Dallas-Fort Worth High Ozone August 4, 2008

• Ozone Animation
• Plume Animation
• Plume Animation - Regional
• Satellite Animation
• Satellite Image False Color - Texas East 11:47 am CDT (from UT CSR)
• Satellite Image True Color - Texas East 11:55 am CDT (from UT CSR)
• Satellite Image False Color - Texas East 3:00 pm CDT (from UT CSR)
• Satellite Image True Color - Texas East 3:09 pm CDT (from UT CSR)
• Winds Aloft at Palestine
• Winds Aloft at Palestine Mid-Day

High ozone was measured in the Dallas-Fort Worth area on Monday, August 4th.    The highest measured eight-hour ozone average was 98 parts per billion (ppb) at the Eagle Mountain Lake Continuous Ambient Monitoring Station (CAMS) 75.    This measurement rated as Level Red, Unhealthy, on the U.S. Environmental Protection Agency (EPA) Air Quality Index (AQI) scale.   The highest one-hour ozone measurement was 109 ppb from 6:00 to 7:00 p.m Central Daylight Time (CDT) also at Eagle Mountain Lake CAMS 75.    Only one site measured Level Red ozone and seven sites measured AQI Level Orange or higher and exceeded the eight-hour ozone standard.   A total of 17 sites reported complete ozone data for the day. Moderate or higher ozone levels were reported at all 16 sites.    This was the first day this year with a AQI Level Red measurement and the 12th day this year with AQI Level Orange measurement somewhere in the Dallas-Fort Worth area based on the new ozone standard and the seventh day with measurements exceeding the old ozone standard.

Skies were clear all day. Winds were light and variable early and light from the east to southeast by late morning.   The high temperature reached 105 degrees Fahrenheit (°F) at the Dallas-Fort Worth Airport, 103°F at Dallas Love Field, and 103°F at Fort Worth Meacham Field.

Regional background levels of ozone ranged from about 69 to 80 ppb as indicated by peak eight-hour ozone measurements at Greenville CAMS 1006, Kaufman CAMS 71, Italy CAMS 1044, and Cleburne CAMS 77.   The difference of about 18 to 29 ppb between the measured eight-hour area maximum of 98 ppb and the approximate regional background level was likely caused by local air pollution sources in the Dallas-Fort Worth area.   The estimated local contribution was about 18 to 30 percent of the measured 98 ppb area eight-hour peak.

The Plume Animation shows the estimated plume tracks from large industrial sources of oxides of nitrogen (NOx) and/or volatile organic compounds (VOC), as well as plume tracks for the center of the broad urban plumes coming from Downtown Dallas, Downtown Fort Worth, and other major urban centers.   The plume animation suggests that urban and industrial emissions from the Dallas area were in the vicinity of the highest ozone measurements.