EPA is proposing - Petroleum Equipment Institute

We note that the aggregate nationwide emission inventory impacts presented herewill likely lead to health impacts throughout the U.S. due to changes in future-yearambient air quality. However, emissions changes alone are not a good indication of localor regional air quality and health impacts, as there may be highly localized impacts suchas increased emissions from ethanol plants and evaporative emissions from cars, anddecreased emissions from gasoline refineries. In addition, the atmospheric chemistryrelated to ambient concentrations of PM2.5, ozone and air toxics is very complex, andmaking predictions based solely on emissions changes is extremely difficult. Full-scalephotochemical modeling is necessary to provide the needed spatial and temporal detail tomore completely and accurately estimate the changes in ambient levels of thesepollutants. As discussed in Section VII.D, timing and resource constraints precludedEPA from conducting a full-scale photochemical air quality modeling analysis in time forthe NPRM. For the final rule, however, a national-scale air quality modeling analysiswill be performed to analyze the impacts of the proposed standards on PM2.5, ozone, andselected air toxics (i.e., benzene, formaldehyde, acetaldehyde, ethanol, acrolein and 1,3­butadiene). As described in Section VII.D.2, EPA intends to use a 2005-basedCommunity Multi-scale Air Quality (CMAQ) modeling platform as the tool for the airquality modeling. The CMAQ modeling system is a comprehensive three-dimensionalgrid-based Eulerian air quality model designed to estimate the formation and fate ofoxidant precursors, primary and secondary PM concentrations and deposition, and airtoxics, over regional and urban spatial scales (e.g., over the contiguous U.S.).The lack of air quality modeling data also precluded EPA from conducting itsstandard analysis of human health impacts, where CMAQ output data are used as inputsto the Environmental Benefits Mapping and Analysis Program (BenMAP). Section IX.Dof this preamble describes the human health impacts that will be quantified andmonetized for the final rule, as well as the unquantified impacts that will be qualitativelydescribed.4. WaterAs the production of biofuels increases to meet the requirements of this proposedrule, there may be adverse impacts on both water quality and quantity. Increasedproduction of biofuels may lead to increased application of fertilizer and pesticides andincreased soil erosion, which could impact water quality. Since ethanol production useslarge quantities of water, the supply of water could also be significantly impacted in somelocations.EPA focused the water quality analysis for this proposal on the impacts of cornproduced for ethanol for several reasons. Corn has the highest fertilizer and pesticide useper acre and accounts for the largest share of nitrogen fertilizer use among all crops.Furthermore, corn-based ethanol is expected to be a large component of the biofuels mix.Fertilizer nutrients that are not used by the crops are available to runoff to surfacewater or leach into groundwater. Nutrient enrichment due to human activities is one of39