Standards, air quality

Under the terms of the Clean Air Act of 1970, as amended in 1990, the Environmental Protection Agency is required to establish National Ambient Air Quality Standards (NAAQS) for pollutants considered to be hazardous to public health and the environment. These standards are of two types primary and secondary. Primary standards apply to sensitive members of the population, including the elderly, young children, and people who have respiratory disorders. Secondary standards apply to the general public and include risks to other parts of the environment, including visibility, animals, crops, vegetation, and buildings. 

The NAAQS in effect as of June 2004 are summarized in the chart on pages 53-54. Note that only six air pollutants are included in this table carbon monoxide, nitrogen dioxide, ozone, lead, particulate matter, and sulfur dioxide. These pollutants are called criteria pollutants. 

The quality of the nation s air has clearly improved since Earth Day 1970. Air quality measurements for all six criteria pollutants have improved, in some cases quite dramatically. The battle to control pollution is hardly over, however. As this chapter has indicated, emissions of many pollutants continue to increase. The dialogue continues between those who wish to regulate air quality more rigorously and those who prefer to move more slowly and protect economic growth. There seems little doubt that that debate will continue well into the future. 

POLLUTANT PRIMARY STANDARDS AVERAGING TIMES SECONDARY STANDARDS 

Carbon monoxide 9 ppm (10 mg/m ) 35 ppm (40 mg/m ) 8-hour 1-hour None None 

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COLORANTS FORFOOD,DRUGS,COSTffiTICS AND TffiDICALDEVICES] (Vol 6) NAAQS. See National Ambient Air Quality Standard. 

Table 3. National Ambient Air Quality Standards for Criteria Pollutants ...

United States Congress, Public Eaw 101-549, MnMct toMmend the Clean Air Met to Provide for Attainment and Maintenance of Health Protective National Ambient Air Quality Standards, andfor Other Purposes, Nov. 15,1990. 

National Ambient Air Quality Standards. Under the Clean Air Act, six criterion pollutants, ie, pollutants of special concern, have been estabhshed by the EPA sulfur oxides (SO ), particulates, carbon monoxide (CO), nitrogen oxides (NO ), o2one (photochemical oxidants), and lead. National Ambient Air QuaUty Standards (NAAQS) were developed by EPA based on threshold levels of air pollution below which no adverse effects could be experienced on human health or the environment. 

ERA promulgated the basic set of current ambient air-quality standards in April 1971. The specific regulated pollutants were particulates, sulfur dioxide, photochemical oxidants, hydrocarbons, carbon monoxide, and nitrogen oxides. In 1978, lead was added. Table 25-1 enumerates the present standards. 

Prevention of Significant Deterioration (PSD) Of aU the federal laws placing environmental controls on industiy (and, in particular, on new plants), perhaps the most confusing and restrictive are the limits imposed for the prevention of significant deterioration (PSD) of air quahty. These limits apply to areas of the countiy that are already cleaner than required by ambient air-quality standards. This regula-toiy framework evolved from judicial and administrative ac tion under the 1970 Clean Air Act and subsequently was given full statutoiy foundation by the 1977 Clean Air Act Amendments. 

TABLE 25-1 National Primary and Secondary Ambient Air Quality Standards... 

It may be desirable to curtail transport of pollution to areas whose air is presently quite clean, even though, after such transport, the air quality of the area would be considerably cleaner than would be required by air quality standards. This concept is called prevention of significant deterioration of the air quality in such areas. It requires definition of how much deterioration can be considered insignificant. 

Because a filter sample includes particles both larger and smaller than those retained in the human respiratory system (see Chapter 7, Section III), other types of samplers are used which allow measurement of the size ranges of particles retained in the respiratory system. Some of these are called dichotomous samplers because they allow separate measurement of the respirable and nonrespirable fractions of the total. Size-selective samplers rely on impactors, miniature cyclones, and other means. The United States has selected the size fraction below an aerodynamic diameter of 10 /xm (PMiq) for compliance with the air quality standard for airborne particulate matter. 

NR = No index values reported at concentration levels below those specified by "alert level" criteria (Table 5-1). Annual primary National Ambient Air Quality Standard. 

The relationship of these response curves to ambient air quality is shown by lines A, B, and C, which represent the maximum or any other chose percentile line from a display such as Fig. 4-10, which shows actual air quality. Where the air quality is poor (line A), essentially all the adverse effects displayed will occur. Where the air quality is good (line C), most of the intermediate and long-term adverse effects displayed will not occur. Where the air quality is between good and poor, some of the intermediate and long-term adverse effects will occur, but in an attenuated form compared with those of poor air quality. These concepts will be referred to later in this text when air quality standards are discussed. 

There are several different strategies for air pollution control. The strategy just discussed and shown in Fig. 5-1 is called the air quality management strategy. It is distinguished from other strategies by its primary reliance on the development and promulgation of ambient air quality standards. 

Discuss the relative importance of air quality criteria and cost effectiveness in the setting of air quality standards. 

IDENTIFICATION AND QUANTIFICATION.—Such plan provisions shall expressly identify and quantify the emissions, if any, of any such pollutant or pollutants which will be allowed, from the construction and operation of major new or modified stationary sources in each such area. The plan shall demonstrate to the satisfaction of the Administrator that the emissions quantified for this purpose will be consistent with the achievement of reasonable further progress and will not interfere with the attainment of the applicable national ambient air quality standard by the applicable attainment date. 

Public Law 101-549, 101st Congress—November 15, 1990, An Act to Amend the Clean Air Act to provide for attainment and maintenance of health protective national ambient air quality standards, and for other purposes. 

How do exposure time and type of population influence the air quality standards established for the community and the workplace ... 

Table 12-4 are sufficient for an understanding of smog chemistry. The major undesirable components of photochemical smog are NOj, O3, SOj, H2SO4, PAN, and aldehydes. Air quality standards have been established in several countries for SO2, NO2, and O3 H2SO4 contributes to acidic deposition and reduction in visibility and PAN and aldehydes can cause eye irritation and plant damage if their concentrations are sufficiently high. 

The three major characteristics of particulate pollutants in the ambient atmosphere are total mass concentration, size distribution, and chemical composition. In the United States, the PM q concentration, particulate matter with an aerodynamic diameter <10 /nm, is the quantity measured for an air quality standard to protect human health from effects caused by inhalation of suspended particulate matter. As shown in Chapter 7, the size distribution of particulate pollutants is very important in understanding... 

Describe the rationale for the U.S. Environmental Protection Agency s establishment of a standard reference method for measurement of National Ambient Air Quality Standard air pollutants. 

The U.S. Environmental Protection Agency has established National Ambient Air Quality Standards (NAAQS) for protection of human health and welfare. These standards are defined in terms of concentration and hme span for a specific pollutant for example, the NAAQS for carbon monoxide is 9 ppmV for 8 hr, not to be exceeded more than once per year. For a state or local government to establish compliance with a National Ambient Air Quality Standard, measurements of the actual air quality must be made. To obtain these measurements, state and local governments have established stationary monitoring networks with instrumentation complying with federal specifications, as discussed in Chapter 14. The results of these measurements determine whether a given location is violating the air quality standard. 

Raw data must be analyzed and transformed into a format useful for specific purposes. Summary tables, graphs, and geographic distributions are some of the formats used for data display. Air quality information often consists of a large body of data collected at a variety of locations and over different seasons. Table 15-3 shows the tabular format used by the California Air Resources Board to reduce ozone hourly measurements to a format which shows information about compliance with air quality standards (6). The format has location, maximum values, annual means, and number of occurrences of hourly values above a given concentration as a function of the month of the year. One can quickly determine which areas are violating a standard, at what time of the year elevated concentrations are occurring, and the number of good data points collected. 

Annual United States National Primary Ambient Air Quality Standard promulgated in 1971 ... 

Sources Air Quality Criteria for Particulate Matter and Sulfur Oxides, final draft, U.S. Environmental Protection Agency, Research Triangle Park, NC, December 1981 Review of the National Ambient Air Quality Standards for Sulfur Oxides Assessment of Scientific and Technical Information, Draft OAQPS Staff Paper, U.S. Environmental Protection Agency, Research Triangle Park, NC, April 1982. 

Air quality standards prescribe pollutant levels that cannot legally be exceeded during a specific time period in a specific geographic area. Air quality standards are based on air quality criteria, with added safety factors as desired. 

United States National Primary and Secondary Ambient Air Quality Standard, attained when the expected number of days per calendar year with maximum hourly average concentrations above 0.12 ppm is equal to or less than 1, as determined in a specified manner... 

The main philosophical question that arises with respect to air quality standards is what to consider an adverse effect or a cost associated with air pollution. Let us examine several categories of receptors to see the judgmental problems that arise. 

Although air quality standards are based predominantly on biological criteria, students should understand the physical criteria that also deserve consideration. 

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