Mobile Monitoring Data

Mobile Monitoring Data in Response to ExxonMobil Baytown Incident

HCPCS tested for volatile organic compounds (VOCs) and benzene using handheld monitors. Each data point reflects data collected at the time and location denoted. The most recent monitoring data is displayed by default. Click on the layers icon at the top-right of the map to view data for previous days.

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The benzene readings from monitor 1021 were due to a calibration drift resulting in false detections beginning at 8:30 PM on 8/2/19. This was confirmed by conducting a comparison reading in tandem with another monitor. PCS had used monitor 1021 prior to the detections to conduct a study of emissions during the fueling of a vehicle which showed positive readings benzene at concentrations of 0.125 ppm and 0.450 ppm, prior to and during fueling respectively. All readings outside of the facility remain at 0.000 ppm.

Baytown Exxon Incident UPDATE (August 3, 2019, 3:15 PM):

(Haga clic aquí para ver en español.)

Harris County Pollution Control (PCS), Harris County Fire Marshal (HCFMO), the Harris County Office of Homeland Security & Emergency Management and other county partners have been responding to the Exxon Baytown Olefins Plant fire since the morning of Wednesday, July 31st.

Based on extensive monitoring, responding county departments have determined that it is now safe to discontinue air monitoring. County air monitoring will cease at 3:00 p.m. on Saturday, August 3rd. The county will continue to coordinate with the Texas Commission of Environmental Quality (TCEQ), the Environmental Protection Agency, and Exxon during their ongoing air monitoring and will resume activities if conditions change.

PCS air monitoring has detected no trace of benzene in the areas outside the facility in the past 72 hours. Readings of .15 ppm were observed at the damaged stack in the plant on Friday. This was prior to the end of Exxon's liquid removal operations. At 5:30 Friday evening, HCFMO investigators entered the same location. Their air monitoring detected no benzene at any point while on-site, through 11:30 this morning.

An experiment by PCS performed at a local fuel station showed benzene levels of 0.125 ppm prior to pumping gas and 0.450 ppm while pumping gas (about 5 minutes). This is far below the OSHA standard for a gasoline fill-up of 5 ppm over 15 minutes. Sampling done in areas away from the station were at 0.0000 ppm. For comparison, the background readings of benzene at a gas station are less than the amount of .15 ppm recorded at the fire site early Friday afternoon.

Exxon issued the all-clear this morning at 8:00 a.m. and the facility reports that all liquid product has been removed from the impacted unit. They are resuming normal operations.

Exxon air monitoring continues to show benzene levels of less than 1 ppm to be isolated at the fire site. This has no impact to other areas of the facility or the community. Flaring may continue over the next one to two days but does not pose a public health risk. As a precaution, Exxon will continue air monitoring until that process is complete in coordination with TCEQ.

Harris County Fire Marshal investigators are conducting a thorough investigation and the Harris County Attorney has taken civil action against the facility to protect the interests of county residents.

Pollution Control Services Department