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clean air act (1970)
identified 6 criteria air pollutants that the EPA is required to set acceptable limits for, monitor, and enforce
6 criteria air pollutants in the clean air act
SO2
NOx
CO
PM
O3
Pb
SO2 source
coal combustion (electricity), vehicles that burn disease fuel
NOx source
All FF combustion (gas especially), vehicles emissions
negative effects of NOx
respiratory irritant
leads to smog
combines with H2O & O2 = acid rain
CO source
incomplete combustion, O3
PM Source
FF/biomass combustion, respiratory irritant, smog
O3 source
photochemical oxidation of NO2, respiratory irritant, smog, plant damage
Pb source
metal plants, waste incineration, neurotoxicant
Is CO2 an air pollutant or GHG?
GHG
does not directly lower air quality from a human health standpoint
coal combustion
releases more air pollutants than other FFs ~ 35% of global electricity
releases CO, CO2. SO2, NOx, PM, toxic metals (mercury, arsenic, lead)
negative impacts of coal combustion
respiratory irritant
sulfur aerosols block incoming sun
combines with water and O2 = acid precipitation (rain)
impacts of SOx
respiratory irritant (inflammation of bronchioles, lungs), worsens asthma & bronchitis
sulfur aerosols (suspended sulfate particles) block incoming sun, reducing visibility and photosynthesis
forms sulfurous (grey) smog
combines with water & O2 in atmosphere to form sulfuric acid → acid precipitation
NOx → NO & NO2
released by combustion of anything, especially FFs and biomass
NO forms when N2 combines with O2 (esp. during combustion)
NO can become NO2 by reacting with O3 or O2
sunlight converts NO2 back into NO
NOx impacts
respiratory irritant
leads to tropospheric ozone (O3) formation, which leads to photochemical smog
combines with water & O2 in atm. to form nitric acid → acid precipitation
VOC’s source/def.
chemicals used in variety of home products
VOC’s impacts
irritate eyes, lungs
respiratory diseases
VOC: Cleaners
Common household cleaners and deodorizers such as Febreze
VOC: Plastics and fabrics
both can release VOCs themselves, or from adhesives used in production
VOC: Adhesives/sealants
chemicals used to glue carpet down, hold furniture together, seal panels
Formaldehyde is a common adhesive in particle board and carpet glues (new carpet smell)
EPA and lead
before CAA, lead was a common gasoline additive; EPA began phaseout of lead from gasoline in 1974\
Vehicles made after 1974 are required to have catalytic converters to reduce NOx, CO, and hydrocarbons emissions (lead damages catalytic converters_
also known as neurotoxicant (damages NS of humans)
primary air pollutant
Emitted directly from sources such as vehicles, power plants, factories, or natural sources (volcanoes, forest fires)
NOx, CO, CO2*, VOCs, SO2, PM, hydrocarbons
secondary air pollutant
Primary pollutants that have transformed in presence of sunlight, water, O2
Occur more during the day (since sunlight often drives formation)
Tropospheric O3 (Ozone)
Sulfuric acid (H2SO4) & sulfate (SO42-)
Nitric acid (HNO3) & nitrate (NO3-)
impacts of PM
impact of CO
lethal to humans
impact of O3
SOx
sulfur dioxide
NOx
nitrogen oxides
CO
carbon monoxide
PM
particulate matter
VOC’s
volatile organic compounds
CO2
carbon dioxide
Pb
lead
Hg
mercury
what are vehicles made after 1974 required to have and why?
catalytic converters
photochemical smog precursors
broken by sunlight in NO
VOC’s + NO = photochemical oxidants
forms when NO2 is broken by sunlight and free O binds to O2 = O3 (ozone)
photochemical smog conditions
sunlight
warmth = hotter atmosphere speeds up O3 formation, evaporation of VOC’s → smog formation
high traffic (afternoon)
why do urban areas have more smog?
more traffic
hotter temp. due to low albedo
more VOC’s due to gas stations and factories
more electricity demand = more NO2 emissions from nearby powerplants
how does smog impact the environment?
reduces sunlight = limits photosynthesis
O2 damages plant stomata and irritates animal resp. tracts
how does smog impact humans?
resp. irritant = worsens asthma, bronchitis, COPD, irritates eyes
how does smog impact the economy?
increased health care costs
lost productivity due to sickness
decreased agriculture yields
how to reduce smog caused by vehicles?
decrease # of vehicles on the road
fewer vehicles = less gas = fewer VOCs
carpooling, biking, public transport., walking
how to reduce smog caused by energy use?
increased electricity production from renewable sources that don't emit NO2
Nat. Gas power plants release for less NO than coal
urban heat island effect
urban = higher surface and air temp
lower albedo (concrete and asphalt absorb suns energy than areas with more vegetation)
less Evo transpiration
thermal inversion
cooler air mass is trapped under a warm front near earth’s surface
what happens to air pollutants in thermal inversion?
cold air is trapped beneath the warmer mass = convection doesn’t carry pollutants up and away
warm air rises = convection carries air pollutants away from earths surface and distributes them higher into the atmosphere
effects of thermal inversion
air pollutants trapped closer to earth
respiratory irritation
decreased tourism revenue
decreased photosynthetic rate
natural sources of air pollutants
lightning strikes
forest fires
volcanoes
plants
natural sources of CO2 and PM
respiration
natural PM sources
aerobic decomposition
anaerobic decomposition
PM10
Particles or droplets like dust, pollen, ash, or mold
PM2.5
Particles from combustion (especially vehicles) smaller dust particle
developing countries
subsistence fuels ( wood, manure, charcoal)
biomass release CO, PM, NO, VOCs
combusted indoors with high concentration = high concentrations
developed nations
commercial fuels (coal, oil, natural gas)
burned in closed, well-ventilated furnaces
asbestos
long silicone particle used in insolation
radon gas
radioactive gas released by decay of uranium naturally found in rocks underground (granite especially)
how does radon gas enter homes?
through cracks in the foundation, disperses up from basement through home
seep into groundwater and enter through drinking water
what is the 2nd leading cause of lung cancer after smoking?
radon gas
how to monitor/ protect against radon gas?
testing homes with airborne Radon monitor
sealing cracks in foundation
how does dust enter air?
settles in homes -> disturbed by movement -> enters air
How does a mold form?
formed in areas that are dark and damp and not well ventilation
black mold
class of mold that releases spores into air
how to prevent mold?
removal by cleaning mold out, fixing water leaks/ ventilation issues
where is lead found in homes?
paint in old homes
how does lead come in contact with the human body?
paint chips off the walls/ windows and is eaten or inhaled as dust
found in water sources from the lead pipes
what does lead do to the human body?
damages central nervous system of children due to their small size and still developing brain
how can lead be removed
stripping lead paint
replacing lead pipes with copper pipes
how to reduce emissions?
drive less, walk/bike/bus more
conserve electricity
eat more plants, less meat
renewable, non-pollution emitting energy
pollution credits
companies that keep their levels below EPA's set levels earn pollution points
CAFE
CAFE = corporate average fuel economy
require U.S. fleet of vehicles to meet certain average fuel
requires vehicle manufacturers to make more efficient vehicles
more efficient vehicles burn less gasoline and release less NO4, PM, CO, and CO2
Vapor recovery nozzle
capture hydrocarbon VOCs released from gas fumes during refueling
how do vapor recovery nozzles reduce vehicle air pollutants?
Reduces VOCs, which contribute to smog & irritate resp. tracts
Also reduces benzene (carcinogen) released from gasoline vapors
Catalytic converter
converts harmful gases into less harmful gases and water
crushed limestone
used to reduce SO2 from coal power plants
calcium sulfate
CaSO4
calcium carbonate
CaCO3
how does crushed limestone work?
Crushed coal mixed with limestone (calcium carbonate) before being burned in boiler
Calcium carbonate in limestone combines with SO2 to produce calcium sulfate, reducing the SO2 being emitted
fluidized bed combustion
reduces SO and NO
dry scrubbers
Large column/tube/pipe filled with chemicals that absorb or neutralize oxides (NOx, SOx, VOCs) from exhaust streams (emissions)
wet scrubbers
May involve chemical agents that absorb or neutralize NOx, SOx, VOCs, but also include mist nozzles that trap PM in water droplets as well
Mist droplets with pollutants and PM trapped in them fall to bottom of scrubber or get trapped @ top by mist eliminator Sludge collection system traps polluted water for disposal
Electrostatic Precipitator
Power plant/factory emissions passed through device with a neg. charged electrode, giving particles a neg. Charge
Neg. charged particles stick to pos. charged collection plates, trapping them
Plates discharged occasionally so particles fall down into collection hopper for disposal in landfills
what does the electrostatic preceptor reduce?
PM
what does the baghouse filter reduce?
PM
baghouse filter
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
how to limit acid rain
reduce SO and NO emissions
higher CAFE standards
more public transport
renewable energy sources
more efficient electricity use
what has decreased the acid deposition?
clean air act
what happens with NO and SO2 in the atmosphere?
react with O2 and H2O and forms sulfuric acid
sulfuric acid
SO2 + O2 + H2O → H2SO4
what dissociates in the presence of water and what does it create?
sulfuric acid and nitric acid and create sulfate and nitrate ions and hydrogen ions
nitric acid
NO2 + H2O → HNO3
what does acidic rainwater decrease?
soil and water pH, limits tree growth in forests down wind
environmental effects of acid rain
soil and water acidification
as pH decreases pop declines
indicator species
if they die, something is wrong
(pH levels are too acidic)
Mitigating acid rain
limestone is a natural base that can neutralize acidic water/ soil
limiting SO2 and NO
urban noise pollution
Any noise at great enough volume to cause physiological stress (difficulty communicating, headaches, confusion) or hearing loss
examples of urban noise pollution
construction, transportation, industrial activity, domestic activity
effects of urban noise pollution on wildlife on land
can disrupt animal communication, migration, damage hearing
physiological stress = caterpillar hearts beat faster when exposed to simulated highway noise pollution
hearing = prevent predators from hearing their prey, mates from finding each other, prey hearing their predators
effects of urban noise pollution on aquatic wildlife
physiological stress = hearing loss, disrupted communication, mating calls, predator and prey navigation
seismic surveying = ships send huge air blasts down into the water searching for oil (incredibly loud)
What is CO?
asphyxiant = suffocation
what are the two culprits of acid rain?
H2SO4
HNO3
what is the BIGGEST culprit of acid rain?
H2SO4