A. INTRODUCTION AND METHODOLOGY

Chapter 10: Air Quality A. INTRODUCTION AND METHODOLOGY The different alternatives being evaluated as part of the Manhattan East Side Transit Alternatives Study have the potential to result in air quality impacts that could be caused by the emissions from increased congestion or the diversion of motor vehicles to alternative routes, or by the reduction in auto-related traffic as drivers shift from automobiles to mass transit. The potential localized impacts and regional benefits from the project alternatives on air quality are evaluated in this chapter. POLLUTANTS FOR ANALYSIS In New York City, ambient concentrations of carbon monoxide, ozone, and lead are predominantly influenced by mobile source emissions; emissions of nitrogen oxides come from both mobile and stationary sources; and emissions of respirable particulate matter and sulfur dioxide are associated mainly with stationary sources. CARBON MONOXIDE Carbon monoxide (CO), a colorless and odorless gas, is produced in the urban environment primarily by the incomplete combustion of gasoline and other fossil fuels. In New York City, approximately 80 to 90 percent of CO emissions are from motor vehicles. CO concentrations can vary greatly over relatively short distances. Elevated concentrations are usually limited to locations near crowded intersections, along heavily traveled and congested roadways or at parking lots or garages. Consequently, CO concentrations must be predicted on a localized or microscale basis. The Build alternatives would produce diversions of traffic that may result in localized increases in CO levels. Therefore, an analysis of the impact from the Build alternatives traffic diversions on CO levels at critical intersections in the project study area was performed. In addition, the project alternatives would reduce vehicular travel in the region, as measured in annual vehicle miles traveled. Therefore, a regional analysis was performed for CO, computing total expected quantities of CO emitted in a year, to determine potential benefits resulting from the general changes in vehicular activity on overall background levels of this pollutant. NITROGEN OXIDES AND OZONE Nitrogen oxides (NO x) are of principal concern because of their role with volatile organic com- pounds (VOCs) as precursors in the formation of ozone. There is a standard for average annual nitrogen dioxide (NO 2) concentrations, which is normally examined only for fossil fuel energy sources. Ozone is formed through a series of reactions that take place in the atmosphere in the presence of sunlight. Because the reactions are slow and occur as the pollutants are diffusing downwind, elevated ozone levels are often found many miles from sources of the precursor 10-1

Manhattan East Side Transit Alternatives MIS/DEIS pollutants. The effects of NO and VOC emissions from mobile sources are therefore generally x examined on a regional basis. The change in regional mobile source emissions of these pollutants is related to the total number of vehicle trips and vehicle miles of travel throughout the New York metropolitan area. The proposed Build alternatives would potentially result in changes to the regional vehicular travel patterns in the study area zones. Therefore, the change in regional NO and VOC emissions were analyzed for the Build alternatives. x LEAD Lead emissions are principally associated with industrial sources and motor vehicles that use gasoline containing lead additives. Most U.S. vehicles produced since 1975, and all produced after 1980, are designed to use unleaded fuel. As these newer vehicles have replaced the older ones, motor-vehicle-related lead emissions have decreased. As a result, ambient concentrations of lead have declined significantly. Nationally, the average measured atmospheric lead level in 1985 was only about one-quarter the level in 1975. In 1985, the U.S. Environmental Protection Agency (EPA) announced new rules drastically reducing the amount of lead permitted in leaded gasoline. The maximum allowable lead level in leaded gasoline was reduced from the previous limit of 1.1 to 0.5 grams per gallon effective July 1, 1985, and to 0.1 grams per gallon effective January 1, 1986. Monitoring results indicate that this action has been effective in significantly reducing atmospheric lead levels. Even at locations in the New York City area where traffic volumes are very high, atmospheric lead concentrations are far below the national standard of 1.5 micrograms per cubic meter (3-month average). No significant sources of lead are associated with the proposed Build alternatives, and therefore, an analysis was not warranted. RESPIRABLE PARTICULATES PM 10 Particulate matter is emitted into the atmosphere from a variety of sources: industrial facilities, power plants, oil burners, construction activity, and so forth. Gasoline-powered vehicles do not produce any appreciable quantities of particulate emissions. Diesel-powered vehicles, especially heavy trucks and buses, do emit particulates; particulate concentrations may therefore be locally elevated near roadways with high volumes of heavy diesel-powered vehicles. While the proposed Build alternatives would not result in a significant increase in diesel truck trips, new bus service and route modifications are proposed. Potential effects on respirable particulate levels are discussed below. Particulates less than 10 µm in diameter (PM 10) have become of primary concern because they are respirable. In addition to PM 10, the U.S. Environmental Protection Agency (EPA) has deter- mined that elevated airborne levels of particulate matter less than 2.5 microns (PM 2.5), show consistent and coherent associations with serious health effects. Air quality monitoring indicates that, in the past, respirable particulate levels in New York City have exceeded the applicable national ambient air quality standards at only one monitored location, along Madison Avenue in midtown Manhattan. Manhattan continues to be a non-attainment area with respect to PM. 10 The proposed New York Bus Lanes of the TSM Alternative would result in increased bus speeds on First and Second Avenues in the study area. Particulate emissions would be reduced, since emissions decrease with higher vehicle travel speeds. The new bus routes and route modifications in some study area zones (and particularly the Lower East Side) under all Build 10-2

Chapter 10: Air Quality alternatives would not significantly affect respirable particulate levels, since the proposed changes are reallocations and overall regional emissions would not change. As mentioned earlier, recent monitoring data demonstrate only one monitoring location in Manhattan where localized particulate levels are high. At this location, on Madison Avenue in Midtown, concentrations have exceeded standards in the past due to extremely high bus volumes. The total bus volumes along routes affected by the Build alternatives are minor, and the overall effect on particulate levels in the study area zone would be localized and insignificant. Therefore, the proposed Build alternatives would not result in any significant or adverse impacts on respirable particulate levels in the study area and no detailed analysis of particulates is required. SULFUR DIOXIDE Sulfur dioxide (SO 2) emissions are primarily associated with the combustion of sulfur-containing fuels: oil and coal. No significant quantities are emitted from mobile sources. Monitored SO 2 concentrations in Manhattan are below the national standards. No significant sources of SO 2 are associated with the Build alternatives, and therefore, an analysis was not warranted. CONCLUSIONS The areas of potentially significant air quality impacts from the proposed Build alternatives that require an analysis are the following:! Effects of the proposed Build alternatives on CO concentrations due to potential diversions in traffic; and! Potential effects on regional emissions of CO, VOCs, and NO due to potential changes in x vehicular travel patterns in the study area zones resulting from the proposed Build alternatives. AIR QUALITY STANDARDS NATIONAL AND STATE AIR QUALITY STANDARDS As required by the Clean Air Act, primary and secondary National Ambient Air Quality Standards (NAAQS) have been established for six major air pollutants: carbon monoxide, nitrogen dioxide, ozone, respirable particulate matter, sulfur dioxide, and lead. (Hydrocarbon standards have been rescinded because these pollutants are primarily of concern only in their role as ozone precursors.) EPA has recently promulgated additional respirable particulate matter standards. In addition to retaining PM standards, EPA has adopted 24-hour and annual standards for 10 respirable particulate matter with an aerodynamic equivalent diameter less than 2.5 µm (PM 2.5), which became effective September 16, 1997. As recognized by EPA, the adoption of the PM 2.5 standard is intended to provide increased protection of public health from fossil fuel combustion. At this time, EPA is only requiring states to implement monitoring programs for PM 2.5. It will likely be at least 5 years before any attainment/non-attainment designations are made and a few more years before any implementation plans respecting PM 2.5 are required. Table 10-1 shows the standards for these pollutants. These standards have also been adopted as the ambient air quality standards for the State of New York. The primary standards protect the public health, and represent levels at which there are no known significant effects on human health. The 10-3

Manhattan East Side Transit Alternatives MIS/DEIS secondary standards are intended to protect the nation's welfare, and account for air pollutant effects on soil, water, visibility, materials, vegetation, and other aspects of the environment. For CO, NO, ozone, and respirable particulates, the primary and secondary standards are the same. 2 Table 10-1 National and New York State Ambient Air Quality Standards Primary Secondary Micrograms Micrograms Pollutant PPM Per Cubic Meter PPM Per Cubic Meter Carbon Monoxide Maximum 8-Hour Concentration1 9 9 Maximum 1-Hour Concentration1 35 35 Lead Maximum Arithmetic Mean Averaged 1.5 Over 3 Consecutive Months Nitrogen Dioxide Annual Arithmetic Average 0.05 100 0.05 100 Ozone 2 1-Hour Maximum 0.12 235 0.12 235 8-Hour Maximum 0.08 157 0.08 157 Respirable Particulates (PM 10) Annual Geometric Mean 50 50 Maximum 24-Hour Concentration3 150 150 Respirable Particulates (PM 2.5) Annual Arithmetic Mean 15 15 Maximum 24-Hour Concentration4 65 65 Sulfur Dioxide Annual Arithmetic Mean 0.03 80 Maximum 24-Hour Concentration* 0.14 365 Maximum 3-Hour Concentration* 0.50 1,300 Notes: 1 Not to be exceeded more than once a year. 2 The ozone 1-hour standard applies only to areas that were designated nonattainment when the ozone 8-hour standard was adopted in July 1997. 3 Not to be exceeded by 99th percentile of 24-hour PM 10 concentrations in a year (averaged over 3 years). 4 Not to be exceeded by 98th percentile of 24-hour PM 2.5 concentrations in a year (averaged over 3 years). Sources: 40 CFR Part 50 National Primary and Secondary Ambient Air Quality Standards 40 CFR 50.12 National Primary and Secondary Standard for Lead, 43 CFR 46245. 10-4

Chapter 10: Air Quality STATE IMPLEMENTATION PLAN (SIP) The Clean Air Act requires each state to submit to EPA a SIP for attainment of NAAQS. The 1977 and 1990 amendments require comprehensive plan revisions for areas where one or more of the standards have yet to be attained. In the New York City metropolitan area, the standard for ozone continues to be exceeded. As part of the SIP, New York City is implementing measures to reduce levels of hydrocarbons and nitrogen oxides as part of its effort to attain the NAAQS ozone standard. All of New York City continues to be designated as moderate non-attainment for CO and Manhattan has recently been designated as a moderate non-attainment area for PM. 10 The New York State Department of Environmental Conservation (NYSDEC) has submitted the carbon monoxide SIP to EPA and is awaiting final approval. The SIP contains control programs and contingency measures necessary to reduce carbon monoxide emissions to meet the standard in New York City by the Clean Air Act Amendment (CAAA) attainment date of December 31, 1995. For ozone, the CAAA requires a series of SIP revisions. These revisions include air quality control measures for target years emission reductions of ozone precursor emissions (volatile organic compounds and nitrogen oxides) and for an ozone attainment demonstration by 2007. In June 1997, NYSDEC submitted an ozone SIP revision that addressed the status of these requirements. DE MINIMIS CRITERIA For all pollutants, causing the NAAQS to be exceeded generally constitutes a significant impact. In addition to the NAAQS, New York City has developed de minimis criteria to assess the significance of impacts on air quality that would result from proposed projects or actions. These set the minimum change in CO concentration that defines a significant environmental impact. Significant increases with respect to CO concentrations in New York City are defined as: (1) an increase of 0.5 parts per million (ppm) or more in the maximum 8-hour average CO concentration at a location where the predicted No Build Alternative 8-hour concentration is equal to or between 8 and 9 ppm, or 2) an increase of more than half the difference between baseline concentrations and the 8-hour standard, when No Build Alternative concentrations are below 8.0 ppm. CONFORMITY WITH NEW YORK STATE AIR QUALITY IMPLEMENTATION PLAN The 1990 CAAA requires all federally funded or approved transportation project in nonattainment areas to conform to the purpose of the SIP. These federal air quality requirements are promulgated in Criteria and Procedures for Determining Conformity to State or Federal Implementation Plans of Transportation Plans, Programs and Projects Funded or Approved Under Title 23 USC or the Federal Transit Act (40 CFR Parts 51 and 93). In order to demonstrate conformity, actions must not exacerbate or delay the achievement of attainment of standards in such areas. Therefore, the MESA project is required to conform to the purpose and specific requirements of the SIP, cause no new violations, no exacerbation of existing violations, and no delays in the achievement of the NAAQS or interim emissions reductions milestones. The MESA alternatives conformance with these requirements was evaluated, as described in this chapter. 10-5

Manhattan East Side Transit Alternatives MIS/DEIS In addition, as described in Chapter 1, the New York Metropolitan Transportation Council (NYMTC), in cooperation with local transportation agencies, is responsible for the development of a financially constrained Long Range Plan (LRP) and annual Transportation Improvement Program (TIP) for the New York Metropolitan Region. As part of its long range plan, NYMTC has developed a TIP, which addresses and coordinates specific transportation projects in the region in accordance with regional transportation goals. The MESA study is included in the TIP. All major transit and highway capacity investments must be subject to a Major Investment Study (MIS) before they can be incorporated into a region s transportation plans (LRP and TIP). This MIS is part of that process. METHODOLOGY FOR PREDICTING POLLUTANT CONCENTRATIONS FROM MOBILE SOURCES To compare estimated CO concentrations with the national and state ambient air quality standards for CO (which are based on 1- and 8-hour averages of CO concentrations), estimates of maximum concentrations for these same periods must be prepared. Since experience in New York City has been that violations of the 1-hour CO standard are extremely rare, the CO analysis for this study focuses on determining the maximum predicted 8-hour CO concentrations for the project alternatives. The prediction of motor-vehicle-generated CO concentrations in an urban environment characterized by meteorological phenomena, traffic conditions, and physical configurations is a challenging problem. Air pollutant dispersion models simulate mathematically how traffic, meteorology, and geometry combine to affect pollutant concentrations. The mathematical expressions and formulations that comprise the various models attempt to describe an extremely complex physical phenomenon as closely as possible. However, because all models contain simplifications and approximations of actual conditions and interactions, and because a worst-case condition is of most interest, most of these dispersion models are conservative and tend to overpredict pollutant concentrations, particularly under adverse meteorological conditions. The CO analysis for this project uses a modeling approach approved by EPA that has been widely used for evaluating air quality impacts of projects in New York City, New York State, and throughout the country, and has coupled this approach with a series of worst-case assumptions relating to meteorology, traffic, background concentration levels, etc. This combination results in a conservative estimate of expected CO concentrations and resulting air quality impacts caused by the project. DISPERSION MODELS FOR MICROSCALE ANALYSES At all sites selected for analysis, maximum 1- and 8-hour average CO concentrations were first determined using EPA's CAL3QHC model, version 2, (User's Guide to CAL3QHC, A Modeling Methodology for Predicting Pollutant Concentrations Near Roadway Intersections, Office of Air Quality, Planning Standards, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina). The CAL3QHC model is based on the CALINE-3 line source dispersion model with an additional algorithm for estimating vehicle queue lengths at signalized intersections. The CALINE-3 model is a Gaussian model, which assumes that the dispersion of pollutants downwind of a pollution source follows a Gaussian (or normal) distribution, and is used for predicting CO concentrations along roadway segments. The 10-6

Chapter 10: Air Quality pollution source is the emissions from motor vehicles operating under free-flow conditions. The refinement that CAL3QHC provides is the inclusion of the contribution of emissions from idling vehicles in the overall concentration. The queuing algorithm requires additional input for site-specific traffic parameters, such as signal timing, and performs delay calculations from the 1994 Highway Capacity Manual traffic forecasting model to predict the number of idling vehicles. The CAL3QHC model was recently modified to include saturation flow rate, vehicle arrival type, and signal actuation characteristics as input parameters. Peak 8-hour concentrations were determined by applying a persistence factor to the maximum 1-hour values. At locations where maximum predicted CO concentrations obtained using the CAL3QHC model exceed the applicable ambient air quality standard, a more refined model, the CAL3QHCR (CAL3QHCR User s Guide, Office of Air Quality, Planning Standards, U.S. Environmental Protection Agency, Research Triangle Park, September 1995) was utilized for determining maximum concentration. CAL3QHCR is an enhanced but separate version of CAL3QHC that allows for the incorporation of actual meteorological data into the modeling, instead of worstcase assumptions regarding meteorological parameters. CAL3QHCR processes hourly meteorological data along with inputted traffic data and CO emissions rates to more accurately estimate maximum potential CO levels. Under the Tier I simulation scenario, CAL3QHCR utilizes peak hour traffic data and corresponding CO emission rates with an extensive meteorological data base. The CAL3QHCR model also allows for varying traffic volumes of peak hour conditions (i.e., Tier II simulation scenario), which generally results in maximum predicted CO levels less than those calculated under Tier I (because traffic volumes during off-peak conditions are much less than corresponding peak hour volumes). For this study, where necessary, the Tier I modeling scenario with the CAL3QHCR model was employed. WORST-CASE METEOROLOGICAL CONDITIONS In general, the transport and concentration of pollutants from vehicular sources are influenced by three principal meteorological factors: wind direction, wind speed, and atmospheric stability, which accounts for the effects of dispersion or mixing in the atmosphere. Wind direction, which influences the accumulation of pollutants at a particular receptor location, was chosen to maximize pollutant concentrations at each of the prediction sites. In applying the CAL3QHC modeling, the wind angle was varied to determine the worst-case wind direction resulting in the maximum concentrations. Following the recommendations of EPA and the New York City Department of Environmental Protection (DEP) for the CAL3QHC model, CO computations were performed using a wind speed of 1 meter/second, and stability class D, representative of neutral conditions. A persistence factor of 0.77 for the 8-hour period was selected, a conservative assumption based on conditions for midtown Manhattan. The persistence factor takes account of the fact that over 8 hours, traffic parameters will fluctuate downward from the peak and meteorological conditions will change, as compared with the 1-hour values. A surface roughness of 3.21 meters was chosen, and, in addition, a 50E Fahrenheit ambient temperature was assumed for the emissions computations. At each receptor location, the wind angle that maximized the pollutant concentrations was used in the analysis regardless of frequency of occurrence. 10-7

Manhattan East Side Transit Alternatives MIS/DEIS For the refined analysis using the CAL3QHCR model, 5 years of meteorological data with surface data from La Guardia Airport (1991-1995) and concurrent upper air data from Atlantic City, New Jersey and Brookhaven, New York were used in the simulation program. VEHICLE EMISSIONS DATA To predict ambient concentrations of pollutants generated by vehicular traffic, emissions from vehicle exhaust systems must be estimated. Vehicular emissions were computed using the EPAdeveloped Mobile Source Emissions Model, MOBILE5B. Emission estimates were made for six classes of motor vehicles:! Light-duty, gasoline-powered automobiles;! Light-duty, gasoline-powered taxis new;! Light-duty, gasoline-powered taxis old police cars;! Light-duty, gasoline-powered trucks;! Heavy-duty, gasoline-powered trucks; and! Heavy-duty, diesel-powered trucks. No light-duty diesel-powered vehicles (automobiles and taxis), light-duty diesel-powered trucks, or motorcycles were assumed. In the case of motorcycles, the number of such vehicles on any street is generally small. In the case of diesel-powered vehicles, emissions from a comparable class of gasoline-powered vehicles were included. CO emissions from the gasoline-powered vehicles are higher than the comparable diesel-powered vehicle emissions, and thus yield conservative estimates of total composite CO emissions and concentrations. The emissions were developed with the MOBILE5B model and assumed an ambient temperature of 50E Fahrenheit. For the refined analysis, CO emission estimates were also based on an average temperature of 50E Fahrenheit. Oxygenated fuel credits emission estimates for oxygenated fuels were based on a gasoline blend with a 2.7 percent oxygen content were taken in the microscale modeling analyses for the months of January-April and October-December only. These are the DEC-approved credits. Emission estimates were based on implementation of the New York State auto and light-duty gasoline-powered truck inspection and maintenance (I&M) program begun in January 1982 and the taxi I&M program begun in October 1977. The existing I&M program requires annual inspections of automobiles and light trucks to determine if CO and hydrocarbon emissions from the vehicles' exhaust systems are below emission standards. Vehicles failing the emissions test must undergo maintenance and pass a re-test to be registered in New York State. Heavy-duty vehicle emission estimates reflect local engine displacement and vehicle loading characteristics. These data were obtained from the DEP and are based on vehicle registration data. VEHICLE OPERATING CONDITIONS Auto operating conditions used in the and future emission calculations were obtained from data supplied by DEP, Bureau of Science and Technology Report No. 34 (Revised). Light-duty truck operating conditions for Manhattan were based on data supplied by the former Tri-State Regional Planning Association, now the New York Metropolitan Transportation Coordinating Council (NYMTC). Table 10-2 summarizes these thermal state conditions used in the analysis. 10-8

Chapter 10: Air Quality TRAFFIC DATA Traffic data for the air quality analysis were derived from traffic counts and other information developed as part of the project's traffic analysis described in Chapter 9, Transportation. For the air quality analysis, a screening was conducted to determine the worst-case time periods for analysis at critical intersections, for each alternatives. The screening analysis was used to determine the weekday peak period that would be subjected to full-scale microscale analysis, based on traffic volumes and approach delays and the corresponding levels of service for the Build alternatives. The time periods selected for the mobile source analysis predict the greatest significant traffic impacts due to diversions as a result of the Build alternatives and the largest overall traffic volumes and represent generally constrained traffic conditions in each of the study area zones. At some highly congested locations, microscale analysis was necessary for both the AM and PM weekday peak periods. Table 10-2 Vehicle Operating Conditions Assumed in the Air Quality Analysis Analysis Period Vehicle AM PM Local Autos (Downtown) Percentage Cold (Non Catalytic) 2.1 Percentage Cold (Catalytic) 3.2 Percentage Hot (Catalytic) 0.9 Local Autos (Valley) Percentage Cold (Non Catalytic) 23.3 Percentage Cold (Catalytic) 29.7 Percentage Hot (Catalytic) 3.3 Local Autos (Midtown) Percentage Cold (Non Catalytic) 5.9 21.6 Percentage Cold (Catalytic) 6.1 27.6 Percentage Hot (Catalytic) 1.4 3.9 Local Autos (Uptown) Percentage Cold (Non Catalytic) 22.5 19.8 Percentage Cold (Catalytic) 22.8 26.3 Percentage Hot (Catalytic) 0.6 4.2 Light-Duty Gasoline Trucks Percentage Cold (Non Catalytic) 3.2 3.2 Percentage Cold (Catalytic) 4.1 4.1 Percentage Hot (Catalytic) 45.3 45.3 The peak 8-hour concentrations were determined by applying a conservative persistence factor of 0.77 to the maximum predicted 1-hour local impact values. This persistence factor takes account of the fact that over 8 hours, vehicle volumes will fluctuate downward from the peak, speeds may vary, and wind directions and speeds will change somewhat as compared with the conservative assumptions used for the single highest hour. 10-9

Manhattan East Side Transit Alternatives MIS/DEIS BACKGROUND CONCENTRATIONS Background concentrations are those pollutant concentrations not directly accounted for through the modeling analysis (which directly accounts for vehicular-generated emissions on the streets within 1,000 to 1,600 feet and line-of-sight of the receptor location). Background concentrations must be added to modeling results to obtain total pollutant concentrations at a prediction site. One-hour and 8-hour average CO background concentrations used in the future (2020) analysis were 6.0 and 2.9 ppm for the 1- and 8-hour predictions, respectively. These values, obtained from DEP, are based on CO concentrations measured at DEC monitoring stations and are adjusted to reflect the reduced vehicular emissions expected in the analysis year. This decrease reflects the increasing numbers of federally mandated lower-emission vehicles that are projected to enter the vehicle fleet as older, higher polluting vehicles are retired (i.e., vehicle turnover), and the continuing benefits of the New York I&M program. MOBILE SOURCE RECEPTOR LOCATIONS The air quality receptor sites in the different study area zones selected for microscale analysis are shown in Table 10-3 and Figures 10-1 through 10-4. Receptor sites were placed at locations expected to experience increased vehicular emissions due to traffic diversions resulting from the Build alternatives, with particular consideration for congested intersections in each study area zone. Because of the relatively low levels of traffic congestion and the minimal traffic effects of the various alternatives there, no receptor sites were selected for analysis in the East Harlem zone. Table 10-3 Mobile Source Receptor Locations Receptor Time Period Site Study Area Zone Location Analyzed 1 Lower Manhattan Pearl Street and Peck Slip AM 2 Lower East Side Houston Street and Avenue C PM 3 Lower East Side/East 14th Street and Second Avenue PM Midtown 4 East Midtown/Upper East 59th Street and Second Avenue AM/PM Side 5 Upper East Side 62nd Street and Second Avenue AM/PM 6 Upper East Side/East Harlem 96th Street and First Avenue PM As discussed in the discussion of traffic data above, a screening was conducted based on traffic volumes and approach delays and the corresponding levels of service for the Build alternatives. The screening analysis determined the intersections that would be subjected to full-scale microscale analysis for the future alternatives. Candidate intersections (intersections analyzed as part of the transportation chapter) were ranked based on the methodology developed by the New York State Department of Transportation (NYSDOT) and DEC to evaluate critical locations. 10-10

Chapter 10: Air Quality The receptor sites selected for analysis represent the worst traffic conditions in each study area zone, and therefore are the locations where the greatest air quality impacts and maximum changes in the CO concentrations would be expected. They are locations in the study area zones where the largest levels of traffic diversions would be expected and overall constrained traffic conditions exist. Multiple receptor sites were modeled at each of these intersections (i.e., receptors were placed along the approach and departure links at spaced intervals). PREDICTING CARBON MONOXIDE CONCENTRATIONS IN THE STUDY AREA As noted previously, receptors were placed at multiple sidewalk locations next to the six intersections under analysis. The receptor with the highest predicted CO concentrations was used to represent these intersection sites for the project alternatives. CO concentrations were calculated for each receptor location, at each intersection, for the weekday peak periods specified above. B. EXISTING CONDITIONS EXISTING MONITORED AIR QUALITY CONDITIONS (1996) Monitored concentrations of CO, SO 2, particulates, NO 2, lead, and ozone ambient air quality data for the area are shown in Table 10-4. These values are the most recent monitored data available that have been published by DEC for these locations. As shown in the table, the nearest monitoring stations for CO, SO 2, PM 10, NO 2, and lead are in Manhattan. The nearest monitoring station for ozone is in Queens. There were no monitored violations of the NAAQS for the pollutants at these sites in 1996. Table 10-4 Representative Monitored Ambient Air Quality Data Concentrations Number of Exceedances of Federal Standard Second Sec- Pollutant Location Units Period Mean Highest Highest Primary ondary CO Bloomingdale s 8-hour 6.4 6.3 0 0 1-hour 11.7 10.8 0 0 SO2 P.S. 59 ppm Annual 0.015 0 24-hour 0.060 0.047 0 3-hour 0.105 0.086 0 Respirable Madison Avenue 3 µg/m Annual 45 0 0 Particulates and 46th Street 24-hour 148 90 0 0 (PM 10) NO P.S. 59 ppm Annual 0.042 0 0 2 3 Lead Madison Avenue µg/m 3-month 0.060 0.050 0 0 O Queens College ppm 1-hour 0.123 0.108 0 0 3 Source: New York State Air Quality Report, Ambient Air Monitoring Systems, Annual 1996 DAR-97-1. 10-11

Manhattan East Side Transit Alternatives MIS/DEIS C. PROBABLE IMPACTS OF THE PROJECT ALTERNATIVES CARBON MONOXIDE ANALYSIS A microscale CO analysis was performed for each of the project alternatives for the year 2020. The analysis followed the general modeling procedures that are discussed above. Vehicular traffic estimates, which are outlined in Chapter 9, were employed in the air quality mobile source modeling. Table 10-5 shows the results of this analysis for each alternative. No 1-hour values are shown since predicted concentrations are far below the respective standard. In addition, 8-hour values are the most critical for impact assessment. The values shown for CAL3QHC modeling are the highest predicted concentrations for each receptor location. At receptor sites 4, 5, and 6, the maximum predicted CO future No Build concentrations using the first-level CAL3QHC modeling were found to be greater than the applicable ambient air quality standards. Therefore, CAL3QHCR, the refined version of the model was employed. The values shown for refined CAL3QHCR modeling are the second highest predicted concentrations for each receptor location. Table 10-5 Maximum Predicted 8-Hour Average Carbon Monoxide Concentrations for the Project Alternatives Receptor Time No Site Location Period Build TSM Build 1 Build 2 1 Pearl Street and Peck Slip AM 4.1 4.4 2 Houston Street and Avenue C PM 5.6 5.7 3 14th Street and Second Avenue PM 4.7 6.4 4 59th Street and Second Avenue* AM/PM 7.1 7.1 5 62nd Street and Second Avenue* AM/PM 7.4 7.4 6 96th Street and First Avenue* PM 6.9 6.9 Notes: * CAL3QHCR results. CO concentrations were predicted for project alternatives only at receptor sites where localized traffic conditions are expected to change because of those alternatives. The 8-hour NAAQS for CO is 9 ppm. NO BUILD ALTERNATIVE As shown in Table 10-5, the future (2020) maximum predicted 8-hour average CO concentrations for the No Build Alternative are below the 8-hour NAAQS of 9 ppm at all receptor sites analyzed. At receptor sites 4, 5, and 6, the maximum predicted CO future No Build concentrations using the first-level CAL3QHC modeling were found to be greater than the applicable ambient air quality standards. Therefore, CAL3QHCR, the refined version of the model was employed. Using CAL3QHCR, the No Build predicted value for those analysis sites were less than the 8-hour NAAQS. 10-12

Chapter 10: Air Quality TSM ALTERNATIVE As indicated by the table and described earlier, the TSM Alternative was not predicted to affect traffic conditions significantly in Lower Manhattan, the Lower East Side, or East Harlem. Consequently, analyses were performed only for receptor sites 4, 5, and 6, which are located in East Midtown and on the Upper East Side. As noted earlier, the maximum predicted future CO concentrations predicted using the first-level CAL3QHC modeling were found to be greater than the applicable ambient air quality standards at these receptor sites. Therefore, CAL3QHCR, the refined version of the model, was employed. Using CAL3QHCR, the TSM Alternative would not result in any violations of the CO standards or any significant adverse impacts at the receptor locations analyzed. BUILD ALTERNATIVE 1 The operation of a new subway under Second Avenue under Build Alternative 1 is not expected to result in any significant diversions of traffic, as discussed in Chapter 9. Therefore, no significant change is expected in CO levels compared with the No Build Alternative in all of the study area zones. No mobile source modeling was performed for this alternative. BUILD ALTERNATIVE 2 As described above for Build Alternative 1, the new subway under Second Avenue would not be expected to result in any significant adverse air quality impacts, and no detailed modeling was required. The light rail transit component of Build Alternative 2 would, however, result in changes to traffic patterns in Lower Manhattan and on the Lower East Side and therefore warrants mobile source air quality modeling at receptor sites in those study area zones. As shown in Table 10-5, the maximum predicted future CO concentrations would not exceed the CO standards or result in any significant adverse impacts at those receptor sites. Build Alternative 2 would have only minor effects on general traffic conditions in the East Midtown study area zone. Although the 23rd Street corridor would be significantly impacted by this Build alternative, the traffic conditions for East Midtown under the TSM Alternative were found to be far worse as part of the screening analyses conducted to determine air quality receptor locations, and the results of the mobile source modeling analysis for this study area zone under the TSM Alternative predicted no violations of the CO standards or any significant adverse air quality impacts. Therefore, Build Alternative 2 also would not result in any air quality impacts in this study area zone, and no mobile source modeling was performed. REGIONAL (MESOSCALE) POLLUTANT IMPACTS A mesoscale analysis is typically performed by computing pollutant burdens within a project's overall study area. Pollutant burdens represent total expected quantities of pollutant emissions for a region for a defined time period. Pollutant burdens were computed for the annual quantities of CO, VOCs, and NO x that would be emitted due to changes in vehicular activity within the whole network for each of the project alternatives. Vehicular pollutant burdens were computed based on the most recent EPA vehicle emission estimating procedures, MOBILE5B, and on the vehicle miles traveled (VMT) for the analysis year (2020). 10-13

Manhattan East Side Transit Alternatives MIS/DEIS Pollutant burdens provide an indication of the general change in air quality. They are particularly useful for assessing the relative change in the concentration of the reactive air pollutants hydrocarbons and NO x and resultant concentrations of photochemical oxidants. In addition, CO burdens are examined to determine the general effect of changes in vehicular activity on background levels of this pollutant. Average travel speeds and VMT within the network were based on the project s transportation model (described in Chapter 9). Thermal state data was based on values for Manhattan obtained from New York State DEC. For each pollutant, an appropriate temperature is used to compute the various speed-dependent emission factors. For CO, 50E Fahrenheit was used, while for VOCs and NO, 78.3E Fahrenheit was used, reflecting the summer ozone season. x The effect of each Build alternative was assessed based on its relative burden of emissions compared with the No Build Alternative. The results of the analysis are shown in Table 10-6, both in tons per year and in terms of the percent change from the No Build Alternative. The Build alternatives all result in predicted reductions of annual pollutant burdens with respect to the No Build Alternative. Therefore, the Build alternatives provide modest improvements in regional air quality, with Build Alternative 1 having the largest benefit. Table 10-6 Regional Mobile Source Pollutant Burdens Relative to the No Build Alternative Incremental Pollutant Burdens (tons per year) CO VOCs NO x Alternative No. Percent No. Percent No. Percent TSM Alternative -34.7-0.019% -2.5-0.019% -2.9-0.019% Build Alternative 1-43.3-0.023-3.1-0.023-3.7-0.023 Build Alternative 2-13.3-0.007% -1.0-0.007% -1.1-0.007% CONCLUSIONS Overall, none of the project alternatives would result in any new violations of National Ambient Air Quality Standards or significant adverse air quality impacts at any of the receptor sites analyzed. Since those receptor sites were chosen to represent the greatest traffic impacts, and therefore the greatest potential for air quality impacts, the analysis thus demonstrates that none of the alternatives would result in violations of air quality standards or significant air quality impacts at other locations in the study area as well. For a discussion of the potential for air quality impacts during construction, see Chapter 15, Construction and Construction Impacts. Further, the mesoscale analysis predicts that lower pollutant burdens of CO, VOCs, and NO x would result with all the Build alternatives. Therefore, all Build alternatives conform to the purpose of the SIP and the 1990 CAAA. 10-14

Chapter 10: Air Quality CONSISTENCY WITH THE NEW YORK STATE AIR QUALITY IMPLEMENTATION PLAN All the mobile source receptor locations analyzed under the No Build and Build alternatives scenarios would have predicted CO levels less than the corresponding ambient air quality standards. Therefore, construction and operation of the Build Alternatives by 2020 would be consistent with the SIP for CO. In addition, the Build alternatives would not result in a significant increase in vehicular miles traveled in the New York metropolitan region, and thus would not exacerbate ozone levels. Therefore, the Build alternatives would be consistent with the SIP for ozone. D. MITIGATION The implementation of the proposed traffic mitigation for the Build alternatives discussed in Chapters 9 and 18 would not significantly change the air quality modeling inputs, and therefore would not result in any significant effect on the maximum predicted CO concentrations at the air quality receptor locations. It is possible that the proposed mitigation would result in slightly lower CO concentrations at some locations. Therefore it is expected that the results with the proposed traffic mitigation measures would not result in any violations of the CO standards or any significant adverse impacts at any of the receptor locations selected for microscale analysis in all the study area zones. Since no significant adverse air quality impacts are predicted for any of the project s Build alternatives, no air quality mitigation is required. 10-15