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 (O 3 )0.12 ppm, 1-hr 0.08 ppm, 8-hr (1997) Particulate Matter < 10  m diameter (PM10) 50  g/m 3, annual 150  g/m 3, 24-hr Particulate Matter < 2.5  m diameter (PM2.5) 15  g/m 3, annual (1997) 65  g/m 3, 24-hr (1997)

Violation: 3-yr average > 85 ppb

amount size Size Distribution of Airborne PM ultrafine fine coarse (diameter in  m)

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) 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 PM 10 includes …PM 2.5 includes … ultrafine fine coarse (diameter in  m) 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: Results from the 6-cities study. Increases in ozone not associated with increases in death. Increases in PM 2.5 are associated with increases in death. SO, high PM 2.5 levels can cause immediate health problems.

Chronic effects Pope et al., JAMA, 287: , 2002 PM 2. 5 Ozone Total PM Relative Risk 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 PM 2.5 levels in the US urban areas. If you live in a US urban area, the risk associated with PM 2.5 is similar to the risk of being moderately overweight.

Hard to say much about trends with any degree of confidence.

Total = 3500 deaths/year ( – 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 Angeles So, can we be more specific about the origin of PM 2.5 ? 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 cm1 m100 m1 km 1  m 1 nm1 mm 100  m10  m 100 nm10 nm radio visiblevisible uv x-rays infrared radartv 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  m 800 nm Highly evolved energy detectors.

# Size Distribution of Airborne PM (  m) 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 = km -1 (standard = 4-hour average of km -1 ) Photo courtesy of Pat Reddy, CDPHE

One-hour extinction at 1 PM = km -1 (standard = 4-hour average of km -1 ) Photo courtesy of Pat Reddy, CDPHE

One-hour extinction at 11 AM = km -1 (standard = 4-hour average of km -1 ) Photo courtesy of Pat Reddy, CDPHE

Grand Canyon National Park Mount Trumbull viewpoint B ext =.041 km -1 Visual Range = 95 km B ext =.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 B ext =.011 km -1 PM2.5 = 0.2 ug/m 3 B ext =.130 km -1 PM2.5 = 23.6 ug/m 3

Source: U.S. EPA Visibility Trends at Weiminuche Wilderness Area

How do we get to natural visibility? 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?

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?