoor biomass combustion for heating/cooking |
| Solution to CO | carbon monoxide detectors |
| What are VOCS and exmaples of where they can be found indoors | carbon-based chemicals used in variety of home products that easily vaporize, enter air, and irritate eyes, lungs, bronchioles Adhesives/sealants Cleaners: febreeze Plastic + Fabric: release VOCs themselves, or adhesives used in production |
| What is radon gas | Radioactive gas released by decay of uranium naturally found in rocks underground (granite especially) |
| How can radon enter human bodies | - Usually enters homes through cracks in the foundation & then disperses up from basement/foundation through home - Can also seep into groundwater sources & enter body through drinking water |
| Ways to prevent/limit radon gas | - airborne Radon monitor - Sealing cracks in foundation can prevent it from entering - increasing ventilation in the home can disperse it if it’s detected |
| How is mold developed? | Develops in areas that are dark and damp and aren’t well ventilated (under sinks/showers, behind panels in walls and ceiling) |
| What is black mold | class of mold that releases spores into air Especially harmful to resp. system |
| How does dust develop/enter human bodies? | Dust settles in homes naturally, is disturbed by movement, entering air and then respiratory tract |
| Effects of mold and dust | worsened asthma, bronchitis, COPD, emphysema |
| How to remove/prevent mold? | Can be removed by physically cleaning mold out and fixing the water leak or ventilation issue that lead to mold forming |
| Where was lead found indoors? | In homes as paint on walls, until lead paint was banned in 1978 |
| How can lead enter human bodies | The Paint chips off walls/windows and is eaten by small children (due to curiosity & sweet taste) or inhaled as dust Lead water pipes can also release lead into drinking water sources (as in Flint), less common than lead paint |
| What are the effects of lead? | Neurotoxicant, Damages central nervous system of children due to smaller size and still developing brain |
| How do prevent use of lead? | Can be removed from home by stripping lead paint and replacing with non-lead based paint Lead water pipes can be replaced by cities with copper pipes |
| Key to reduicing air polluatants + exmaples of how to | Reducing emissions = less air pollutants Ex: Drive less, walk/bike/bus more Conserve electricity (smart appliances) Eat more plants, less meat (requires less total energy to produce) Renewable, non-pollution emitting energy (solar, wind, hydro) |
| Laws /legislation that help reduce air pollutants | Clean Air Act, CAFE vehicle standards, Pollution credits |
| What does the Clean Air Act allow the EPA to do | Allows EPA to set acceptable levels for criteria air pollutants Monitor emissions levels from power plants and other facilities Tax/sue/fine corporations that release emissions above levels |
| WHat are CAFE standards | standards require the entire US “fleet” of vehicles to meet certain average fuel - Requires vehicle manufacturers to work to make more efficient vehicles More efficient vehicles burn less gasoline and release less NOx, PM, CO, and CO2 |
| What are pollution credits? | Companies that reduce emissions well below EPA-set levels earn pollution credits They can sell these to companies that release more than acceptable levels |
| Ways to Reduce Vehicle Air Pollutants | Vapor Recovery Nozzle, Catalytic Converter (CC) |
| What does a vapor Recovery nozzle do and what are the benefits of it? | Caps. hydrocarbon VOCs released from gas fumes during refueling, a tube inside nozzle caps. vapors & returns them to underground storage tank beneath gas station Reduce VOCs, (contribute to smog & irritate resp. tracts) Reduces benzene (carcinogen) |
| What is a catalytic converter (CC) | Contains metals (platinum & palladium) that bind to NOx and CO - CC converts NOx, CO, and other hydrocarbons into CO2, N2, O2, and H2O - required in vehicles after 1975 Benefits: Less NOx, CO, and other hydrocarbons emitted |
| What are ways to reduce SOx and NOx | Crushed limestone,Fluidized Bed Combustion, Dry scrubbers, wet scrubbers |
| How does crushed limestone reduce SO2 | Crushed coal mixed with limestone (calcium carbonate) before being burned Calcium carbonatecombines with SO2 to produce calcium sulfate, so less SO2 is emitted |
| What can the calcium carbonate from crushed limestone be used for | Calcium sulfate can be used to make gypsum wallboard or sheetrock for home foundations |
| How do Fluidized Bed Combustion work and reduce NOx | Fluidizing jets of air pumped into combustion “bed” Jets of air bring O2 into rxn, making combustion more efficient and bring SO2 into more contact with calcium carbonate in limestone - allows coal to be combusted at lower temp, which emits less NOx |
| How to dry scrubbers work to reduce NOx, SOx, VOCS | Large column/tube/pipe filled with chemicals that absorb or neutralize oxides (NOx, SOx, VOCs) from exhaust streams (emissions) Ex: Calcium oxide is a common dry scrubber additive which reacts with SO2 to form calcium sulfite |
| How are wet scrubbers different than dry scrubbers | - Also reduce PM - Also has a mist nozzles that trap PM in water droplets as well |
| How do dry scrubbers work to reduce NOx, SOx, VOCS, PM | May have chemical agents that absorb or neutralize pollutants but have mist nozzles that trap PM in water droplets Mist droplets w/ pollutants + PM in them go to bottom of scrubber or get trapped @ top by mist eliminator |
| Where does the polluted water go in a dry scrubbers system | Sludge collection system traps polluted water for disposal |
| How does an electrostatic precipitator work to limit PM | power plant emissions pass through device with a neg charged electrode, giving particles a neg. Charge Neg charged partic. stick to pos charged collection plates, trapping them Plates discharge= partic. fall in collection hopper 4 disposal in landfill |
| How does a baghouse filter limit PM | Large fabric bag filters that trap PM as air from combustion/industrial process passes through Shaker device knocks trapped particles loose into collection hopper below - PM collected & taken to landfill |
| WHat are the primary pollutants that cause acid depsoition | NOx and SO2 |
| Major sources of SO2 | Coal fired power plants, metal factories, vehicles that burn diesel fuel |
| Major sources of NOx | vehicle emissions***, diesel generators, coal power plants |
| How to limit acid rain | Reducing NOx & SO2 emissions reduces acid deposition Higher CAFE Standards, public transit, More efficient electricity use, Renewable energy sources, Fluidized bed combustion & lower burning temp. for existing coal power plants, Dry or wet scrubbers |
| Acid rain formation steps | 1. NOx and SO2 react with O2 and H2O in the atmosphere, forming nitric and sulfuric acid 2. Sulfuric acid and nitric acid dissociate in the presence of water into sulfate and nitrate ions, and hydrogen ions (H+) 3. more hydrogen ion = acidic rain |
| True or False: Acidic rain has a higher H+ (Hyrodgen Ion) concentration | True |
| Environmental effects of acid rain | H+ ions leech other pos. charged nutrients (Ca2+, K+) from soil H+ ions make toxic metals ( aluminum, mercury) more soluble in soil/ water = slow growth + kill animals/plants decease soil + water pH, limit tree growth in forests |
| What happens when pH leaves range of tolerance? | pop they cannot survive at all, due to: Aluminum toxicity Disrupted blood osmolarity (Na+/Cl- balance disrupted at low pH) |
| What are indicator species | species that are surveyed and used to determine conditions of an ecosystem (soil, water, etc.) |
| What can mitigate or make acid rain less severe | Adding Limestone - Calcium carbonate reacts with H+ ions, forming HCO3 and giving off Ca2+ (neutralizes acid water/soil, moves closer to 7 pH) Regions with limestone bedrock have natural buffering of acid rain - Adding crushed limestone to soil + water |
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