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?