Urban ozone

Annual trends in urban ozone are much more subtle because of the complex interaction among precursors (hydrocarbons and oxides of nitrogen) and meteorology (including solar radiation) (Fig. 4-5). 

Hundreds of chemical species are present in urban atmospheres. The gaseous air pollutants most commonly monitored are CO, O3, NO2, SO2, and nonmethane volatile organic compounds (NMVOCs), Measurement of specific hydrocarbon compounds is becoming routine in the United States for two reasons (1) their potential role as air toxics and (2) the need for detailed hydrocarbon data for control of urban ozone concentrations. Hydrochloric acid (HCl), ammonia (NH3), and hydrogen fluoride (HF) are occasionally measured. Calibration standards and procedures are available for all of these analytic techniques, ensuring the quality of the analytical results... 

Aneja, V. P P. Roelle, and W. P. Robarge, Contribution of Biogenic Nitric Oxide in Urban Ozone Raleigh, NC, as a Case Study, Atmos. Environ., 31, 1531-1537 (1997). 

Dunker, A. M R. E. Morris, A. K. Pollack, C. H. Schleyer, and G. Yarwood, Photochemical Modeling of the Impact of Fuels and Vehicles on Urban Ozone Using Auto/Oil Program Data, Environ. Sci. Technol., 30, 787-801 (1996). 

MacGregor, L and H. Westberg, The Effect of NMOC and Ozone Aloft on Modeled Urban Ozone Production and Control Strategies, J. Air Waste Manage. Assoc., 40, 1372-1377 (1990). 

Russell, A., J. Milford, M. S. Bergin, S. McBride, L. McNair, Y. Yang, W. R. Stockwell, and B. Croes, Urban Ozone Control and Atmospheric Reactivity of Organic Gases, Science, 269, 491-495... 

The vapors of this highly toxic synthetic solvent (it s a nasal irritant and a neurotoxin) contribute to the formation of urban ozone pollution. Ethylene glycol is listed in the 1990 Clean Air Act as a hazardous air pollutant and is on the EPA s Community Right-to-Know list. 

Thus, decomposition of PAN in the presence of NO can lead to the formation of OH radicals and conversion of NO to NOj merely from thermal reactions. This could be very important because PAN can be an indicator of the urban ozone-forming potential (see Section 8.4.1) and of the organic-oxidizing capacity of the urban air mass. The thermal decomposition of PAN also leads to the formation of NOj radicals. 

Chang S., McDonald-Buller E., Kimura Y., Yarwood G., Neece J., Russell M., Tanaka P., and Allen D. (2002) Sensitivity of urban ozone formation to chlorine emission estimates. Atmos. Environ. 36, 4991-5003. 

C. B., and Allen D. T. (2003) Direct evidence for chlorine-enhanced urban ozone formation in Houston, TX. Atmos. Environ. 37, 1393—1400. 

US Congress Office of Technology Assessment (1989) Catching Our Breath Next Steps for Reducing Urban Ozone. OTA-O-412, US Government Printing Office, Washington, DC. 

What levels of hydrocarbon and oxides of nitrogen emissions reductions are required to reduce urban ozone levels to desired standards ... 

Urban ozone and smog Urban ( 100 km) HC, NO, particulate matter... 

Atmospheric chemical transport models are evaluated by comparison of their predictions against ambient measurements. A variety of statistical measures of the agreement or disagreement between predicted and observed values can be used. Although raw statistical analysis may not reveal the cause of the discrepancy, it can offer valuable insights about the nature of the mismatch. Three different classes of performance measures have been used for urban ozone models. These tests are heavily weighted toward the ability of the model to reproduce the peak ozone concentrations and include ... 

Urban ozone formation potential is expressed relative to ethene. It represents the potential of an organic solvents vapor to form ozone relative to fliat of efliene ((g OJg sol-vent)/(g Os/g ethene)). Several groups of solvents, including alcohols, aldehydes, amines, aliphatic and aromatic hydrocarbons, esters, ethers, and ketones are active in ozone formation. Aldehydes, xylenes, some unsaturated compounds, and some terpenes are the most active among those. 

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