Embed Size (px)
Citation preview
Outline Attainment demonstrations for PM2.5 Modeled attainment test Analyses related to local primary PM2.5
sources
Attainment Demonstrations CAA Section 172(c) requires States with a
nonattainment area to submit an attainment demonstration
All States must submit attainment demonstrations which include modeling (§51.1007) Emissions inventories (base and future years) Adopted control measures
Ozone/PM2.5/Regional Haze Modeling Guidance
“Guidance on the use of Models and Other Analyses for Demonstrating Attainment of Air Quality Goals for Ozone, PM2.5, and Regional Haze” http://www.epa.gov/scram001/guidance/guide/final-03-pm-rh-guidance.pdf Original draft- January 2001 Draft final- September 2006 Final version- April 2007
What’s in the Guidance? Part I- Using Model Results
Modeled Attainment tests 8-hour ozone NAAQS
Unmonitored area analysis Annual and 24-hour PM2.5 NAAQS
Unmonitored area analysis Local area analysis (high primary PM2.5 areas)
Regional Haze reasonable progress Supplemental analyses/weight of evidence Activities to support Mid-Course review and future
modeling Required documentation
What’s in the Guidance? Part II- Generating Model Results
Conceptual description Modeling protocol Selecting a model(s) Choosing days/episodes Selecting domain & spatial resolution Developing met inputs Developing emissions inputs Evaluating model performance/diagnostic analyses
Modeled Attainment Tests
All O3/PM2.5/RH modeled attainment tests use model estimates in a “relative” sense Premise: models are better at predicting relative
changes in concentrations than absolute concentrations
Relative Response Factors (RRF) are calculated by taking the ratio of the model’s future to current predictions of PM2.5 or ozone
RRFs are calculated for ozone and for each component of PM2.5 and regional haze
Unmonitored Area Analysis (UAA) The attainment test is a monitor based test
Future year design values should also be examined in unmonitored areas
Unmonitored Area Analysis (UAA) is recommended Uses interpolated ambient design values and model output
Interpolated spatial fields (design values) are adjusted up or down based on modeled concentration gradients
Similar tests for ozone and PM2.5 UAA not designed to look for unmonitored PM micro-
scale hot-spot issues 12 km resolution should be sufficient for annual NAAQS Finer resolution may be needed to address 24-hr. NAAQS
UAA is a supplemental analysis If a problem area is identified, guidance recommends
implementing emissions controls or placing new monitor(s) in the area
Local Area Analysis (LAA)
Analysis to improve the accuracy of modeled emissions changes of local primary PM2.5 Local primary PM2.5 gradients cannot be accurately
modeled with a relatively coarse grid model LAA provides a more accurate assessment of the
change in air quality at monitors, due to changes in local primary emissions
Local area analysis can use either dispersion model or fine grid Eulerian model (1km?)
Local Area Analysis Analysis is applied by quarter For dispersion modeling analysis:
Identify local sources Quantify local source contribution at monitor Run dispersion model Use relative change in concentration to adjust
future year annual or 24-hour design values
Summary All nonattainment areas must submit an attainment
demonstration which includes future year modeling All O3/PM2.5/RH modeled attainment tests use model
estimates in a “relative” sense. Local primary PM2.5 sources are addressed as part of the
“unmonitored area analysis” and “local area analysis” UAA is intended to examine PM2.5 gradients in unmonitored
areas at 12km or finer resolution LAA is intended to examine local PM2.5 contributions to
existing FRM monitors
Appendix
Select Language from: “Guidance on the use of Models and Other Analyses for Demonstrating Attainment of Air Quality Goals for Ozone, PM2.5, and Regional Haze”.
Unmonitored Area Analysis: Guidance Language(sections 3.4, 3.4.3, and 5.3)
Modeling Guidance section 3.4.3 “It should be stressed that due to the lack of measured data, the examination of
ozone and PM2.5 concentrations as part of the unmonitored area analysis is more uncertain than the monitor based attainment test. As a result, the unmonitored area analysis should be treated as a separate test from the monitor based attainment test. The results from the unmonitored area analysis should, at a minimum, be included as a supplemental analysis. While it is expected that additional emissions controls are needed to eliminate predicted violations of the monitor based test, the same requirements may not be appropriate in unmonitored areas.”
“It is recommended that predicted violations of the unmonitored area analysis are carefully scrutinized to determine whether they are likely to exist in the ambient air or whether they may be caused by an error or uncertainty in the modeling system. At a minimum, it may be appropriate to commit to additional deployment of ambient monitors in areas where the unmonitored area analysis predicts future violations [footnote: It would also be appropriate to commit to additional emissions controls in lieu of additional monitoring in unmonitored areas]. This monitoring would allow a better assessment in the future of whether the NAAQS is being met at currently unmonitored locations.”
Unmonitored Area Analysis: Guidance Language
Additional language (section 5.3) “High primary PM concentrations can occur at (or near) existing monitors or in
unmonitored areas. The modeled attainment test is primarily a monitor based test. As such, the focus of the attainment test is whether attainment can be reached at existing monitors. To address the issue of PM2.5 concentrations in unmonitored areas, we have recommended an “unmonitored area analysis” (see section 3.4). The unmonitored area analysis is intended to be the primary means for identifying high PM2.5 concentrations outside of traditionally monitored locations. The spatial resolution of the modeling that is the underlying basis of the unmonitored area analysis will determine how well it addresses primary PM hotspot issues. The finer the resolution of the grid model, the more likely that primary PM hotspots will be recognized. Based on the monitoring guidance, we believe that an unmonitored area analysis conducted at 12km or finer resolution is sufficient to address unmonitored PM2.5 for the annual NAAQS. Conducting the unmonitored analysis at 4km or finer resolution will provide an even more detailed analysis of the spatial gradients of primary PM2.5, especially when evaluating violations of the 24-hr. NAAQS.”
Local Area Analysis: Guidance Language(sections 5.3 and 5.3.1) Modeling Guidance section 5.3.1
“…., if a designated nonattainment area contains a few (as opposed to many which are spread out) concentrated sources of primary particulate matter, we would expect there to be some substantial spatial gradients in the primary portion of the organic carbon component and in the inorganic particulate matter (OPP) and elemental carbon (EC) components of ambient PM2.5 (these are often called “hotspots”). Substantial gradients are most likely to be a potential problem in addressing whether a proposed control strategy is sufficient to attain the 24-hour NAAQS for PM2.5.”
“It may be necessary to evaluate the impact of local primary PM sources for contributions to both the 24-hour and annual NAAQS. As stated earlier, it may not be appropriate to compare population oriented FRM sites that are dominated by point sources, to the annual NAAQS. But there are numerous cases where the impact from local sources is not dominant, but a sizable contributor to total PM2.5 (~10-30% of total
annual average PM2.5). In these cases, a more refined analysis of the contribution of local
primary PM2.5 sources to PM2.5 at the monitor(s) will help explain the causes of
nonattainment at the monitor and may lead to the more efficient ways to attain the standard by controlling emissions from local sources.”
