Unit 7 - Atmospheric Pollution Flashcards
1
Q
***Write about air pollutants (specific molecules or particles) not just air “pollution” as an idea
A
2
Q
Clean Air Act
A
Clean Air Act (1970) identified 6 criteria air pollutants that EPA is required to set acceptable limits for, monitor, and enforce
- SO2, NOx, CO, PM, O3, Pb
3
Q
SO2 (sulfur dioxide)
A
- formed from Coal combustion (electricity)
- Respiratory irritant, smog, acid precipitation
4
Q
NOx (nitrogen oxides)
A
- formed from All FF combustion (gas esp.)
- O3 | photochemical smog | acid precip.
5
Q
CO
A
- formed from incomplete combustion
- O3, lethal to humans
6
Q
PM (particulate matter)
A
- FF / biomass combustion
- respiratory irritant | smog
7
Q
O3 (tropospheric ozone)
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- formed from the Photochemical oxidation of NO2
- Respiratory irritant|smog|plant damage
8
Q
Pb (lead)
A
- formed from metal plants, waste incineration
- Neurotoxicant
9
Q
Air Pollutants vs Greenhouse Gases
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- CO2 is NOT one of the 6 criteria pollutants in the Clean Air Act
- CO2 does not directly lower air quality from human standpoint (not toxic to breath, not damaging to ENT, does not lead to smog)
- CO2 is a GREENHOUSE GAS, it leads to earth warming => env. and human health consequences
10
Q
Coal Combustion
A
- releases more air pollutants than other FF’s
- 35% of global electricity
11
Q
Impacts of SO2
A
- respiratory irritant (inflammation of lungs), asthma, bronchitis
- sulfur aerosols (suspended sulfate particles) block incoming sin, reducing visibility and photosynthesis
- forms sulfurous smog
- combines w water and O2 in atmosphere to form sulfuric acid => acid rain
12
Q
EPA and Lead
A
- Before CAA, lead was a common gasoline additive; EPA began phaseout of lead from gasoline in 1974
- vehicles made post 1974 are required to have catalytic converters to reduce NOx and HC emissions (lead damages converters)
- damages nervous system
13
Q
primary air pollutants
A
- emitted directly from sources such as vehicles, power plants, factories, or natural sources (volcanoes, forest fires)
- NOx, CO, VOCs, SO2, PM, hydrocarbons
14
Q
Secondary Air Pollutants
A
- primary pollutants that have transformed in presence of sunlight, water, O2
- occur more during the day (since sunlight often drives formation)
- tropospheric O3
- sulfuric acid (H2SO4) & sulfate (SO4-2)
- nitric acid and nitrate ion
15
Q
Photochemical Smog Precursors
A
~ NO2 - broken by sunlight into NO + O (free O + O2 => O3)
~ VOCs - Volatile Organic Compounds (Hydrocarbons) that bind with NO & form photochemical oxidants
- carbon based compounds that volatize (evaporate) easily (this make them smelly)
- sources: gasoline, formaldehyde, coniferous trees, oil based paints, cleaning fluids
~ O3 - forms when NO2 is broken by sunlight and free O binds to O2
16
Q
Photochemical Smog Conditions
A
- Sunlight: drives O3 formation by breaking down NO2 => NO + O; then free O binds with O2
- Warmer: Hotter atmo. temp. speeds O3 formation, evaporation of VOCs and thus smog formation
17
Q
factors that increase smog formation
A
- more sunlight (summer, afternoon) = more O3
- higher temp speeds evap. of VOC’s & rxn that leads to O3
- high VOCs emissions (gas stations, laundromats, plastic factories)
- higher vehicle traffic, higher NO2 emissions, and therefore O3 formation
18
Q
impact of smog
A
environment - reduces sunlight; limiting photosynthesis
- O3 damages plant stomata and irritates animal resp. tracts
humans - resp. irritant; worsens asthma, bronchitis, COPD; irritates eyes
economic - high healthcare costs to treat asthma, bronchitis, COPD
- lost productivity due to sick workers missing work or dying
- ag. yields due to low sunlight reaching crops and damage to plant stomata
19
Q
reduction of smog
A
Vehicles - decreasing the # of vehicles on the road lowers NO2 emissions
- decrease vehicles = low gas = low VOCs
(carpooling, public transport, biking, walking, etc.)
Energy - increased electricity production from renewable sources that don’t emit NOx (solar, wind, hydro)
- natural gas power plants release far less NOx than coal
20
Q
urban heat island effect
A
urban areas tend to have higher surface and air temperature than surrounding suburban and rural areas due to:
- lower albedo; concrete and asphalt absorb more of sun’s energy than areas with more vegetation
- less evapotranspiration: water evaporating from surfaces and transpiration from plants carries heat from surface into atmosphere and cools off rural and suburban areas w vegetation
21
Q
normal convection
A
- normally, the atmosphere is warmest at earths surface and cools as altitude rises
- because warm air rises, air convection carries air pollutants away from earth’s surface and distributes them higher into the atmosphere
22
Q
thermal inversion
A
- because cold air at the surface is trapped beneath the warmer mass above, convection doesn’t carry pollutants up and away
- during a thermal inversion, a cooler air mass becomes trapped near earth’s surface (inverting normal gradient)
- due to a warm front moving in over it
- due to hot urban surfaces cooling overnight while IR radiation absorbed during the day is still being released
23
Q
effects of thermal inversion
A
- air pollutants (smog, PM, ozone, SO2, NOx) trapped closer to earth
- respiratory irritant
- decreased tourism revenue
- decreased photosynthetic rate
24
Q
Natural Sources of Air Pollutants
A
- Lightning Strikes (Convert N2 in atm. to NOx)
- forest fires (CO, OM, NOx)
- plants (esp. conifers) - emit VOC’s
- volcanoes - SO2, PM, CO, NOx
25
natural sources of CO2 & PM
- respiration: all living things release CO2
- aerobic decomp: decomp of organic matter by bacteria and decomposers in the presence of oxygen => releases CO2
- anaerobic decomposition: decomp of organic matter by bacteria and decomposers in low or O2 free conditions => releases CH4
- natural PM sources: sea salt, pollen, ash from forest fires, volcanic dust => leads to haze
26
Particulate Matter
solid or liquid particles suspended in air (also referred to as "particulates")
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PM10
particles or droplets like dust, pollen, ash, pr mold
- too small to be filtered out by nose hairs and trachea cilia; can irritate respiratory tract & cause inflammation
28
PM2.5
- particles from combustion (esp. vehicles) smaller dust particles
- more likely to travel deep into the lungs due to smaller size
- associated with chronic bronchitis and increased risk of lung cancer
29
Indoor Air Pollutants: developing nations
- developing nations use more subsistence fuels such as wood, manure, charcoal (biomass)
- these biomass fuels release CO, PM, NOx, VOCs
- often combusted indoors with poor ventilation, leading to high concentrations
- est. 3 billion people globally cook with subsistence fuels, resulting in est. 3.5 - 4.3 million deaths annually
30
Indoor Air Pollutants: developed nations
- developed nations use more commercial fuels (coal, oil, natural gas) supplied by utilities
- typically burned in closed, well ventilated furnaces, stoves, etc
- come from chemicals in products: adhesives in furniture, cleaning supplies, insulation, lead paint
31
INDOOR AIR: PM and Asbestos
- PM is a common indoor air pollutant
ex: smoke (from indoor biomass combustion or cigarettes), dust, and asbestos
- asbestos is a long, silicate particle previously used in insulation ( since been linked to lung cancer and asbestosis)
- phased out of use, but still remains in older building
- not dangerous until insulation is disturbed and asbestos particles enter air and then resp. tract
- should be removed by trained professionals
32
INDOOR AIR: CO
- CO is produced by incomplete combustion of basically any fuel
- CO is an asphyxiant = causes suffocation due to CO binding to hemoglobin
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how is CO released in developing nations
CO emitted from indoor biomass combustion for heating or cooking
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how is CO released in developed nations
CO released into home by malfunctioning natural gas furnace ventilation
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VOCs
- chemicals used in variety of home products that easily vaporize, enter air, and irritate eyes, lungs, bronchioles
- adhesives/sealants
- formaldehyde
- cleaners
- plastics and fabrics
36
Radon Gas
- Radon 222 is a radioactive gas released by decay of uranium naturally found in rocks underground (granite especially)
- usually enters homes through cracks in foundation
- can also seep into groundwater sources and enter body through drinkning water
- 2nd leading caused of lung cancer after smoking
- EPA recommends testing homes with airborne Radon monitor
- seal cracks in foundation to prevent entering
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reducing emission = reducing air pollutants
- drive less, walk/bike/bus more
- conserve electricity (smart appliances)
- eat more plants, less meat
- renewable, non-pollution emitting energy (solar, wind, hydro)
38
clean air act
- 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
39
pollution credits
- similar to ITQs for fish
- companies that reduce emissions well below EPA-set levels earn pollution credits
- they can sell these to companies that release more than acceptable levels
40
CAFE Vehicle Standards
- (Corporate Avg Fuel Economy) 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, CO2
41
vapor recovery nozzle
- capture hydrocarbon VOCs released from gasoline fumes during refueling
- separate tube inside nozzle captures vapors and returns the, to underground storage tank beneath the gas station
- reduces VOCs, which contribute to smog and irritate resp. tracts
- also reduces benzene (carcinogen) released from gasoline vapors
42
baghouse filter (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 and taken to landfill
43
Catalytic Converter
- required on all vehicles since 1975
- contains metals that bind to NOx and CO
- CC converts NOx, CO, and other hydrocarbons into CO2, N2, O2, & H2O
44
crushed limestone (SO2)
- used to reduce SO2 from coal power plants
- crushed coal mixed with limestone before being burned in boiler
- limestone combines with SO2 to produce calcium sulfate, reducing the SO2 being emitted
- limestone can be used to make gypsum wallboard or sheetrock for home foundations
45
fluidized bed combustion
- fluidized jets of air pumped into combustion bed
- jets of air bring more O2 into rxn, making combustion more efficient and bringing SO2 into more contact with limestone
- also allows coal to be combusted at lower temp, which emits less NOx
46
Wet and Dry Scrubbers
are air pollution control devices that remove particulates and/or gases from industrial
exhaust streams.
47
urban noise pollution
any noise at great enough volume to cause physiological stress (difficulty communicating, headaches, confusion) or hearing loss
- constructions
- transportation
- industrial activities
- domestic activity
