Impacts of Car Fuel Efficiency
Improvement on Health through
Reducing Air Pollutants
Qing Shi
July 10th, 2013
Dept. Economics
UNC Greensboro
Contents
Air Pollutants
Health Impacts of air pollutants
Fuel economy of automobiles
Mandates on fuel efficiency of automobiles
Research interests
Data and preliminary results
Air Pollutants and EPA Monitoring
There are numerous air pollutants from natural and human activities
Natural disaster (volcano, fire, etc)
Transportation, construction, power plants, manufacturing, etc.
* Automobile fuel combustion
US Environmental Protection Agency (EPA) monitors six principle air pollutants
Ozone, Particulate Matter, Carbon Monoxide, Nitrogen Oxides, Sulfur Dioxide, Lead
Ambient air concentration and Emission
Physical monitors (instruments) on geographic locations
National Ambient Air Quality Standard (NAAQS – Clean Air Act 1990)
EPA Air Quality System (AQS) (data and analytic applications)
Air Pollutants from Automobiles (Transportation)
Emission (from Fuel Combustion)
Carbon Dioxide (CO2) --- Global Warming (catastrophic, abrupt climate change, increase
spread of tropical disease), indirect health impacts
Water(H2O) --- Help form hydrocarbons (HC), generate PM2.5
Carbon Monoxide (CO)
Nitrogen Oxides (NOx)
Particulate Matter (PM) --- secondary from mixture above and other
Lead (tinny from automobiles in US and EU, mainly from Aviation)
Non-emission (worn particles of tire tread and brake linings)
Heavy metals cadmium (Cd), chrome (Cr), nickel(Ni), lead (Pb) and arsenic (As),
Contribute to PM10 (~67%)
Impacts of air pollutants on health
US EPA
• Respiratory (air way) inflammation, irritation, allergic reactions
• Cough, breath difficulty, damage to lung or air way
• Increase symptoms of asthma, emphysema, and bronchitis, etc
• Adverse effects on nervous system
• Developmental damage to youth
• Organ damage (heavy metals)
• Genetic mutation and carcinogenesis (long term exposure)
• Death (toxic air pollutants)
Pollutant
Main source
Health impact
Carbon Monoxide (CO)
Emitted from combustion •
processes (mobile source
•
mainly, > 90%)
Nitrogen Oxides (NOx)
Emissions from cars,
trucks and buses, power
plants, and off-road
equipment
•
Adverse respiratory effects including airway inflammation and
increases respiratory symptoms (asthma, emphysema and bronchitis)
Originate from natural
processes, human
activities, car emissions,
and construction
•
Irritation of the airways, coughing, and difficulty breathing.
Reduced lung function, Aggravated asthma, Chronic bronchitis
•
Irregular heartbeat, Nonfatal heart attacks
•
Some cancers
•
Hits people with lung disease, children, older adults, active
outdoorers
Reduce lung function and increase respiratory symptoms (asthma,
bronchitis, emphysema), and infections
Trigger a variety of health problems including chest pain,
coughing, throat irritation, and congestion
Particulate Matter (PM)
•
•
PM2.5 (2.5mm)
PM10 (10 mm)
Ozone (O3, ground level)
Chemical reactions
between oxides of
nitrogen (NOx) and
volatile organic
compounds (VOC)
Harmful health effects by reducing oxygen delivery through blood,
may cause myocardial ischemia
Death at extreme level
(Form Ozone)
•
•
Sulfur Dioxide(SO2)
Fossil fuel combustion at Adverse respiratory effects including bronchoconstriction and
power plants (73%) and increased asthma symptoms
other industrial facilities
(Form PM)
(20%)
Lead (Pb)
Near lead smelters
Air plane piston-engine
•
Adversely affect the nervous system, kidney function, immune
system, reproductive and developmental systems and the
cardiovascular system
•
Developmental deficits in youth
Efforts in Reducing Mobile Source Air Pollutants
Emission
Reduce toxic contents (Unleaded fuel)
Raise Emission standards
Fuel consumption
Pricing/Taxation on fuel --- (fuel is relatively inelastic ? )
Fuel efficient cars* --- reducing unit travel fuel consumption
Alternative fuel --- Ethanol, biodiesel,
Hybrid cars
Crude Oil Price and Vehicle Usage
350
300
250
Per Capita Miles (kMiles)
200
Nominal Price ($/Barrel)
150
[1]
[2]
Inflation Adjusted Price ($/Barrel)
100
[3]
1.00000
-0.91257
<.0001
-0.89279
<.0001
-0.91257
<.0001
1.00000
0.99727
<.0001
-0.89279
<.0001
0.99727
<.0001
1.00000
2004
2006
50
0
1994
1996
1998
2000
Data sources:
[1] US DOT Highway Statistics
[2] US DOL Bureau of Labor Statistics
2002
2008
2010
2012
Importance of Fuel Efficient Automobiles
American depend heavily on cars in daily activities
US has more cars than any country else in the world
0.797 car p.c, 2010 World Bank data
Largest crude oil consumer
18.55 m. Barrels (29% more than Europe, 81% more than China), 2012 US EIA Data
Oil is non-recyclable natural resource
Driving emits pollutants (Dusts, CO, NO2) and CO2
Pollutants hurt human health
CO2 contributes global warming
Mandates on Vehicle Fuel Efficiency
Fuel efficient car benefits
less fuel expenditure --- primary goal
less emission (pollutants to the air) due to reducing fuel consumption
better environment and health outcome
Corporate Average Fuel Economy (CAFE)
Enact in 1975 to reduce the consumption of oil through vehicle fuel efficiency
Set 27.5 MPG for passenger cars and 20.7 fro light trucks from 1985
~32 MPG
25 MPG
Weaken in Reagan and Bush Administration
strengthen in Clinton and Bush Administration
from 2012
Improvements in Vehicle Fuel Efficiency
Average US Light Duty Vehicle Fuel Efficiency
MPG
30.0
20.0
One-the-Road Passenger Cars
10.0
On-the-road Light Trucks
New Passenger Cars
New Light Trucks
0.0
1978
1986
1994
2002
2010
Year
Data source: US DOT NTS
Motivations of Research
Does more and more fuel efficient cars on the road make less pollutants?
Will this have good health benefits?
Can we quantify analytically?
Policy advice?
Can we establish the following causal links?
More efficient cars
Less Fuel
consumption
Less air pollutants
Better Health Outcome
Approaches
Fuel efficiency improvement over time (MPG measurement)
Air pollutant reduction over time (Air quality measurements)
Medical service reduction over time (respiratory disease claims from elders )
Challenge
How to attribute the reduction of air pollutants to improvement of car fuel efficiency
How to attribute reduction of medical claims to reductions of pollutants
Research Aims
1. Proportion of fuel efficient cars over time in the state (or county if
possible) level (US) through vehicle registrations data and determine
Improvement of car fuel efficiency
2. Air quality improvement over time and the association between fuel
and air quality improvements
3. Heath outcome improvement: chronicle respiratory disease (eg.
asthma) among elders, state (county) level number of medical claims
and causal relationship
4. Cost-benefit analysis and policy implications
Econometric model and Estimation Framework
Panel Data Models (state/county, year)
1. Air Pollution on Fuel efficiency
𝑃𝑖𝑖 = 𝑔(𝜑𝐹𝑖𝑖 + 𝛽𝑋𝑖𝑖 ) + 𝜀𝑖 + 𝜎𝑖𝑖
2. Health outcome and Pollution
𝐻𝑖𝑖 = ℎ(𝛿𝑃𝑖𝑖 + 𝛽𝑋𝑖𝑖 ) + 𝜀𝑖 + 𝜎𝑖𝑖
Where F is the measure of fuel efficiency, X is other economic
factor, environmental factor and state level demographics,
economy condition to control for, P is the pollutant measure, H
is the health outcome measure, g(.) is a transformation
function that models either linear or non-linear regression, h(.)
is a transformation function
Data
All data are state (aggregate level)/year panel data
Ranging from 1995 ~ 2011, annual
50 States + 1 Districts
Vehicle registration Data (US DOT Highway Statistics)
numbers and categories of vehicle
Miles travels (by functional system and kind of vehicle)
Fuel Sales/Consumption
Gasoline, Gasohol, Diesel
US GDP data (US BEA)
Per capita, total, manufacturing, non-agriculture ..
Air quality Data (EPA AQS)
NO2, CO, PM2.5, …
Fuel efficiency
MPG = miles travel/fuel volume
aMPG (all fuel combined)
gMPG(gasoline and gasohol)
Preliminary results
Fuel Efficiency and Air Quality Change
Fuel Efficiency and Air Quality Change Over Time
(US Aggregate)
80
Source Data: Fuel Efficiency -- US DOT, derived
Air quality -- US EPA
70
60
50
40
30
MPG
Carbon Monoxide
20
Nitrogen Dioxide
10
PM2.5
0
1994
1996
1998
2000
2002
2004
2006
2008
Note: Scales of y-axis does not necessary reflect the absolute values
2010
2012
Preliminary results
Summary Statistics of Data
Variable
Year
State
Miles per Gallon
(MPG)
N
17 (1995 ~2011)
50
816
Mean
Std
16.43001
1.54603
Carbon Monoxide
Nitrogen Dioxide
PM2.5
GDP
(Million Dollars)
773
766
631
720
5.073998
49.48683
28.83216
245267.4
3.229526
17.91408
7.081231
285936.6
Manufacturing GDP
(Million Dollars)
718
30468.24
33553.24
Non-Agriculture GDP
(Million Dollars)
718
243426.7
283673.9
Per Capita GDP
(Thousand Dollars)
720
39201.54
7240.724
Trucks %
Farm Trucks%
Truck Trailors%
Pickups%
Vans%
SUV%
816
689
816
816
816
816
43.99354
1.668049
0.857585
19.22714
7.985282
11.42
8.624289
2.538825
0.5653424
6.405132
3.194305
4.472487
Source Data: Fuel Efficiency -- US DOT, Air quality -- US EPA
Preliminary results
Model Estimates
Simple Fixed Effect Panel Data Models
yst= X st β + α s + ε st
Where s represents individual state, and t represents year
X: MPG, GDP, and other regressors
A statistically significant negative coefficient on MPG variable
indicates improvement in fuel efficiency improves air quality (by
decreasing the pollutant)
(Note: Alaska, Hawaii and District of Columbia are excluded
from the model)
Fixed Effect Model Estimates I . (no year effect)
Table 1. CO on All Fuels MPG
Predictor
MPG, all fuel
Carbon Monoxide, Second Highest 1-hour Measurement
-0.570****
(0.1288)
-0.558****
(0.1172)
-0.376**
(0.1170)
-0.047
(0.1341)
GDP, non-agriculture
(billion dollars, chained 2005)
GDP, per capita
(thousands dollars, chained
2005)
%truck, all
%bus
%truck/tractor
-0.451****
(0.0420)
-0.296****
(0.0478)
-0.302*
(0.1181)
-0.028
(0.1340)
-0.023****
(0.0028)
-0.014****
(0.0030)
-0.009*
(0.0044)
-0.141*
(0.0592)
-0.180****
(0.0290)
-3.482*
(1.7218)
-0.499****
(0.1218)
-0.217****
(0.0279)
-2.178
(2.0262)
-4.236*
(1.7498)
-3.107
(2.0325)
0.600
(0.3443)
0.016
(0.1312)
0.483
(0.3403)
-0.008
(0.1318)
%pickup
0.398****
(0.0592)
0.406****
(0.0587)
%van
-0.321****
(0.0389)
-0.335****
(0.0396)
%suv
-0.297****
(0.0363)
-0.316****
(0.0336)
%farm trurk
Note: * Significant at 0.05; ** Significant at 0.01 ; *** Significant at 0.001; **** Significant at 0.0001
Fixed Effect Model Estimates
Table 2. NO2 on All Fuels MPG
Predictor
MPG, all fuel
Nitrogen Dioxide, the 98th percentile of the daily max 1-hour measurements
-3.035****
(0.6641)
-3.090****
(0.6459)
-2.007**
(0.6483)
-1.177
(0.7721)
GDP, non-agriculture
(billion dollars, chained 2005)
GDP, per capita
(thousands dollars, chained
2005)
%truck, all
%bus
-1.230****
(0.2164)
-0.469
(0.2439)
-2.766****
(0.6441)
-1.893**
(0.6387)
-1.357
(0.7634)
-0.091****
(0.0148)
-0.051****
(0.0160)
-0.038
(0.0247)
-0.099
(0.3100)
-0.985****
(0.1606)
-21.494*
(9.7097)
-0.926****
(0.1533)
-24.988*
(11.8145)
-22.521*
(9.6640)
-26.574*
(11.8300)
%truck/tractor
0.828
(2.0088)
0.637
(1.9562)
%farm trurk
-0.509
(0.7517)
-0.544
(0.7526)
%pickup
1.270****
(0.3412)
1.173***
(0.3368)
%van
-1.384****
(0.2258)
-1.251****
(0.2346)
%suv
-0.959****
(0.2094)
-0.844****
(0.1972)
Note: * Significant at 0.05; ** Significant at 0.01 ; *** Significant at 0.001; **** Significant at 0.0001
Fixed Effect Model Estimates
Table 3. PM2.5 on All Fuels MPG
Predictor
MPG, all fuel
PM2.5, the 98th percentile of the daily average measurements
-1.288****
(0.2758)
-1.269****
(0.2656)
-0.658**
(0.2504)
0.064
(0.2829)
GDP, non-agriculture
(billion dollars, chained 2005)
GDP, per capita
(thousands dollars, chained
2005)
%truck, all
%bus
%truck/tractor
%farm trurk
-0.588****
(0.0867)
-0.091
(0.0924)
-0.659**
(0.2458)
-0.034
(0.2827)
-0.051****
(0.0062)
-0.025****
(0.0063)
-0.006
(0.0094)
0.099
(0.1118)
-0.656****
(0.0622)
-6.909
(3.7757)
-1.138****
(0.2603)
-0.581****
(0.0586)
-0.908
(4.3413)
-0.111
(0.7318)
0.017
(0.2816)
-6.970
(3.7287)
-0.444
(4.3515)
0.011
(0.7125)
0.020
(0.2824)
%pickup
0.754****
(0.1262)
0.709****
(0.1246)
%van
-0.690****
(0.0817)
-0.623****
(0.0845)
%suv
-0.701****
(0.0756)
-0.638
(0.0711)
Note: * Significant at 0.05; ** Significant at 0.01 ; *** Significant at 0.001; **** Significant at 0.0001
Fixed Effect Model Estimates II . (with year effect)
Table 4. CO on All Fuels MPG
Predictor
MPG, all fuel
Carbon Monoxide, Second Highest 1-hour Measurement
0.031
(0.1099)
-0.003
(0.1128)
0.022
(0.1123)
0.013
(0.1353)
GDP
GDP, manufacturing
GDP, non-agriculture
GDP, per capita
-0.074
(0.0559)
-0.080
(0.0555)
%truck, all
0.093**
(0.0353)
%bus
-2.276
(1.5857)
0.024
(0.1107)
0.051
(0.1102)
0.032
(0.1345)
-0.002
(0.0028)
-0.003
(0.0028)
-0.005
(0.0045)
-0.104
(0.0721)
0.093**
(0.0355)
-2.656
(1.9975)
-2.358
(1.6000)
-3.368
(1.9908)
%truck/tractor
0.796*
(0.3579)
0.720*
(0.3519)
%farm trurk
0.007
(0.1281)
-0.009
(0.1285)
%pickup
0.211**
(0.0744)
0.197**
(0.0740)
%van
-0.061
(0.0896)
-0.055
(0.0903)
%suv
-0.181**
(0.0645)
-0.176**
(0.0644)
Note: * Significant at 0.05; ** Significant at 0.01 ; *** Significant at 0.001; **** Significant at 0.0001
Fixed Effect Model Estimates II . (with year effect)
Table 5. NO2 on All Fuels MPG
Predictor
MPG, all fuel
Nitrogen Dioxide, the 98th percentile of the daily max 1-hour measurements
-1.016
(0.6466)
-0.854
(0.6692)
-0.779
(0.6704)
-0.605
(0.7864)
-1.111
(0.6499)
-1.023
(0.6510)
-1.048
(0.7742)
-0.023
(0.0168)
-0.025
(0.0168)
-0.021
(0.0256)
GDP
GDP, manufacturing
GDP, non-agriculture
GDP, per capita
0.283
(0.3021)
0.264
(0.3020)
%truck, all
-0.055
(0.2216)
%bus
-17.945
(9.7532)
0.515
(0.3739)
-0.055
(0.2217)
-27.609*
(11.7196)
-18.713
(9.8204)
-25.674*
(11.7260)
%truck/tractor
-0.713
(2.1568)
0.082
(2.0803)
%farm trurk
-0.609
(0.7395)
-0.612
(0.7434)
%pickup
0.160
(0.4395)
0.245
(0.4363)
%van
-0.933
(0.5118)
-0.903
(0.5165)
%suv
0.313
(0.4055)
0.254
(0.4038)
Note: * Significant at 0.05; ** Significant at 0.01 ; *** Significant at 0.001; **** Significant at 0.0001
Fixed Effect Model Estimates II . (with year effect)
Table 6. PM2.5 on All Fuels MPG
Predictor
MPG, all fuel
PM2.5, the 98th percentile of the daily average measurements
0.117
(0.2258)
0.287
(0.2316)
0.280
(0.2323)
0.478
(0.2538)
0.058
(0.2261)
0.059
(0.2267)
0.299
(0.2538)
-0.013*
(0.0059)
-0.013*
(0.0060)
0.002
(0.0086)
GDP
GDP, manufacturing
GDP, non-agriculture
GDP, per capita
0.303**
(0.1032)
0.295**
(0.1032)
%truck, all
-0.104
(0.0735)
%bus
-3.959
(3.3520)
0.344**
(0.1201)
-0.102
(0.0737)
-3.447
(3.8044)
-4.329
(3.3803)
-1.614
(3.8289)
%truck/tractor
0.377
(0.6790)
0.853
(0.6623)
%farm trurk
-0.039
(0.2445)
-0.023
(0.2473)
%pickup
-0.013
(0.1410)
0.043
(0.1412)
%van
0.232
(0.1709)
0.225
(0.1736)
%suv
-0.173
(0.1226)
-0.215
(0.1229)
Note: * Significant at 0.05; ** Significant at 0.01 ; *** Significant at 0.001; **** Significant at 0.0001
Preliminary Results
1. Improvement in Fuel Efficiency
2. Improvement in Air Quality
3. Association between Fuel Efficiency and Air Quality
Future Direction
1. Causal Links
2. Categorize cars by type, average age of cars
3. County level registration
4. County Level Air quality, control for population
5. Medical data and relationship