Houston High Ozone September 29, 2008

• Ozone Animation
• Plume Animation - Regional
• Back Trajectory CAMS 1016 4:00 pm CDT
• Satellite Image - East Texas 3:57 am - False Color (from UT CSR)
• Satellite Image - East Texas 11:48 am - False Color (from UT CSR)
• Satellite Image - East Texas 2:21 pm - True Color (from UT CSR)
• Satellite Image - Texas 2:21 pm - True Color (from UW SSEC)
• Satellite Image - East Texas 3:18 pm - False Color (from UT CSR)
• Satellite Image - Texas 5:22 pm - False Color (from JHU APL)
• Satellite Image True Color - Houston 12:40 am CDT (from UW SSEC)
• Satellite Image True Color - Houston 2:21 pm CDT (from UW SSEC)

High ozone was measured on the south side of the Houston metro area on Monday, September 29th.   The highest measured eight-hour average was 86 parts per billion (ppb) at the Lake Jackson Continuous Ambient Monitoring Station (CAMS) 1016 and rated as Level Orange, Unhealthy for Sensitive Groups, on the U.S. Environmental Protection Agency (EPA) Air Quality Index (AQI) scale.    The highest measured one-hour average was 101 parts per billion (ppb) for the hour from 3:00 to 4:00 p.m. Central Daylight Time (CDT), also at Lake Jackson CAMS 1016. Level Orange ozone was measured at three sites, with "Moderate" or higher ozone at 19 sites out of 37 sites reporting complete data for the day.   This day was the 30th day with Level Orange or higher ozone measurements, based on the new ozone standard and AQI.   It was the 11th day with measured levels exceeding the old 8-hour ozone standard.

Skies were mostly clear all day.    Winds were light from the north to northwest in the early morning and then shifted to the north to northeast in the late morning. Along the immediate coast, winds shifted to the east to southeast with the sea breeze in the late afternoon.    The high temperature was 88 degrees Fahrenheit (°F) at George Bush Houston Intercontinental Airport, and 87°F at Hobby Airport.   The Galveston Airport weather station was still down after Hurricane Ike.

Regional background levels of ozone coming into the Houston area were around 51 to 54 ppb as indicated by the peak eight-hour averages at Conroe CAMS 78, Kingwood CAMS 555, and Crosby CAMS 553.    The difference of 32 to 35 ppb between the measured eight-hour area maximum and the approximate regional background level was likely caused by local air pollution sources in the Houston area.    The approximate local contribution was about 37 to 41 percent of the measured 86 ppb area eight-hour peak.

The Plume Animation - Regional 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 some of the highest ozone measurements.