Transcript Slide 1
Multipollutant Air Quality Management: A Critical Review George M. Hidy William T. Pennell A&WMA 103rd Annual Conference and Exhibition Calgary, Alberta, Canada June 23,2010 Introduction and Overview Motivation: 2004 NRC Assessment Air Quality Management in the United States --NARSTO evaluated and extended the concept for North America Current practice constrains our ability to meet future challenges: • Increasingly strict ambient standards • Health effects of air toxics—integrated with criteria pollutants • Apparent lack of risk thresholds • Environmental justice and “hot-spots” • Ecosystem effects • Regional influence and long-range transport • Climate change System could evolve to one that strives to-• Identify the most significant cumulative exposures, risks, and uncertainties based on pollutant mixtures. • Take a multipollutant approach to controlling emissions that pose the most significant risks • Take an airshed-based approach optimizing pollutant reductions to minimize exposure risk to multipollutants arising from local, regional, national, and international sources • Emphasize results over process, create a system for evaluating the effectiveness of control measures, and dynamically adjust and correct actions as they are implemented Charge to Assessment Team • Assess the state of knowledge and the multipollutant assessment tools for achieving a risk-based air quality management approach that incorporates means for assessing the effectiveness of management actions (accountability) • Provide recommendations for enhancement of capabilities and knowledge needing improvement Assessment Chairs and Expertise • • • • George Hidy (Envair/Aerochem) Jeff Brook (Environment Canada) Ken Demerjian (State University of New York at Albany) Luisa Molina (MIT and Molina Center for Energy and the Environment) • Rich Scheffe (EPA) • Bill Pennell (NARSTO -ex-officio) • A large group of contributors in the relevant sciences. Approach • Query health and ecosystem effects scientists regarding their information needs for risk reduction from multipollutant exposure – Vital information for estimating exposure and dose – Improved effects exposure-response; especially the effects of exposure to pollutant mixtures • Assess the ability of the atmosphericenvironmental sciences to meet these needs – Existing resources – Improved methods (chemical characterization, modeling and monitoring) for assessing exposure – Improved information on emissions and atmospheric composition at point of exposure Features of Risk- and Results-Based Air Quality Management • Administrative coordination – All air pollutants and climate-forcing agents considered in concert – Reviews of standards coordinated and placed on compatible schedules – Plans for achieving goals coordinated • Risk-based decision making – Priority on reducing exposures that represent the greatest risks • Accountability Transitioning to a Risk- and Results-Based Approach • Level 1: focus on attainment of individual ambient standards • Level 2: attainment of individual standards, but with increasing attention to co-benefits from coordinated emissions reductions • Level 3: decisions based on achieving greatest risk reduction based on single-pollutant exposure-doseresponse relationships • Level 4: decisions based on achieving greatest risk reduction based on multipollutant exposure-doseresponse relationships Where Are We Now? • Level 2 is clearly achievable -- given appropriate planning and resources • Level 3 is attainable given significant improvements in exposure characterization, but determination of relative risk is problematic unless there are significant differences pollutant exposure and potency • Attaining Level 4 will require substantial advances in our understanding of the consequences of exposure to multiple pollutants and our ability to simplify multipollutant exposure assessment Accounting for Problems of “Global” Change Future air quality management could be complicated by three global-scale influences • Large -scale Transport of long-lived pollutants or pollutant precursors resulting from increased global emissions • Changes in emissions resulting from actions taken to mitigate anthropogenic climate change, including substitution of technologies • Changes in atmospheric chemistry, biogenic emissions, and meteorological conditions resulting from climate change— climate change increasingly included in pollutant regulation? These factors could affect strategies for managing air quality, but current estimates of impacts are “small” and extend to a long term (> 50 years). The “Climate Penalty” Tools and Priorities Management Options (Policy) Emissions Risk Characterization Valuation Ecosystem Exposure Ecosystem Effects Air Quality Human Exposure Global Change Human Health Effects Examples The Toolbox for Multipollutant Strategies • Tools to support multipollutant AQ strategies are well known with understanding of – – Atmospheric Physicochemical Processes • Multipollutants derive from sources and atmospheric chemistry – Measurements of Ambient Concentrations and Exposure Estimation • What’s there is fundamental! Criteria and Toxics – Emissions Characterization • Primary sources –magnitude, location, reactivity and futures – System or Air Quality Modeling • Present and future space and time – Linking Exposure to Effects • Exposure (Concentration) and Response Humans and Ecosystems Integrating Complexity for Relative Risk Environmental Variables: Solar Radiation, Temperature, Relative Humidity Light Absorbing Photolytic CP – HAPS Precursor Phase: Gas/Aerosol Targeted Functional Groups Thermal Dissociation Particle Size Water Solubility Chemical Lifetime Reactivity Analysis of Relative Risk – Priority Setting • The Current Approach Deals with Pollutants Separately. – Formal Risk Analysis Methods Exist, but are Data Limited. • A Risk-Based Framework Needs to be Able to Differentiate Risks for Priority Setting. • What Are the Criteria? – Population vs. Individual Risk – Cost and Benefit • What’s Missing? – Dose-Response of mixtures? – Critical Elements—Toxicity and Concentration or Exposure? • Are There Practical Measures for Risk Priorities Within the Present Regulatory Frameworks? – Some Demonstrations Focused on Cost-Benefit Accountability is Important Parallelism Between Risk Analysis, AQ Management and Accountability Paradigm Goal Setting Emissions Strategy Emiss. Inv. Exposure Audit Action Emiss. Change Model exposure Effects Ambient Measure Effects Exposure Effects How Far Can We Take Accountability • Accountability is a Sequence of Assessment Beginning with Emissions, Tracing through Ambient Exposure Conditions to health or Ecological Response • Do Changes in Emissions Result in Improvements in Public Health? • Examples can be extracted from Records of Progress. – Ozone and Oxidants – Particles – HAPs, including Mercury Trends in O3 –Los Angeles Trends in Ambient Ozone 100 900 90 800 80 700 70 600 60 500 50 400 40 300 30 200 20 100 10 0 0 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 Year Mean Annual 4th Max O3 EGU NOx Emissions EGU NOx Emissions (1000 tons per year) Mean Annual 4th Highest O3 (ppbv) Regional O3 (AL,GA,MS, FL) Don’t Follow NOx Emissions or NMHC Emissions Changes The Case of Particulate Matter • Trends in Emissions and Ambient Concentration • Outdoor Concentrations are exposure – Exposure complexity – Some PM is IndoorOutdoor • Some PM is Not • Assume Outdoor a Surrogate! • Health Effects and PMx – Intervention Experiments – Historical Health Change PM Health Effects—Response to Change • Accountability—The End Game • Intervention Studies – – – – – A Series of Studies Utah Steel Mill Shutdown (Pope et al, 1989;Ghio, 2004) U. S. Southwest- 1960s Smelter Strike (Pope et al., 2007) Hong Kong Fuel Switch (Hedley et al., 2002) Dublin Coal Use (Clancy et al., 2002) • Long Term Changes with Ambient Air Quality – Reanalysis of the 6 Cities Study (Laden et al., 2006) – PM2.5 and Life Expectancy (Pope et al., 2009) Opportunities for Multipollutant Management • Working within the Current Regulations – Streamlining Administrative Direction, including Adjusting Parallel Schedules for Implementing Emission Reductions. – Expand Knowledge of Emissions and Air Chemistry to Integrate Criteria Pollutants and Air Toxics. – Use Risk-Based Goal Setting--Support with More Systematic Concentration --Response Portfolio. – Encourage Prescription of Accountability Chain in Regulatory Process. – Incorporate Feedback from Accountability Analyses into Planning and Implementing Strategies, including Progressive Changes. For the Future • Develop a Framework for Grouping Pollutants within Common sources, Chemistry and Biological Response for Addressing Strategies. • Test Concepts for Risk Prioritization and Adopt These in Complex Emission Reduction Strategies. • Establish Refined Health and Ecological Effects Programs to Address Relative Risk. • Explore Improving Opportunities to Obtain Management Relevant Feedback from the Accountability Chain. • Review Monitoring and Measurement Programs to Estimate Their Effectiveness in Providing Multipollutant Characterization Beyond Regulated Pollutants.