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7 The following sections provide overviews of the predominant air quality standards and regu- lations as they apply to airports. 2.1 Clean Air Act (CAA) and the National Environmental Policy Act (NEPA) For decades following the establishment of commercial-service airports in the United States, the common complaint from neighboring communities was aircraft noise, which was con- sidered more of an annoyance as opposed to a health concern. This focus on noise continued through the introduction of the large commercial turboprop-engine aircraft in the 1950s and the turbofan engines in the 1960s. However, with the initial enactment of the Air Pol- lution Control Act in 1955, and then the Clean Air Act (CAA) in 1970, and the Clean Air Act Amendments (CAAA) in 1990, emissions and air quality were given increasingly greater scrutiny. The 1990 CAAA brought sweeping changes that included various measures to further control and regulate emissions. Along with the CAA in 1970, the National Environmental Policy Act (NEPA) was enacted to serve as a national policy on protecting the environmentârequiring environmental evaluations for federal actions with significant impacts on the environment. In compliance with this, the FAA is required to provide an accounting of emissions projected to occur from aircraft and other sources of harmful emissions at airports when seeking to expand or improve operations. As part of the NEPA process, FAA is required to evaluate all potential environmental impacts caused by an action at an airport by comparing build and alternative cases with those of the corresponding C H A P T E R 2 Ambient Air Quality Standards and Regulations Standards Versus Pollutants Primary and Secondary Standards refer to the ambient standards established as the National Ambient Air Quality Standards (NAAQS) for criteria pollutants for the protection of public health (primary standards) and protection of the environment (secondary standards). Primary and Secondary Pollutants refer to whether pollutants are emitted directly from a source (primary pollutantsâe.g., NOx, CO, VOCs, PM2.5, etc.) or formed in the atmosphere through chemical reactions and/or physical processes (secondary pollutantsâe.g., O3, PM nitrates, PM sulfates, etc.).
8 Understanding Airport Air Quality and Public Health Studies Related to Airports no-build (baseline) case. The amendments also established the General Conformity Rule that sets thresholds above which an air quality assessment would be required in areas of the country already experiencing poor air quality (i.e., within maintenance and nonattainment areas). 2.2 National Ambient Air Quality Standards (NAAQS) Under the CAA, ambient air concentration limits of six (6) criteria pollutants having adverse human health and environmental effects were established by the EPA as the National Ambient Air Quality Standards (NAAQS) summarized in Table 2-1. The NAAQS reflect concentration values (e.g., Âµg/m3) that have been developed through various scientific and health studies. The EPA defines the NAAQS on two levels: primary and secondary. Primary standards protect public health, particularly for sensitive populations such as asthmatics, children, and the elderly. Secondary standards address public welfare by protect- ing against the reduction of visibility and damage to animals, crops, vegetation, and buildings. The NAAQS have been updated frequently during the past two decades and the current stan- dards can be found on the EPA website at http://epa.gov/air/criteria.html. The EPA uses the NAAQS values for each criteria pollutant to signify the health status of each county within the United States. The following designations are used to signify the status of each county: â¢ NonattainmentâAny area that does not meet (or that contributes to ambient air quality in a nearby area that does not meet) the national primary or secondary ambient air quality standard for the pollutant. â¢ AttainmentâAny area . . . that meets the national primary or secondary air quality standard for the pollutant. â¢ UnclassifiableâAny area that cannot be classified on the basis of available information as meet- ing or not meeting the national primary or secondary air quality standards for the pollutant. Nonattainment areas are also further designated as being marginal, moderate, serious, severe, or extreme depending on how much the areaâs concentrations are above the ambient standards. Based on the county(ies) in which an airport is located, it must abide by the attainment status of the county for all NEPA and General Conformity evaluations. Table 2-1. National Ambient Air Quality Standards. Pollutant Averaging Period Primary Standards Secondary Standards Carbon Monoxide (CO) 8 hours 9 ppm None 1 hour 35 ppm Lead (Pb) Rolling 3-month average 0.15 Âµg/m 3 Same as Primary Nitrogen Dioxide (NO2) Annual 53 ppb Same as Primary 1 hour 100 ppb None Particulate Matter (PM10) 24 hours 150 Âµg/m3 Same as Primary Particulate Matter (PM2.5) Annual 12 Âµg/m 3 15.0 Âµg/m3 24 hours 35 Âµg/m3 Same as Primary Ozone (O3) 8 hours 0.075 ppm Same as Primary Sulfur Dioxide (SO2) 1 hour 75 ppb 3-hour 0.5 ppm Source: http://epa.gov/air/criteria.html
Ambient Air Quality Standards and Regulations 9 While the NAAQS include PM10 and PM2.5, currently there are no standards for much smaller PM size ranges such as the ultrafine range (i.e., PM with an aerodynamic diameter smaller than 0.1 Âµm). Similarly, there are no general, ambient standards for hazardous air pollutants (HAPs) also known as air toxics (see Section 2.5). However, it should be noted that the Occupational Safety & Health Administration (OSHA) and the National Institute for Occupational Safety and Health (NIOSH) have concentration standards for workplaces in the form of permissible exposure limits (PELs) and recommended exposure limits (RELs). These standards would apply to airport employees. 2.3 State Implementation Plan The 1970 CAA required states to develop a legislative plan to implement the NAAQS and ensure the standards are met and maintained. The plan referred to is the State Implementation Plan (SIP), and includes many other provisions related to control of emissions from industry. A SIP is intended to serve two purposes, to demonstrate how a stateâs air quality management program will imple- ment additional or revised NAAQS, and identify the emission control strategies relied on to meet and/or maintain the NAAQS. An inventory of estimated emissions from airports located within each state, and the emissions projected to occur in the future from those airports, are included in the statesâ SIP budgets and are considered in the statesâ plans to reduce further emissions of harm- ful pollutants and maintain pollutant concentrations at an acceptable level. 2.4 General Conformity To assess the impact of new projects on a SIP, either General Conformity or Transportation Conformity evaluations need to be performed. Most airport projects require General Confor- mity evaluations that include the quantification of the expected net emissions from a project (i.e., emissions beyond the status quo or no-build case). These are compared to established de minimis levels to determine if they will have a significant impact on the overall stateâs emis- sions inventory. Depending on the magnitude of the project emissions levels, an evaluation of its compliance with the SIP may need to be made (i.e., whether the regional emissions budget can absorb the project emissions). In addition, atmospheric dispersion modeling may need to be conducted to better assess the impact of the project emissions. 2.5 Emissions Standards and Permits To control emissions, the New Source Performance Standards (NSPS) serve as federal emissions standards that apply to new and modified sources on a category basis. The standards are typically specified in terms of emissions per amount of fuel/feedstock or the product (e.g., 0.60 pounds of NOx per million BTU of coal for steam electric power plants). Similar to the NSPS, the National Emission Standards for Hazardous Air Pollutants (NESHAP) were established to control mass emissions of HAPs (air toxics) through the promotion of technology-based standards for each facility type. These standards apply to equipment used at airports such as power generators, boilers, etc. Section 112 of Title I of the CAA includes provisions for implementing NESHAP and lists each of the close to 200 HAP species, some of which are exemplified below: â¢ Acetaldehyde, â¢ Benzene, â¢ 1,3-Butadiene, â¢ Formaldehyde, â¢ Toluene, â¢ Trichloroethylene, and â¢ Lead compounds.
10 Understanding Airport Air Quality and Public Health Studies Related to Airports The full list can be found at the EPA air toxics website, http://www.epa.gov/ttn/atw/. Emissions and concentrations of each HAP species will vary at airports, with many below the detection limits of ambient monitoring and sampling equipment. It should be noted that lead is both a criteria pollutant and a HAP. In addition to the NSPS and NESHAPs, there are various rules to limit and control the release of air emissions. The New Source Review (NSR) permitting program was established as part of the 1977 Clean Air Act Amendments, and is intended to protect air quality degradations, espe- cially in pristine areas such as National Parks. Under the NSR, there are three preconstruction permits that control the source construction, emissions limits, and source operations: preven- tion of significant deterioration (PSD), nonattainment NSR, and minor NSR. These permits are required based on the equipment size and air quality status of the region, and airports must apply for permits accordingly for new equipment. The CAA Title V permits are named after Title V of the 1990 CAAA, and they generally apply to all major sources including those operated at airports. These operating permits provide permission on a facilitywide basis and cover emissions limits and monitoring requirements, recordkeeping, and reporting. Title V permits are usually issued by state agencies and are legally enforceable documents. Airports must maintain these permits for their equipment and follow the reporting requirements. 2.6 Indoor Air Pollution Human health concerns typically focus on the quality of outdoor air with the correspond- ing NAAQS set to protect and promote human health and welfare from ambient air quality impacts. In contrast, the EPA currently does not regulate indoor air quality although guidance from the EPAâs Indoor Environments Division (IED) is offered on educating and helping the public reduce exposures to indoor pollutants. Both gaseous and PM pollutants can be gener- ated from various indoor sources including, but not limited to, combustion sources (e.g., using oil, gas, etc.), smoking (e.g., tobacco use), cleaning solutions, building materials, and furniture (e.g., formaldehyde released from pressed-wood products). In addition to these sources, indoor air pollution can escalate if inadequate ventilation exists and not enough outdoor air is allowed to mix with the indoor air, thus diluting indoor air pollutant concentrations. While not the main focus for airports, indoor air still needs to be considered to allow for a comprehensive understanding of potential public health impacts from air pollution. Indoor air pollution at airports can occur for both airport personnel (e.g., within maintenance facilities, boiler room, offices, etc.) and the public/passengers (e.g., within terminal buildings, aircraft, etc.). In general, indoor air pollution is not a concern at airports as there no significant indoor sources and, typically, buildings are well ventilated.