The uncertainties of air pollutant emissions in recent years' NEI

NEI Modeling Platform
1

Hi all,

Are there any official papers or documents that quantify the uncertainties of air pollutant emissions in NEI from recent years? I need quantitative values for the uncertainty of different species, utilizing methods such as Monte Carlo simulations. I could only find a few resources such as https://www.tandfonline.com/doi/epdf/10.1080/10962247.2019.1629363?needAccess=true.

Thank you for your time!

2

To the best of our knowledge, there are not any assessments of uncertainty of EPA’s National Emissions Inventory (NEI) estimates in a quantitative sense. There are some items related to uncertainty of sector based emissions in past documents published and available via the gray literature.

At EPA, we do not estimate any uncertainties associated with NEI estimates, other than to talk in general terms in our Technical Support Documents, sector by sector.

However, in the past, several organizations have suggested ways to handle uncertainty in emissions inventories, both qualitatively and semi-quantitatively. Very few, if any, of these studies are for recent years:

  • The National Research Council (NRC) has made numerous recommendations regarding quantification of uncertainty in emissions estimates and emission inventories, including but not limited to the NRC (1991) report on urban and regional air quality, the NRC (1994) report on science and judgment in risk assessment, and the NRC (2000) report on modeling mobile source emissions. [Ref 1, Ref 2, Ref 3]

  • The NARSTO emission inventory assessment has recommended quantitative approaches to uncertainty and sensitivity analysis of emission inventories and provides an extensive literature and overview of practical methods. [Ref 4]

  • The NARSTO emission inventory assessment also lists 2 different quantitative ways to develop uncertainty estimates for inventories. One method involves assigning probability distributions for inputs to an inventory and testing outputs through a “Monte-Carlo” simulation. However, when relevant data are not available, then the direct use of available data can lead to biases in the assessment. An alternative for this kind of situation is to use a “Bayesian” approach to statistical estimation, in which both data and expert judgment can be combined. [Ref 10] provides an example of a “Bayesian” approach to estimating uncertainties in an inventory.

  • The Intergovernmental Panel on Climate Change (IPCC) has developed and refined guidance on quantification of uncertainty in national greenhouse gas emission inventories, including the IPCC Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories (IPCC, 2000) and IPCC Guidelines for National Greenhouse Gas Inventories (IPCC, 2006). [Ref 5, Ref 6]

  • A report by the EPA Office of the Inspector General makes specific recommendations on how EPA’s Office of Air and Radiation (EPA, 2006) should handle uncertainties associated with emission factors. [Ref 7]

In addition, techniques for quantifying uncertainties for some sectors are available in the literature [Ref 8, Ref 9].

References:

  1. NRC (1991), Rethinking the Ozone Problem in Urban and Regional Air Pollution, National Academy Press: Washington (Rethinking the Ozone Problem in Urban and Regional Air Pollution | The National Academies Press).
  2. NRC (1994), Science and Judgment in Risk Assessment, National Academy Press: Washington (Science and Judgment in Risk Assessment | The National Academies Press).
  3. NRC (2000), Modeling Mobile Source Emissions, National Academy Press: Washington (http://books.nap.edu/catalog.php?record_id=9857)
  4. NARSTO (2005), “Improving Emission Inventories for Effective Air Quality Management Across North America,” NARSTO-05-001, NARSTO. http://www.narsto.org/section.src?SID=8
  5. IPCC (2000), “Quantifying Uncertainties in Practice,” Chapter 6 in Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories, National Greenhouse Gas Inventories Programme, Inter-Governmental Panel on Climate Change, Technical Support Unit, 16 Kanagawa, Japan (http://www.ipcc-nggip.iges.or.jp/public/gp/english/6_Uncertainty.pdf.
  6. IPCC (2006), “Uncertainties,” Chapter 3 in Volume 1, General Guidance and Reporting, 2006 IPCC Guidelines for National Greenhouse Gas Inventories, National Greenhouse Gas Inventories Programme, Inter-Governmental Panel on Climate Change, Technical Support Unit, Kanagawa, Japan, 2006. http://www.ipcc-nggip.iges.or.jp/public/2006gl/vol1.htm.
  7. EPA (2006), “Evaluation Report: EPA Can Improve Emissions Factors Development and Management,” 2006-P-00017, Office of Inspector General, U.S. Environmental Protection Agency, Washington, DC., March 22, 2006 http://www.epa.gov/oig/reports/2006/20060322-2006-P-00017.pdf.
  8. Cullen, A.C., and H.C. Frey (1999). The Use of Probabilistic Techniques in Exposure Assessment: A Handbook for Dealing with Variability and Uncertainty in Models and Inputs. Plenum: New York, 1999
  9. Frey, H.C., and S. Bammi (2002), “Quantification of Variability and Uncertainty in Lawn and Garden Equipment NOx and Total Hydrocarbon Emission Factors,” Journal of the Air & Waste Management Association, 52(4):435-448 (April 2002).
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Thanks for the detailed explanation. It really helped me out!