Air quality standards ozone

There has been considerable improvement, especially in industrial areas, in U.S. air quality since the adoption of the Clean Air Act of 1972. Appreciable reductions in particulate emissions and in SO 2 levels are especially evident. In 1990, however, almost every metropolitan area was in nonattainment status on ozone air quality standards 50 metropolitan areas exceeded the CO standard and between 50 and 100 exceeded the PAI10 standard for particulate level (29). 

TABLE 26.9 Alternative Statistical Forms of the Ozone Air Quality Standard"... 

Let us now analyze each of the four forms of the ozone air quality standard given in Table 26.9 from the point of view that ozone concentrations can be represented by a Weibull distribution. 

Evaluation of Alternative Forms of the Ozone Air Quality Standard with 1971 Pasadena, California, Data Earlier, 1971 hourly average and maximum daily hourly average ozone mixing ratios at Pasadena, California, were fit to Weibull distributions. We now wish to evaluate the four forms of the ozone air quality standard with these data. For convenience all mixing ratios values will be given as pphm rather than ppm. 

Nine cities with the most serious ozone pollution were required by the 1990 regulations to use reformulated gasolines, and another 87 cities that were not meeting the ozone air-quality standards were given the option of using these gasolines. 

Many of the combustion power plants in the U.S. will be affected by NO, and ozone air quality standards. The new regulations for ozone non-attainment areas will affect virtually all existing power plants located in urban areas, particularly in Southern California s South Coast Air Quality Management District (SCAQMD) and throughout the Northeast. The... 

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. 

Sources Air Quality Criteria for Ozone and Other Photochemical Oxidants, EPA 600/8-78-004. U.S. Environmental Protection Agency, Research Triangle Park, NC, April 1978 Revisions to National Ambient Air Quality Standards for Photochemical Oxidants, Fed. Reg. Part V, Feb. 9, 1979, pp. 8202-8237,... 

The new 0.08 standard is much stronger and more protective than Uie old standtird of 0.12. It will extend new health protections to 35 million people, bringing to 113 million tlie number of Americans protected by the air quality standard for ozone... 

In Mexico City, several air quality parameters are measured continuously by an Automated Monitoring Network operated by the Under Secretariat of Ecology. Carbon monoxide, particulate matter, sulfur dioxide, nitrogen oxide, and ozone are the contaminants exceeding Air Quality Standards. Emissions produced by 2.7 million vehicles and 35,000 commercial and industrial outfits are not easily dispersed in a Valley located at 2240 m and surrounded by two mountain chains which hinder air circulation. An Integral Program, recently established to alleviate pollution, is briefly described. 

A long and difficult task will be confronted, in particular to bring ozone within the air quality standards, as the physics and chemistry of ozone formation in the MCMA are not sufficiently understood. 

FIGURE 7.3 In 1984, 14 years after the passage of the Clean Air Act, significant areas of the United States were still in violation of National Ambient Air Quality Standards (NAAQS) for ozone. Courtesy, Environmental Protection Agency. 

A critical question concerning atmospheric concentrations of ozone and other photochemical oxidants is What fraction of the observed values in each locale can be controlled by reduction of emissions Some contend that natural background concentrations exceed the federal ambient air quality standard (0.08 ppm). Another point of view is that background ozone concentrations rarely exceed about 0.05-0.06 ppm at the surface and that higher concentrations are caused by man-made sources. 

Nonurban oxidant measurements in Ohio were reported by Neligan and Angus. Concentrations of 0.18 and 0.12 ppm were reported for rural sites in Wilmington and McConnelsville, respectively. At the same time, urban sites had similar concentrations. However, the nonurban sites violated the ambient air quality standard more frequently than the urban sites. Trajectory analysis showed that ozone concentrations of 0.04-0.06 ppm were found in air masses that had not passed over anthropogenic hydrocarbon sources. These may have been examples of naturally occurring oxidant. Airborne hydrocarbon bag samples were obtained over 6-min... 

A dramatic departure of ozone measurements from total oxidant measurements has b Mi reported for the Houston, Texas, area. Side-by-side measurements suggested that either method was a poor predictor of the other. Consideration was given to known interferences due to oxides of nitrogen, sulfur dioxide, or hydrogen sulfide, and the deviations still could not be accounted for. In the worst case, the ozone measurements exceeded the national ambient air quality standard for 3 h, and the potassium iodide instrument read less than 15 ppb for the 24-h period. Sulfur dioxide was measured at 0.01-0.04 ppm throughout the day. Even for a 1 1 molar influence of sulfur dioxide, this could not explain the low oxidant values. Regression analysis was carried out to support the conclusion that the ozone concentration is often much higher than the nonozone oxidant concentration. 

The technol( for the routine measurement of the nitrogen oxides (nitrogen dioxide and nitric oxide) is fairly well advanced. The epa is on the verge of officially proposing that chemiluminescence produced by the reaction of nitric oxide with ozone be the reference method for nitrogen dioxide.This method is even more suitable for nitric oxide. Because no national air quality standard has been promulgated for nitric oxide, no reference method will be specified. However, its measurement in the atmosphere is crucial for establishing the relation of its emission to the formation of atmospheric ozone and other photochemical oxidants. 

In interpreting the results of human experimental studies with pure ozone in relation to the oxidant standard, it must be remembered that the other oxidants ordinarily present in smog were absent. Conceivably, a larger difference may be necessary between the lowest concentration of pure ozone at which an observed effect occurred and the air quality standard than between the lowest concentration of oxidant mixtures and the standard. 

The development of criteria for setting air quality standards requires a sufficient data base relating a given dose (concentration of pollutant X duration of exposure) of oxidant (e.g., ozone or PAN) to some mean-... 

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