Phoenix, AZ compliance with the 1-hour and 8-hour ozone standards
- Arizona Dept. of Environmental Quality, Phoenix, AZ (United States)
The impending change from the 1-hour average ozone standard of 120 ppb to an 8-hour average standard of 80 ppb has far-reaching implications for attainment in Phoenix, Arizona. Based on hourly ozone data from 21 monitoring sites for April-September, 1996, both the severity and areal extent of ozone violations would increase dramatically with the 8-hour standard. Under the 1-hour standard, the monitoring site with the highest ozone concentrations exceeded the standard by 17%; under the 8-hour standard, the site with the highest 8-hour ozone average would exceed the standard by 39%. The area of ozone violations under the 1-hour standard was 1100 square kilometers in central and eastern metropolitan Phoenix. Under the 8-hour standard, this area of violation would expand 14 times to include virtually all of the metropolitan area and extend far into the desert and mountains northeast of the city. Predictions of 8-hour ozone concentrations, based on Urban Airshed Modeling of a July 22--24, 1996 episode, lead to more severe consequences than the 1996 measurements. The predicted 8-hour peak exceeded the 8-hour standard by a much larger margin than the predicted 1-hour peak: 70% versus 31% above standard. The change to the 8-hour standard will necessitate changes in the monitoring, modeling, and controlling of ozone. Additional monitoring sites east and north of the metropolitan area may have to be established to better determine the spatial variation of the high 8-hour ozone concentrations in this remote area. Biogenic emissions, which comprise the bulk of emissions in the remote country east and north of Phoenix, could play a more influential role. Compliance with this new standard will be more difficult, and present control strategies could prove less effective.
- OSTI ID:
- 361995
- Report Number(s):
- CONF-980632--
- Country of Publication:
- United States
- Language:
- English
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