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1 1 (July 06, 2020)

handle is hein.crs/govdard0001 and id is 1 raw text is: -F$h. Updated July 6, 2020 Ozone and Particulate Matter Air Standards: EPA Review The Clean Air Act (CAA) requires the U.S. Environmental Protection Agency (EPA) to review standards for national ambient air quality every five years. In 2018, EPA announced strategies to expedite the National Ambient Air Quality Standard (NAAQS) review while concurrently disbanding a pollutant-specific scientific review panel that has historically advised agency staff during their reviews. Although the CAA allows the EPA Administrator to specify the procedures for review of the NAAQS, past EPA reviews and revisions have garnered considerable congressional oversight. This In Focus discusses EPA's current NAAQS reviews for ozone and particulate matter (PM), which EPA had sought to complete in 2020, and issues of potential interest to Congress. Ozone and PM are two of six principal pollutants referred to as criteria pollutants for which EPA has promulgated NAAQS under the CAA (42 U.S.C. §7408(a)(1)). Ground-level ozone, the primary component of smog, is formed when nitrogen oxides (NOx) react with volatile organic compounds (VOCs) in sunlight. Ground-level ozone is associated with health effects, such as aggravated asthma, chronic bronchitis, heart attacks, and premature death. EPA has identified natural and anthropogenic sources of ozone and ozone precursors (e.g., NOx and VOCs), including factories, lightning, power plants, vegetation, vehicles, volatile chemical products (e.g., paints and solvents), and wildfires. PM refers to a mixture of solid particles and liquid droplets in the atmosphere. PM components may include acids, organic chemicals, metals, and soil or dust particles. The size of PM varies, ranging from tiny particles that can be seen only through a high-power microscope to larger particles (e.g., soot). Exposure to PM has been associated with adverse health effects (e.g., aggravated asthma, chronic bronchitis, and premature death). PM has also been linked with haze formation and other ecological effects. Typical sources of fine PM (PM2.5) measured at 2.5 micrometers or less in diameter-include emissions from vehicles, smokestacks, and fires. Coarse PM (PMo) generally measuring 10 micrometers or less in diameter is often associated with dust from paved and unpaved roads, construction and demolition operations, certain industrial processes and agriculture operations, and biomass burning. In addition, precursor emissions (e.g., sulfur oxides, NO, and VOCs) contribute to the formation of secondary PM. PM2.5 contains a much greater portion of secondary particles than PM0 does. Notwithstanding air quality progress since 1970, ozone and PM concentrations currently exceed the NAAQS in some areas (nonattainment areas). Table 1 lists these NAAQS and the estimated population in nonattainment areas. Table I. Selected NAAQS and the Estimated U.S. Population in Corresponding Nonattainment Areas Estimated U.S. Primary Population in NAAQS Standard Nonattainment Areas 2015 Ozone 70 ppb (8-hour) 122 million 2012 Fine PM 12.0 pg/M3 (Annual) 21 million 1987 Coarse PM IS0 pg/M3 (24-hour) 6 million Source: CRS, as adapted from EPA Green Book (May 31, 2020), which lists nonattainment areas (https://www.epa.gov/green-bool<). Estimated population based on 2010, rounded to nearest million. Notes: Units of measure are parts per billion (ppb) and micrograms per cubic meter of air (pg/M3). See 40 C.F.R. Part 50 for detailed NAAQS. Table presents the most recent PM and ozone NAAQS. NAAQS do not directly limit emissions. Rather, NAAQS are concentration-based standards for ambient (outdoor) pollution. Under the CAA, Congress mandated that EPA establish two types of NAAQS for each criteria pollutant a primary NAAQS, which must protect public health with an adequate margin of safety, and a secondary NAAQS, which must protect public welfare from any known or anticipated adverse effects (42 U.S.C. §7409(b)). Public welfare includes damage to crops, vegetation, property, building materials, and climate (42 U.S.C. §7602(h)). The CAA establishes a framework for EPA to set NAAQS based on the latest scientific knowledge through a notice- and-comment rulemaking process (42 U.S.C. § §7408, 7409). The CAA requires EPA to review the NAAQS and the science upon which they are based every five years and then revise the NAAQS if necessary. The CAA also requires EPA to appoint an independent scientific review committee composed of seven members, which has become the Clean Air Scientific Advisory Committee (CASAC). The act directs CASAC to review the NAAQS every five years and recommend to the EPA Administrator any new national ambient air quality standards and revisions ... as may be appropriate (42 U.S.C. §7409(d)(2)). , ' A'\, Rs\-,,kv ,of kbte, NAAQ§' Beyond the aforementioned CAA requirements, procedural aspects of the NAAQS review are generally at the discretion of the EPA Administrator. Historically, the agency has undertaken a multi-step process to review each NAAQS. Each NAAQS review typically begins with a planning phase in which EPA seeks public input and ~fl:O~ p\w gnom ggmm mppm qq\ a , q 'S I 11LULANUALiN,

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