Western Air: Progress and Challenges in Protecting Human Health and Scenic Vistas
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Transcript of Western Air: Progress and Challenges in Protecting Human Health and Scenic Vistas
Western Air: Progress and Challenges in Protecting Human Health and Scenic Vistas
Chancellor’s Community Lecture SeriesHealing the West
Mike Hannigan and Jana MilfordDepartment 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 MapAir 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-hr35 ppm, 1-hr
Ozone (O3) 0.12 ppm, 1-hr0.08 ppm, 8-hr (1997)
Particulate Matter < 10 m diameter (PM10)
50 g/m3, annual150 g/m3, 24-hr
Particulate Matter < 2.5 m diameter (PM2.5)
15 g/m3, annual (1997)65 g/m3, 24-hr (1997)
Air Quality Standard Exceedances in the Denver Area
0
10
20
30
40
50
60
70
1986 1988 1990 1992 1994 1996 1998 2000 2002
Year
Day
s pe
r Yea
r/Per
cent
of D
ays
COPM10Visibility (%)
4th Highest 8-hr Ozone at Denver Area Monitors
0
10
20
30
40
50
60
70
80
90
100
1994 1995 1996 1997 1998 1999 2000 2001 2002 2003
Year
Ozo
ne (p
pb)
NRELRocky FlatsS. Boulder Creek
Standard = 80 ppb
Violation: 3-yr average > 85 ppb
amou
nt
size
Size Distribution of Airborne PM
ultrafine
fine
coarse
(diameter in m)
2.50.1 100.02
How small is that?10,000 m = 1 cm
If we zoom in,
human hair
coarse particle
fine particle
.
ultrafine particle
#
size
Size Distribution of Airborne PM
ultrafine
fine
coarse
(diameter in m)
2.50.1 100.02
mechanical processes• wind blown dust• road sand• brake wear• leaf debris
coagulation
condensation processes• atmospheric reactions• combustion
accumulation processes• coagulation• condensation on existing particles√ combustion and atmospheric reactions
PM Origins
#
size
Size Distribution of Airborne PM
PM10 includes …PM2.5 includes …
ultrafine
fine
coarse
(diameter in m)
2.50.1 100.02
Vocabulary
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.
Dockery et al., N. Engl. J. Med., 329:1753-1759.
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.
Chronic effects
Pope et al., JAMA, 287: 1132-1141, 2002
PM2.5
Ozone
Total P
M
Rel
ativ
e R
isk
1.00 means no increased risk
Total Mortality
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.
PM2.5 Annual Trends for Front Range
0
2
4
6
8
10
12
14
16
18
20
1999 2000 2001
g/
m3
BoulderDowntownCommerce CityGreeley
Hard to say much about trends with any degree of confidence.
Total = 3500 deaths/year (1200-6200 – 95% confidence)
If we were to use the numbers from that study, along with western air pollution values …
(310)
(1560)
(110)
(450)(860)
(100)
(200)
(50)
Denver
Los AngelesSo, can we be more specific about the origin of PM2.5?
Contributions to PM2.5 Mass(Denver, Winter 1997)
diesel exhaustgasoline exhausttire wearroad dustvegetative debriscigarette smokenatural gas combustionmeat cookingwood smokesulfatenitrateammoniumother
Contributions to PM2.5 Mass(Los Angeles, 1993)
Differences may be due to technique.
Still motor vehicles are King!
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
wavelength
1 cm 1 m 100 m 1 km1 m1 nm 1 mm100 m10 m100 nm10 nm
radiovisible
uvx-rays
infrared
radar tv
microwave
Why do we call this energy type ‘visible’?
We can see it!
So, what does that make our eyes?
Size distribution of energy from the sun
200 nm 1 m 2 m800 nmHighly evolved energy detectors.
#
Size Distribution of Airborne PM
(m)2.50.1 100.02
Now, overlay the solar energy size distribution over the typical particle size distribution.
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
0
10
20
30
40
50
60
70
1986 1988 1990 1992 1994 1996 1998 2000 2002
Year
Day
s pe
r Yea
r/Per
cent
of D
ays
COPM10Visibility (%)
Grand Canyon National ParkMount Trumbull viewpoint
Bext = .041 km-1
Visual Range = 95 km
Bext = .010 km-1
Visual Range = 390 km
Source: IMPROVE network
Source: U.S. EPA
Visibility Trends at Grand Canyon National Park
Weiminuche Wilderness
Source: IMPROVE network
Bext = .011 km-1
PM2.5 = 0.2 ug/m3
Bext = .130 km-1
PM2.5 = 23.6 ug/m3
Source: U.S. EPA
Visibility Trends at Weiminuche Wilderness Area
Weiminuche PM2.5 Mass
Sulfate35%
Nitrate5%Organic Carbon
32%
Elemental Carbon7%
Fine Soil21%
Weiminuche Extinction
Sulfate43%
Nitrate6%
Organic Carbon22%
Elemental Carbon11%
Fine Soil18%
How do we get to natural visibility?
00.10.20.30.40.50.60.70.80.9
1C
once
ntra
tion
(g/
m3 )
sulfa
te
nitr
ate
OC EC soil
coar
se/1
0
Grand CanyonWeiminucheNatural (estimate)
Source: Ames (2001) National Park Service
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 ProjectionsSource: U.S. Census Bureau (2002)
0
10,000
20,000
30,000
40,000
50,000
60,000
Arizona California Colorado Florida Idaho Montana Nevada NewMexico
NewYork
Texas Utah Wyoming
Popu
latio
n (th
ousa
nds)
1995 2000 2005 2015 2025
Energy Use by Sector - Mountain StatesSource: EIA (2002)
AZ, CO, ID, MT, NV, NM, UT, WY
0
1
2
3
4
5
6
7
8
9
10
Residential Commercial Industrial Transportation Total
Qua
drill
ion
Btu
per
Yea
r
Mtn 2000
Mtn 2015
Projected Baseline Emissions - Western StatesSource: Western Regional Air Partnership (2002)
0.0E+00
5.0E+05
1.0E+06
1.5E+06
2.0E+06
2.5E+06
3.0E+06
3.5E+06
4.0E+06
4.5E+06
NOx - 1996 NOx - 2018 SO2 - 1996 SO2 - 2018
Tons
per
Yea
r
Off-Road
On-Road
Other Points
Smelter
Utility
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?