SBA Claim: The vast majority of PM 2.5 from RICE travels less than 300m. Therefore, EPA should exempt rural engines from regulation and substantially reduce th e benefits estimates. Justification for this claim includes a citation to the Zhu et al (2002) ar ticle examining ultrafine particles near roadways.

• There is no data to suggest that a majority of stationary diesel RICE are rural. The available evidence shows that these engines are located in both rural and urban locations. The benefits estimates simulate a representative mixture of rural and urban emission locations across the country, including ground-level emissions and state-of-the science models for photochemistry and transport (U.S. EPA, 2006a). Even engines located in primarily rural areas would be upwind of more highly populated areas.

• EPA has extensively modeled PM 2.5 transport on similar on-road and non-road diesel engines and similar low-level sources for prior mobile source rulemakings, which all show that PM 2.5 emitted at ground-level can travel significant distances away from the source (U.S. EPA, 1999; U.S. EPA, 2000; U.S. EPA, 2004; U.S. EPA, 2008e ; U.S. EPA, 2010c). In addition, independent publications have concluded that the impacts of ground-level mobile source emissions extend for hundreds of miles (Greco et al., 2007).

• The recently finalized Integrat ed Science Assessment for Partic ulate Matter (U.S. EPA, 2009c), which is the compendium of known research regarding the science of PM, concludes that fine particles can travel hundreds to thousands of kilometers away from the emission source, whereas ultrafine and coarse particles travel less th an 10km away from a source (Table 3-1, U.S. EPA, 2009c). Also, shown in Wilson and Suh (1997).

• Most ultrafine particles accumula te to larger fine particles within minutes (U.S. EPA, 2009c; Kittelson, 1998; Zhu et al, 2002; Zhu et al, 2004; Barone and Zhu, 2008). Thus, ultrafines lose their identity as individual particles bu t still remain in the atmosphere as PM 2.5 (Kittelson, 1998). Ultrafine particles generally represent only about 10% of PM 2.5 mass (Mauderly and Chow, 2007; Morawska, 1998; Kittelson, 1998). Most diesel PM by mass is between 0.1 to 1 microns rather than ultrafine (below about 0.1 microns) (Kittels on, 1998). The benefits analysis is based on PM 2.5 mass; as a result, conclusions about potential benefits of reductions in PM 2.5 from RICE drawn from studies of ultrafine particles are not relevant.

• Although some near-roadway studies show a steep gradient of concentrations for some pollutants away from the source, much of the drop in concentration is due to the dispersion, not deposition, of diesel pollutants (U.S. EPA, 2002; Horvath, 1988). In other words, concentrations fall as particles disperse across distances, which supports transp ort to a broader region as the explanation rather than deposition within a limited distance from the source. Many near roadway studies show either no significant pollution gradient for PM 2.5 (Roorda-Knape et al, 1998; Zhu et al, 2004; Zhu et al, 2006) or a significantly less steep gradient for PM 2.5 (Tiitta et al, 2002; HEI, 2010). Several studies identify e vaporation, condensati on, coagulation, and dispersion (dilution) as the primary mechanisms for the change in particle number concentrations and size distribut ions near roadways (Zhang and Wexler, 2004; Zhang et al, 2004; Zhang et al, 2005; Jacobson et al., 2005).

• PM 2.5 deposition rates are extremely slow because gravitational settling is overwhelmed by buoyancy and other resistive forces. A recent repo rt from the Health Effects Institute on trafficrelated air pollution does not prov ide any evidence that elevated PM 2.5 concentrations disappear after 300 meters (HEI, 2010).• The benefits estimates are based on PM 2.5 , which can have adverse he alth effects on people living far away from emission sources at very lo w concentrations (Pope et al, 2002; Laden et al, 2006; Krewski et al, 2009).

• The primary purpose of this rule is to control HAP emissions. The main HAPs from RICE are gaseous (i.e., formaldehyde, acetaldehyde, PAHs, and acrolein). EPA modeling (U.S. EPA, 2010b) shows that these pollutants can travel hundreds of kilometers away from the source.

• We have already incorporated language suggested by DOE to address uncertainty in the PM cobenefits of the rule regarding the distance that PM 2.5 travels from these engines because they have not been studied specifically.

Studies sent to EPA for consideration:

Zhu et al (2002)

• Zhu et al (2002) primarily examined ultrafine particles, and only measured PM 2.5 indirectly via light scattering, a method that EPA does not allow for regulatory measurement. Thus, the authors state that the PM estimates are only useful as indicators of general trends.

• Zhu et al (2002) did not study deposition, but rather ambient concentrations of ultrafine particles. Neither the authors nor later mathematical modeling of the study domain suggest that deposition is a significant contri butor to particle number gradients.

• PM showed the shallowest gradient of all pollutants studied.

• There are 3 main reasons for any gradient of ultrafine particles (in order of importance): formation of larger fine particles, dispersion, depo sition through precipitation (U.S. EPA, 2009c).

Roorda-Knape et al (1998)

• The authors concluded that no clear near roadway gradient for PM 2.5 was found.

Mauderly and Chow (2007)

• Less than 10% of the PM 2.5 mass is ultrafine.

• The benefits analysis is based on PM 2.5 mass, not the number of particles. Reducing diesel PM emissions reduces ambient PM 2.5 mass concentrations.

Von Klot et al (2009)

• Used a land use regression model to estimate air quality. Photochemical dispersion models, such as those used by EPA, are vastly superior models for estimating pollutant concentrations across large geographic areas.

Language we have added to this RIA to address their concerns (excerpts):

“The underlying emissions modeling and air quality modeling account for the current distribution of emissions sources, including both urban and rural sources. In addition, the air quality modeling included 14 vertical layers to simulate the differences between ground-level emissions and higher stack emissions (U.S. EPA, 2006a ). The distance that particles tr avel primarily depends on the sizeof the particle and meteorological conditions, such as wind speed and precipitation. Fine particles can have an atmospheric half-life of days to weeks an d travel hundreds to thousands of kilometers, whereas ultrafine and coarse particles travel less than ten k ilometers (U.S. EPA, 2009c). Because we have not undertaken a study specific to emissions at ground le vel from RICE, with regard to transport issues and
to size fraction of PM 2.5 emissions (e.g., ultrafines and near ultrafines), there is uncertainty as to how far such emissions will travel and thus with regard to po pulations affected. Eviden ce from recent air quality modeling for mobile source rules wi th similar engines (U.S. EPA, 1999; U.S. EPA, 2000; U.S. EPA, 2004; U.S. EPA, 2008e; U.S. EPA, 2010c) shows that some fine particles can travel long distances in the atmosphere, but the proportion of su ch emissions from RICE that travel more than short distances is not yet definitively known.”

“The distance that these HAPs travel away from the emission source depends on several factors. HAPs such as formaldehyde, acetaldehyde, PAHs, and acrolein are emitted as gases. Regional photochemical model simulations have shown that gaseous HAPs like formaldehyde and acetaldehyde can be transported hundreds of kilometers from thei r emissions source in distinct plumes (U.S. EPA, 2010b). Further, these emissions can contribute to re gional airmasses with elevated concentrations of gaseous HAPs. These polluted airmasses can be transported thousands of kilometers and affect
locations well distant from the or iginal emissions source. Some gaseous HAPs with higher molecular weight, such as toluene, can transform into particles in the atmosphere. For HAPs emitted as particles, such as metals, the travel distance primarily depends on the size of the particle and meteorological conditions, such as wind speed and precipitation. Fine particles can have an atmospheric half-life of days to weeks and travel hundreds to thousands of kilometers, whereas ultrafine and coarse particles
travel less than ten kilomete rs (U.S. EPA, 2009c).”

References

Barone, Theresa and Yifang Zhu. 2008. The morpho logy of ultrafine particles on and near major freeways. Atmospheric Environment Volume 42, Issue 28, September, Pages 6749-6758.

Greco, SL, Wilson AM, Spengler JD, Levy JI. 2007. Fa ctors Influencing Mobile Source Particulate Matter Emissions-to-Exposure relationships in the Boston Urban Area Atmos Environ 41: 1011-1025.

HEI Panel on the Health Effects of Traffic-Related Air Pollution. 2010. Traffic-Related Air Pollution: A Critical Review of the Literature on Emissions, Ex posure, and Health Effects. HEI Special Report 17. Health Effects Institute, Boston, MA.

Horvath, H; Kreiner, I; Norek, C; et al. 1988. Diesel emissions in Vienna. Atmos Environ 22:1255-1269.

Jacobson, M. Z., D. B. Kittelson, and W. F. Watts. 2005. Enhanced Coagulation Due to Evaporation and Its Effect on Nanoparticle Evolution, Environ. Sci. Technol. 39, 9486.Kittelson, DB. 1998. Engines and nanopartic les: a review. J Aerosol Sci 29:575-588.

Krewski D, Jerrett M, Burnett R T, Ma R, Hughes E, et al. 2009 Extende d follow-up and spatial analysis of the American Cancer Society study linking particulate air pollution and mortality. HEI Research Report, 140, Health Effect s Institute, Boston, MA.

Laden, F., J. Schwartz, F.E. Speizer, and D.W. Dock ery. 2006. Reduction in Fine Particulate Air Pollution and Mortality. American Journal of Respiratory and Critical Care Medici ne 173:667-672. Estimating the Public Health Benefits of Proposed Air Po llution Regulations. Washington, DC: The National Academies Press.

Mauderly, J.L. and J.C. Chow. 2008.). Health Effects of Organic Aerosols. Inha l. Toxicol., 20(3):257-288.

Morawska, L., Bofinger, N. D., Kocis, L., a nd Nwankwoala, A. (1998). Submicrometer and Supermicrometer Particles from Diesel Vehicle Emissions, Environ. Sci. Technol. 32:2033–2042.

Pope, C.A., III, R.T. Burnett, M.J. Thun, E.E. Calle , D. Krewski, K. Ito, and G.D. Thurston. 2002. Lung Cancer, Cardiopulmonary Mortality, and Long-term Exposure to Fine Particulate Air Pollution. Journal of the American Medical Association 287:1132-1141.

Roorda-Knape MC, Janssen NAH, de Hartog JJ, van Vliet PHN, Harssema H, Brunekreef B. Air pollution from traffic in city districts near majo r motorways. Atmos Environ. 1998;32(11):1921–1930.

U.S. Environmental Protection Agency (U.S. EPA). 1999. Regulatory Impact Analysis - Control of Air Pollution from New Motor Vehicles: Tier 2 Motor Vehicle Emissions Standards and Gasoline Sulfur Control Requirements. EPA420-R-99-023, December 1999. http://www.epa.gov/tier2/frm/ria/r990 23.pdf. Accessed February 9, 2010.

U.S. Environmental Protection Agency (U.S. EPA). 20 00. Regulatory Impact Analysis: Heavy-Duty Engine and Vehicle Standards and Highway Diesel Fuel Sulfur Control Requirements. Prepared by Office of Air and Radiation. EPA420-R-00-026, December 2000. Available at http://www.epa.gov/otaq/highway-diesel/regs/200 7-heavy-duty-highway.htm. Accessed February 9, 2010.

U.S. Environmental Protection Agency (U.S. EPA). 20 02. Health Assessment Document for Diesel Engine Exhaust. U.S. Environmental Protection Agency, Office of Research and Development, National Center for Environmental Assessment, Washi ngton Office, Washington, DC, EPA/600/8-90/057F.

U.S. Environmental Protection Agency (U.S. EPA). 2004. Final Regulatory Analys is: Control of Emissions from Nonroad Diesel Engines. EPA420-R-04-007, May 2004. Prepared by Office of Air and Radiation. http://www.epa.gov/ nonroad-diesel/2004fr/420r04007.pdf. Accessed February 9, 2010.

U.S. Environmental Protection Agency (U.S. EPA). 2006a. Technical Support Do cument for the Proposed PM NAAQS Rule: Response Surface Modeling. Office of Air Quality Planning and Standards, Research Triangle Park, NC. February. Available on the Internet at <http://www.epa.gov/scram001/report s/pmnaaqs_tsd_rsm_all_021606.pdf>.U.S. Environmental Protection Agen cy. 2008e. Regulatory Impact Analys is: Control of Emissions of Air Pollution from Locomotive Engines and Marine Compression Ignition Engines Less than 30 Liters Per Cylinder. Prepared by Office of Air an d Radiation. EPA420-R-08-001a, May 2008. http://www.epa.gov/oms/regs/nonroad/420r 08001a.pdf. Accessed February 9, 2010.

U.S. Environmental Protection Agency (U.S. EPA). 2009c. Integrated Science Assessment for Particulate Matter (Final Report). EPA-600-R-08-139F. Nation al Center for Environmental Assessment – RTP Division. December. Availa ble on the Internet at <http://cfpub.epa.gov/ncea/cf m/recordisplay.cfm?deid=216546>.

U.S. Environmental Protection Agency (U.S. EP A). 2010b. Air Quality Mo deling Technical Support Document: Changes to the Renewable Fuel Standard Program, Office of Air Quality Planning and Standards, EPA 454/R-10-001. February . Available on the Internet at <http://www.epa.gov/OMS/renewablefuels/454r10001.pdf>.

U.S. Environmental Protection Ag ency (U.S. EPA). 2010c. Renewabl e Fuel Standard Program (RFS2) Regulatory Impact Analysis. EPA-420-R-10-006, Febr uary 2010. Prepared by Office of Air and Radiation. http://www.epa.go v/OMS/renewablefuels/420r10006.pdf. Accessed February 9, 2010.

von Klot, Stephanie; Gryparis, Alexandros; Tonne, Cath ryn; Yanosky, Jeffrey; Coull, Brent A.; Goldberg, Robert J.; Lessard, Darleen; Melly, Steven J.; Suh, Helen H.; Schwar tz, Joel. 2009. Elemental Carbon Exposure at Residence and Survi val After Acute Myocardial Infarction. Epidemiology: July. Vol 20, Issue 4, pp 547-554.

Wilson WE; Suh HH. 1997. Fine part icles and coarse particles: concen tration relationships relevant to epidemiologic studies. J Air Waste Manag Assoc, 47: 1238-1249.

Zhang, K. Max and Anthony S. Wexler. 2004. Evolut ion of particle number distribution near roadways— Part I: analysis of aerosol dynamics and its implications for engine emission measurement. Atmospheric Environment Volume 38, Issue 38, December, Pages 6643-6653.

Zhang, K. Max, Anthony S. We xler, Yi Fang Zhu, William C. Hinds , and Constantinos Sioutas. 2004. Evolution of particle number distribution near ro adways. Part II: the ‘Road-to-Ambient’ process. Atmospheric Environment, Volume 38, Issue 38, December, Pages 6655-6665.

Zhang, K. Max, Anthony S. Wexler, Debbie A. Niem eier, Yi Fang Zhu, William C. Hinds, Constantinos Sioutas. 2005. Evolution of particle number distribut ion near roadways. Part III: Traffic analysis and on-road size resolved particulate emission factors, Atmospheric En vironment. Volume 39, Issue 22, July, Pages 4155-4166.

Zhu, Y. F.; Hinds, W. C.; Kim, S.; Sioutas, C. 2002. Co ncentration and size distribution of ultrafine particles near a major highway. J. Air Waste Manage. Assoc. 52, 1032

− 1042.

Zhu, Y. F.; Hinds, W. C.; Shen, S.; Sioutas, C. 2004. Seasonal trends of concentration and size distribution of ultrafine particles near major highways in Los Angeles. Aerosol Sci. Technol. 38, 5-13.Zhu, Y.; Thomas Kuhn, Paul Mayo, and William C. Hinds. 2006. Comparison of Daytime and Nighttime Concentration Profiles and Size Distributions of Ul trafine Particles near a Major Highway. Environ. Sci. Technol., 40 (8), pp 2531–2536.