Western Air: Progress and Challenges in
Protecting Human Health and Scenic Vistas
Chancellor’s Community Lecture Series
Healing the West
Mike Hannigan and Jana Milford
Department of Mechanical Engineering
University of Colorado at Boulder
November 6, 2002
Acknowledgments
• Pat Reddy, Colorado Department of Public Health and
Environment
• Pat McGraw, Colorado Department of Public Health and
Environment
•
•
•
•
Chris Shaver, National Park Service
Jaime Lehner, Environmental Engineering, CU-Boulder
Kelly Allard, Environmental Engineering, CU-Boulder
Toni Newville, Mechanical Engineering, CU-Boulder
Road Map
Air Pollution and Health
• Health-based standards
• How is Denver doing?
• The latest challenge:
–Fine particles
Photo credit:
Shelly Miller
Road Map
Air Pollution and Visibility
• Visibility goals
• How is Denver doing?
• How are scenic areas in the West doing?
• What will it take to meet our visibility goals?
Air Quality Standards and Goals
• National Ambient Air Quality Standards – criteria pollutants
• Protect public health and welfare “with an adequate margin of
safety”
– Meant to protect sensitive populations
– Margin of safety concept is questionable if no clear
threshold exists (e.g., particulate matter)
• Set by EPA administrator based on scientific data
– field observations (particulate matter)
– experimental data (ozone)
• Standards to be set without regard to costs
– Costs considered in implementation policies and timelines
• Hazardous air pollutants – 1990 Amendments
– 189 compounds
– Goal: less than one in a million residual risk
National Ambient Air Quality Standards
Carbon Monoxide (CO)
9 ppm, 8-hr
35 ppm, 1-hr
Ozone (O3)
0.12 ppm, 1-hr
0.08 ppm, 8-hr (1997)
Particulate Matter < 10 mm
diameter (PM10)
50 mg/m3, annual
150 mg/m3, 24-hr
Particulate Matter < 2.5 mm 15 mg/m3, annual (1997)
diameter (PM2.5)
65 mg/m3, 24-hr (1997)
Air Quality Standard Exceedances in the Denver Area
Days per Year/Percent of Days
70
CO
PM10
Visibility (%)
60
50
40
30
20
10
0
1986
1988
1990
1992
1994
Year
1996
1998
2000
2002
4th Highest 8-hr Ozone at Denver Area Monitors
100
90
Standard = 80 ppb
80
Ozone (ppb)
70
60
50
40
30
NREL
Rocky Flats
S. Boulder Creek
20
10
0
1994
1995
1996
1997
1998
1999
Year
Violation: 3-yr average > 85 ppb
2000
2001
2002
2003
Size Distribution of Airborne PM
fine
amount
coarse
ultrafine
0.02
2.5
0.1
size
(diameter in mm)
10
How small is that?
10,000 mm = 1 cm
If we zoom in,
human hair
coarse particle
fine particle
ultrafine particle
.
Size Distribution of Airborne PM
coagulation
PM Origins
fine
coarse
#
mechanical processes
ultrafine
0.02
0.1
2.5
10
•
•
•
•
wind blown dust
road sand
brake wear
leaf debris
size
(diameter in mm)
condensation processes
• atmospheric reactions
• combustion
accumulation processes
• coagulation
• condensation on existing particles
√ combustion and atmospheric reactions
Vocabulary
Size Distribution of Airborne PM
fine
coarse
#
ultrafine
0.02
0.1
2.5
size
(diameter in mm)
PM2.5
includes …
…
10 includes
10
So, what happens when breathe these particles in?
Lungs are a series of these branches.
~7 in all, each getting smaller.
coarse particle
So, what happens when breathe these particles in?
Lungs are a series of these branches.
~7 in all, each getting smaller.
.
ultrafine particle
Fine particles go deep into lungs, so this worries us.
OK, so how bad is it?
Acute effects.
Results from the 6-cities study.
Increases in ozone not associated with increases in death.
Increases in PM2.5 are associated with increases in death.
SO, high PM2.5 levels can cause immediate health problems.
Dockery et al., N. Engl. J. Med., 329:1753-1759.
Total Mortality
Chronic effects
1.00 means no increased risk
Relative Risk
Cardiopulmonary Mortality
Lung Cancer Mortality
Other Mortality
There is significant risk of death
from cardiopulmonary problems
and lung cancer due to PM2.5
levels in the US urban areas.
If you live in a US urban area, the risk
associated with PM2.5 is similar to the
risk of being moderately overweight.
Pope et al., JAMA, 287: 1132-1141, 2002
PM2.5 Annual Trends for Front Range
20
18
16
14
Boulder
Downtown
m g/m3
12
10
Commerce City
Greeley
8
6
4
2
0
1999
2000
2001
Hard to say much about trends with any degree of confidence.
If we were to use the numbers from
Total = 3500 deaths/year
that study, along with western air
(1200-6200 – 95% confidence)
pollution values …
(50)
(100)
(310)
(110)
(860)
(450)
(200)
(1560)
Contributions to PM2.5 Mass
(Los Angeles, 1993)
Los Angeles
So, can we be more specific
about the origin of PM2.5?
Contributions to PM2.5 Mass
(Denver, Winter 1997)
Differences may be due
to technique.
diesel exhaust
Denver
gasoline exhaust
tire wear
road dust
vegetative debris
cigarette smoke
natural gas combustion
meat cooking
wood smoke
sulfate
Still motor vehicles are King!
nitrate
ammonium
other
Source: NFRAQS (1999)
Visibility:
Downtown Denver
Grand Canyon National Park
Visibility Goals
• Regional Haze
– 1977 Clean Air Act Amendments
Set goal of returning visual air quality to natural
conditions in 156 National Parks and Wilderness Areas
– 1990 Clean Air Act Amendments
Emphasized regional nature of problem
– 1999 Regional Haze Rule:
Return to natural visibility conditions by 2065
• Denver-Metro Visibility Standard
– State standard, established in early 1990s
– Set by study of Denver residents’ views on acceptable visual
air quality
– Not federally enforceable
uv
x-rays
infrared
radar
visible
1 nm
10 nm
100 nm 1 mm
microwave
10 mm 100 mm
1 mm
radio
tv
1 cm
1m
100 m
1 km
wavelength
Why do we call this
energy type ‘visible’?
We can see it!
So, what does that
make our eyes?
Highly evolved
energy detectors.
200 nm
800 nm
1 mm
Size distribution of energy from the sun
2 mm
Now, overlay the solar energy size distribution over the typical particle size distribution.
Size Distribution of Airborne PM
#
0.02
0.1
(mm)
2.5
10
Fine particles are similar in size to visible light, and, in general, the solar spectrum.
SO, these particles impact visibility and solar radiation.
One-hour extinction at 3 PM = 0.026 km-1
(standard = 4-hour average of 0.076 km-1)
Photo courtesy of Pat Reddy, CDPHE
One-hour extinction at 1 PM = 0.078 km-1
(standard = 4-hour average of 0.076 km-1)
Photo courtesy of Pat Reddy, CDPHE
One-hour extinction at 11 AM = 0.682 km-1
(standard = 4-hour average of 0.076 km-1)
Photo courtesy of Pat Reddy, CDPHE
Air Quality Standard Exceedances in the Denver Area
Days per Year/Percent of Days
70
CO
PM10
Visibility (%)
60
50
40
30
20
10
0
1986
1988
1990
1992
1994
Year
1996
1998
2000
2002
Grand Canyon
National Park
Mount Trumbull viewpoint
Bext = .041 km-1
Visual Range = 95 km
Bext = .010 km-1
Visual Range = 390 km
Source: IMPROVE
network
Visibility Trends at Grand Canyon National Park
Source: U.S. EPA
Weiminuche
Wilderness
Bext = .011 km-1
PM2.5 = 0.2 ug/m3
Bext = .130 km-1
PM2.5 = 23.6 ug/m3
Source: IMPROVE
network
Visibility Trends at Weiminuche Wilderness Area
Source: U.S. EPA
Weiminuche PM2.5 Mass
Fine Soil
21%
Sulfate
35%
Weiminuche Extinction
Elemental Carbon
7%
Organic Carbon
32%
Nitrate
5%
Fine Soil
18%
Sulfate
43%
Elemental Carbon
11%
Organic Carbon
22%
Nitrate
6%
Source: Ames (2001) National Park Service
coarse/10
soil
EC
OC
Grand Canyon
Weiminuche
Natural (estimate)
nitrate
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
sulfate
Concentration ( m g/m3)
How do we get to natural visibility?
Emissions = Population
x Demand
x Emissions Rate
x Control Efficiency
So what will it take to return visibility in the
West to natural conditions?
Population Projections
Source: U.S. Census Bureau (2002)
60,000
Population (thousands)
50,000
1995
2000
2005
2015
2025
Texas
Utah
40,000
30,000
20,000
10,000
0
Arizona California Colorado
Florida
Idaho
Montana
Nevada
New
Mexico
New
York
Wyoming
Energy Use by Sector - Mountain States
Source: EIA (2002)
AZ, CO, ID, MT, NV, NM, UT, WY
10
9
Mtn 2000
Quadrillion Btu per Year
8
Mtn 2015
7
6
5
4
3
2
1
0
Residential
Commercial
Industrial
Transportation
Total
Projected Baseline Emissions - Western States
Source: Western Regional Air Partnership (2002)
4.5E+06
Off-Road
4.0E+06
On-Road
3.5E+06
Other Points
Tons per Year
3.0E+06
Smelter
2.5E+06
Utility
2.0E+06
1.5E+06
1.0E+06
5.0E+05
0.0E+00
NOx - 1996
NOx - 2018
SO2 - 1996
SO2 - 2018
Conclusions
• Since Denver is now in compliance with federal air standards, is
our health protected?
– Ozone attainment is borderline
– PM2.5 health effects may occur below the standard – no clear threshold
• Why can we still see the Brown Cloud?
– Fine particles haven’t been aggressively controlled
• Are pollutants that affect visibility in the national parks the same
ones that affect health in urban areas?
– Fine particles degrade visibility and cause health effects
• Is visibility in national parks and wilderness areas in the West
improving or getting worse?
– No strong trends. Overall in the West, clearest days are getting clearer, no
change in worst days.
What do you think?
• Should we go further to improve air
quality in the Front Range?
• How far should we go to restore visibility
in scenic areas to natural conditions?