Transcript Air Quality Mobile - Northern Arizona University

Chapter 11
Improving Air Quality:
Controlling Mobile Sources
1. Understanding Urban Air Problems
Measuring Urban Air Quality
• EPA monitors the air in relatively large metropolitan
statistical areas (MSAs) and reports part of its
findings using the ____________________(AQI)
• AQI is reported as the highest of five pollutantspecific index values (ranging between 0 & 500) for
that day and signifies the worst daily air quality in
an urban area over a given time period
– five of the criteria pollutants: PM, SO2, CO, O3, & NO2
– An AQI of 100 is considered to correspond to the
standard set by CAA
Standards for PM-2.5 were added by the EPA in 1997.
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Photochemical Smog in Urban Areas
• Formed from pollutants that chemically react in
sunlight to form new substances
• Principal component is tropospheric (groundlevel) ozone (O3)
– Formed from a chemical reaction of ___ and volatile
organic compounds (_____) and sunlight
– Released by stationary and mobile sources
– Highest emitters of smog precursors among
transportation sources are _________________
Smog can cause eye and nose irritation; it decreases the
lungs' working capacity, causes shortness of breath,
pain when inhaling deeply, coughing…
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2. Controlling Mobile Sources
1990 Clean Air Act Amendments
• 1990 Clean Air Act Amendments
strengthened U.S. controls on motor vehicle
emissions and fuels through _______
• Includes tougher emissions requirements,
fuel quality controls, and incentives to
encourage development of cleaner-running
vehicles and cleaner alternative fuels
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(1) Emissions Reductions
standards on tailpipe emissions
Tier I
• Phased in between 1994 and 1998
• Aimed at reducing emissions of non-methane
hydrocarbons (NMHC), carbon monoxide (CO),
nitrogen oxides (NOx), and particulate matter (PM)
• Passenger cars and light trucks subject to tighter
regulation than heavier SUVs, minivans, pickup trucks
• Stricter controls for initial 5 years or 50,000
miles of use; less stringent controls for
remainder of vehicle’s useful life redefined as
10 years or 100,000 miles
The policy focuses on the manufacture of
these vehicles
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Tier II
• Phased in between 2004 and 2008
• Tougher requirements given for each successive
model year
• Unique to this tier of controls is:
– an interrelated system of controls on vehicles
and fuels
– no distinction for vehicle size
further reductions in pollutant releases
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(2) Fuel Quality Controls
• Prohibits leaded fuel after 1995
• Requires ____________________ in certain
ozone nonattainment areas
– Fuels that emit less hydrocarbons, carbon
monoxide, and toxics than conventional
gasoline
• Requires __________________ in certain CO
nonattainment areas
– Formulations with enhanced oxygen content
to allow for more complete combustion and
hence a reduction in CO emissions
hydrocarbons—an organic compound containing
only carbon and hydrogen, e.g., butane
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(3) Clean Fuel Vehicles
• 1990 amendments established a ___________
_____________________
– A clean fuel vehicle is certified to meet
stringent emission standards for such
pollutants as CO, NOX, PM, and formaldehyde
• In ozone and CO nonattainment areas, a
proportion of new fleet vehicles had to be clean
fuel vehicles and had to use clean alternative
fuels (_____________________________…)
p240
E10—10% ethanol and 90% gasoline;
E85—85% ethanol and 15% gasoline
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3. Economic Analysis of Mobile Source Controls
Policy Characteristics to Analyze
• absence of benefit-cost analysis in setting
emissions standards
• uniformity of auto emissions standards
• inherent bias against new vehicles
• implications of clean fuel alternatives
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(1) Absence of Benefit-Cost Analysis:
An Inefficient Decision Rule
• New standards were _________________, i.e.,
set specifically to compel auto industry to find
solutions
– Perversely gave manufacturers a strong case to seek
adjustments and postponements for compliance
• New standards were ________________
– Set solely to protect public health and welfare
– Implies the standards were set to _________
_____, where MSB = 0 versus to achieve
efficiency, where MSB = MSC
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Benefit-Based Emission Standards
$
MSC
Benefit-based standards imply
abatement at A0 which is higher
than AE. Suggests
_____________ of mobile
sources.
0
AE
MSB
A0
Abatement
where MSB = 0
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(2) Uniformity of Auto Emissions Standards
• With few exceptions, emission standards are
applicable on every model produced with no
regard to where the vehicle will be driven
– This ________________ “clean” areas and
______________ “dirty” areas because MSB in
more polluted regions should be higher than in
cleaner regions, making the efficient abatement
level higher in dirtier regions
• Studies suggest there would be considerable
cost savings if a two-tiered standard replaced
the uniform standard
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Two-tiered Standard
One study shows a $23B
savings over 10 years
$
MSC
MSBdirty
MSBclean
0
ASTclean
ASTdirty
Abatement
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(3) Bias Against New Vehicles
• More stringent controls on new vehicles bias
consumer decisions against new cars
(regulations on new cars add to costs which
elevates relative price)
• As PNewCars , DUsedCars __ (substitutes), which
perversely encourages use of higher-emitting
cars
Regulating new car emissions adds to production
costs of new cars, shifting the supply curve for new
cars to the left and elevating price for new cars from
P1 to P2. Consumers buy more used cars at each price
and shift the demand curve for used cars to the right.
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Bias Against New Vehicles
$
S2
S1
P2
P1
S1
P2
P1
D1
Q2
Q1
New Cars
Q
D1
Q1 Q2
D2
Q
Used Cars
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(4) Implications of Clean Fuel Alternatives
• Advanced fuels are required only in the dirtier
regions of the country
• Since this aligns higher MSC of developing and
using new fuels with higher MSB of cleaning up
in dirtier regions, it may approach an efficient
solution
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Smog
http://en.wikipedia.org/wiki/Smog
• Smog is a kind of air pollution; the word
"smog" is a portmanteau of smoke and fog.
Classic smog results from large amounts of
coal burning in an area caused by a mixture of
smoke and sulfur dioxide. Modern smog does
not usually come from coal but from vehicular
and industrial emissions that are acted on in
the atmosphere by sunlight to form secondary
pollutants that also combine with the primary
emissions to form photochemical smog.
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Smog
• A photochemical smog is the chemical reaction of
sunlight, nitrogen oxides (NOx) and volatile organic
compounds (VOCs) in the atmosphere, which leaves
airborne particles (called particulate matter) and
ground-level ozone.
• Nitrogen oxides are released by nitrogen and oxygen
in the air reacting together under high temperature
such as in the exhaust of fossil fuel-burning engines
in cars, trucks, coal power plants, and industrial
manufacturing factories. VOCs are released from
man-made sources such as gasoline (petrol), paints,
solvents, pesticides, and biogenic sources, such as
pine and citrus tree emissions.
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Smog
•
•
•
•
•
•
•
ground-level ozone
sulfur dioxide
nitrogen oxides (such as nitrogen dioxide)
carbon monoxide
volatile organic compounds (VOCs)
peroxyacyl nitrates (PAN)
aldehydes (R'O)
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Smog
• Characteristic coloration for smog in California
in the beige cloud bank behind Golden Gate
Bridge. The brown coloration is due to the
NOx in the photochemical smog.
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