APES unit 7 Flashcards
(46 cards)
Clean Air Act
identified 6 criteria air pollutants that the EPA (environmental protection agency) is required to set acceptable limits for, monitor and enforce.
6 criteria air pollutants
SO2 Sulfur dioxide
NOx Nitrogen oxides
CO carbon monoxide
PM particulate matter
O3 Ozone
Pb lead
SO2 sources and effects
– coal combustion (electricity)
– respiration irritation, smog, acid precipitation
NOx sources and effects
– all FF combustion (gas esp.)
– O3, photochemical smog, acid precipitation
CO sources and effects
– Incomplete combustion
– O3, lethal to humans
PM sources and effects
– FF/ biomass combustion
– Respiration irritation, smog
O3 sources and effects
– photochemical oxidation of NO2
– respiration irritant, smog, plant damage
Pb sources and effects
– metal plants, waste incineration
– neurotoxic, (nervous system)
Why is CO2 not a criteria air pollutant?
CO2 does not directly lower air quality from a human health stand point:
–is not toxic to organisms to breath,
–not damaging to lungs/ eyes,
–does not lead to smog
It is a GHG and lead to earth warming and thus environmental and human health consequences. (more indirectly than criteria air pollutants)
Coal combustion
releases CO, CO2, SO2, NOx, toxic metals (mercury, arsenic, lead) and PM often carries these)
impacts of SO2
–respiratory irritant (worsens asthma and bronchitis)
– sulfur aerosols (suspended sulfate particles) block sunlight, reducing visibility and photosynthesis
– forms sulfurous (grey) smog
– combines with water and O2 in atm. sulfuric acid leads to acid prec.
nitrogen oxides
(NO)
release by combustion of anything.
– NO forms when N2 combines with O2
– NO can become NO2 by reacting with O3 or O2
– Sunlight converts NO2 back into NO
environmental and human health impacts of NOx
–respiratory irritant
– leads to tropospheric ozone formation which leads to photochemical smog
– combines with water and O2 in atm. to form nitric acid, –acid prec.
EPA and Lead
(cars/gasoline)
(Human health impact of Lead)
Before Clean Air Act, lead was a common gasoline additive, EPA began phaseout of lead from gasoline.
– Vehicles made after 1974 are required to have catalytic converters to reduce NOx, CO and hydrocarbon emissions (lead damages catalytic converters)
– lead is a know neurotoxicant
primary air pollutants
emitted directly from sources such as vehicles, power plants, factories or natural sources
NOx, CO, CO2, VOCs, SO2, PM, hydrocarbons
secondary air pollutants
– primary pollutants that have transformed in presence of sunlight, water, O2
– occur more in day since sunlight
– tropospheric ozone, sulfuric acid and sulfate, nitric acid and nitrite
Normal conditions of temperature of troposphere
warm, cooler, cold
thermal inversion conditions of temperature of troposphere
cooler, warm (inversion layer) , cold
air convection
(during thermal inversion)
because warm air rises, air convection carries air pollutants away from earth’s surface and distributes them higher into the atmosphere
When there is a thermal inversion, convection doesn’t carry pollutants up and away.
thermal inversions are due to______
–due to warm front moving over
–or due to hot urban surfaces cooling overnight while infrared radiation absorbed during the day is still being released.
effects of thermal inversion
(health issue)
(economic)
(environmental)
Air pollutants are trapped closer the earth.
–Respiratory irritation:
asthma flare ups leading to hospitalization, worsened COPD, emphysema
–decr. tourism revenue
–decr. photosynthetic rate.
Pollutants of lightning striking
Convert N2 in atm. to NOx
Pollutants of forest fires
CO, PM, NOx
Combustion of biomass also releases CO2 and H2O vapor (GHG)
Pollutants of plants (esp. conifers)
Plants emit VOCs
EX: Terpenes and Ethylene from pine, fir, spruce trees. This form natural photochemical smog in Smoky Mountains
