Houston High Ozone
September 1, 2006

Images

• Ozone Animation
• Plume Animation
• Plume Animation - Regional
• Satellite Animation
• Satellite Image - Houston 12:37 p.m. - True Color (from UT CSR)
• Satellite Image - Houston 2:18 p.m. - True Color (from UT CSR)
• Winds Aloft at La Porte Airport
• Winds Aloft at La Porte Airport Mid-day
• Ozone, NOx, HRVOC Graphs

Description

High ozone was measured over much of the Houston area on Friday, September 1st. The highest measured eight-hour average was 129 parts per billion (ppb) at the Houston Regional Monitoring (HRM) Site 8 in La Porte and rated as Level Purple, Very Unhealthy, on the U.S. Environmental Protection Agency (EPA) Air Quality Index (AQI) scale. The highest measured one-hour average was 161 parts per billion (ppb) for the hour from 4:00 to 5:00 p.m. Central Daylight Time (CDT) at Haden Road CAMS 603. AQI Level Purple was measured at only one site, AQI Level Red or higher was measured at nine sites, AQI Level Orange or higher ozone was measured at 32 sites, and AQI "Moderate" or higher ozone was measured at 42 sites out of 44 sites reporting complete ozone data for the day. This day was the 32nd day this year with Level Orange or higher ozone measurements, the 12th day with Level Red or higher measurements, and the second day with Level Purple measurements somewhere in the Houston area.

Skies were clear in the early morning, becoming partly cloudy in the late morning and afternoon. Winds were light from the west-northwest in the early morning, becoming light from the east mid-day with the bay breeze and then moderate from the southeast in the late afternoon and evening with the sea breeze. The high temperature was 96 degrees Fahrenheit (°F) at George Bush Houston Intercontinental Airport, 92°F at Hobby Airport, and 91°F at Galveston Airport.

Regional background levels of ozone, in the air coming into the Houston area, were at least about 63 to 66 ppb as indicated by the peak eight-hour averages at Danciger CAMS 618, Lake Jackson CAMS 1016, and Mustang Bayou CAMS 619. The difference of 55 ppb between the measured eight-hour area maximum of 121 ppb and the approximate regional background level of 66 ppb was likely caused by local air pollution sources in the Houston area. The estimated 55 ppb local contribution was 45 percent of the measured 121 ppb area eight-hour peak.

The Plume Animation shows the estimated plume tracks from large industrial sources of oxides of nitrogen (NOx) and volatile organic compounds (VOC), along with the plume tracks for the centers of the broad urban plumes coming from downtown Houston and other major urban centers. The plume animation suggests that urban and industrial emissions from the Houston Ship Channel area were in the vicinity of the highest ozone measurements.