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Federal Register / Vol. 62, No. 28 / Tuesday, February 11, 1997 / Proposed Rules6369increased bronchitis in children. Inaddition to the direct effects of NO X, thechemical transformation products ofNO X also contribute to adverse healthand environmental impacts. Thesesecondary impacts of NO X includeground-level ozone, nitrate particulatematter, acid deposition, eutrophication(plant overgrowth) of coastal waters,and transformation of other pollutantsinto more dangerous chemical forms.Ozone is a highly reactive chemicalcompound that can affect bothbiological tissues and man-madematerials. Ozone exposure causes arange of human pulmonary andrespiratory health effects. While ozone’seffects on the pulmonary function ofsensitive individuals or populations(e.g., asthmatics) are of primary concern,evidence indicates that high ambientlevels of ozone can cause respiratorysymptoms in healthy adults andchildren as well. For example, exposureto ozone for several hours at moderateconcentrations, especially duringoutdoor work and exercise, has beenfound to decrease lung function,increase airway inflammation, increasesensitivity to other irritants, and impairlung defenses against infections inotherwise healthy adults and children.Other symptoms include chest pain,coughing, and shortness of breath.In recent years, significant effortshave been made on both a national andstate level to reduce air qualityproblems associated with ground-levelozone, with a focus on its mainprecursors, oxides of nitrogen (NO X)and volatile organic compounds(VOCs). 5 The precursors to ozone andozone itself are transported longdistances under some commonlyoccurring meteorological conditions.Specifically, concentrations of ozoneand its precursors in a region and thetransport of ozone and precursorpollutants into, out of, and within aregion are very significant factors in theaccumulation of ozone in any givenarea. Regional-scale transport may occurwithin a state or across one or morestate boundaries. Local source NO X andVOC controls are key parts of the overallattainment strategy for nonattainmentareas. However, the ability of an area toachieve ozone attainment and therebyreduce ozone-related health andenvironmental effects is often heavilyinfluenced by the ozone and precursoremission levels of upwind areas. Thus,for many of these areas, EPA believesthat attainment of the ozone NAAQSwill require control programs muchbroader than strictly locally focusedcontrols to take into account the effectof emissions and ozone far beyond theboundaries of any individualnonattainment area.EPA therefore believes that effectiveozone control requires an integratedstrategy that combines cost-effectivereductions in emissions from bothmobile and stationary sources. EPA’scurrent initiatives, including thenational locomotive emissionsstandards proposed in this action, arecomponents of the Agency’s integratedozone reduction strategy.In addition to ozone, airborneparticulate matter (PM) has been a majorair quality concern in many regions.Ozone and PM have both been linked toa range of serious respiratory healthproblems and a variety of adverseenvironmental effects. As waspreviously discussed, ozone causesharmful respiratory effects includingchest pain, coughing, and shortness ofbreath. Similarly, PM exposure isassociated with health effects includingshortness of breath, aggravation ofexisting respiratory disease, cancer, andpremature death.Beyond their effects on human health,other negative environmental effects arealso associated with ozone, NO X, andPM. Ozone has been shown to injureplants and materials; NO X contributes tothe secondary formation of PM(nitrates), acid deposition, and theovergrowth of algae in coastal estuaries.PM can damage materials and impairvisibility. These effects are extensivelydiscussed in EPA’s ‘‘air quality criteria’’documents for NO X, ozone, and PM. 6 7 8EPA recently proposed revisions to thenational ambient air quality standards(NAAQS) for ozone and PM. 9IV. Emissions from Present LocomotivesA. National InventoriesContributions by locomotives to thenational emissions inventories forvolatile organic compounds (VOC),carbon monoxide (CO), oxides ofnitrogen (NO X) and particulate matter(as PM–10) are summarized in Table IV–1. The values shown in Table IV–1 arethe total national inventories from allsources, from mobile sources, and fromlocomotives for 1990. The railroadinventories, expressed as the percentagecontributions by commercial railroadsto the total national inventories and tothe transportation sources inventories,are shown in Table IV–2. The Agencyrecognizes that not all of thelocomotives in service are owned andoperated by commercial (includingpublic) railroads. The locomotives notoperated by the commercial railroadsare generally used to transportequipment and materials within anindustrial facility. However, in light ofthe small percentage of in-uselocomotives that are not operated bycommercial railroads, EPA believes thatthe emissions from these locomotivesare an extremely small percentage of thetotal emissions from all locomotives inservice. Thus, for the purposes of thisdiscussion it is assumed that locomotiveand railroad emission inventories areequivalent.TABLE IV–1 1 .—1990 NATIONAL EMISSION INVENTORIES: ALL SOURCES, MOBILE SOURCES, AND LOCOMOTIVES[millions of metric tons]EmissionTotal from allsourcesMobilesourcesLocomotivesNO X .............................................................................................................................................. 20.90 9.37 0.98PM–10 .......................................................................................................................................... 39.31 0.66 .024VOC .............................................................................................................................................. 21.41 8.14 .0385 VOCs consist mostly of hydrocarbons (HC).6 Air Quality Criteria Document for Oxides ofNitrogen, EPA–600/8–91/049aF–cF, August 1993(NTIS #: PB92–17–6361/REB,– 6379/REB, –6387/REB).7 Air Quality Criteria Document for Ozone andRelated Photochemical Oxidants (External ReviewDraft), EPA/600/P–93/004aF–cF, 1996.8 Air Quality Criteria for Particulate Matter(External Review Draft), EPA–600/AP–95/001a–a,April 1995.9 61 FR 65638 (PM) and 61 FR 65716 (ozone),December 13, 1996.