Houston High Ozone October 19, 2008

• Ozone Animation
• Plume Animation
• Back Trajectory Bayland Park CAMS 53 2pm
• Back Trajectory Bayland Park CAMS 53 3pm
• Back Trajectory Westhollow CAMS 410 3pm
• Back Trajectory Westhollow CAMS 410 4pm
• Satellite Image False Color - East Texas 2:48 am CDT (from UT CSR)
• Satellite Image False Color - East Texas 10:44 am CDT (from UT CSR)
• Satellite Image False Color - East Texas 3:10 pm CDT (from UT CSR)
• Satellite Image True Color - Houston 12:25 pm CDT (from UW SSEC)
• Satellite Image True Color - Houston 2:00 pm CDT (from UW SSEC)
• Winds Aloft at La Porte
• Winds Aloft at La Porte Mid-Day

High ozone was measured on the west and southwest side of the Houston area on Sunday, October 19th.   The highest measured eight-hour average was 85 parts per billion (ppb) at the Bayland Park Continuous Ambient Monitoring Station (CAMS) 53 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 102 parts per billion (ppb) for the hour from 2:00 to 3:00 p.m. Central Daylight Time (CDT), also at Bayland Park CAMS 53.    Level Orange ozone was measured at four sites, with "Moderate" or higher ozone at 18 sites out of 37 sites reporting complete data for the day.   This day was the 35th day with Level Orange or higher ozone measurements, based on the new ozone standard and AQI.   It was the 15th day with measured levels exceeding the old 8-hour ozone standard.

Skies were mostly clear all day. Winds were light from the northeast in the early morning and then shifted to the east in the late morning and to the southeast in the afternoon.   The high temperature was 78 degrees Fahrenheit (°F) at George Bush Houston Intercontinental Airport, 77°F at Hobby Airport, and 77°F at Galveston Airport.

Regional background levels of ozone coming into the Houston area were around 51 to 61 ppb as indicated by the peak eight-hour averages at Conroe CAMS 78, Kingwood CAMS 555, Crosby CAMS 553, Seabrook CAMS 45, Mustang Bayou CAMS 619, Lake Jackson CAMS 1016, and Danciger CAMS 618.    The difference of 24 to 34 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 28 to 40 percent of the measured 85 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 some of the highest ozone measurements.