Torrance Air: Benzene Investigation Update
Overall, benzene readings from the monitor at West High have been higher than the data collected at North Torrance High School and Elm Ave. As part of South Coast AQMD's efforts to evaluate instruments and benzene levels within the Torrance Air network, South Coast AQMD has:
Conducted mobile monitoring to compare levels of benzene at the three monitoring sites;
Collected canister “grab” samples at both the West High and North High monitors for comparison;
Recently deployed additional stationary monitors to measure and compare benzene levels at the West High Station;
Collected additional samples during the late night and early morning hours at the West High station; and
Inspected the West High monitor calibration setup and performed minor maintenance.
Data from the mobile monitoring was generally lower than what was reported on the West High station. Additionally, the results from both the quick grab canister samples and the stationary monitor near the West High Station showed levels of benzene to be four times lower than what was reported on the Torrance Air website.
Three late evening samples (between 11 p.m. and 5 a.m.) were collected on different days. Laboratory results for these samples also showed benzene levels were two to four times lower than average data reported from the West High Monitor during those hours.
On January 17, South Coast AQMD conducted an inspection of the West High monitor and performed some standard maintenance which resulted in levels of benzene showing more similar results to the North High and Elm Ave. monitors as well as South Coast AQMD’s stationary monitors.
Based on data and analysis from South Coast AQMD’s independent monitoring and investigation, benzene levels reported at the West High Monitor prior to January 17th may have been affected by a calibration issue. South Coast AQMD is continuing to investigate the high reading of 15.24 ppb on January 16th.
South Coast AQMD is working with the contractor responsible for the monitors to collect more additional data to better validate the performance of the West High monitor. South Coast AQMD continues to conduct independent checks on the monitors, and the contractor has upgraded parts on all three monitors and added another monitor at the West High location for comparison based on our initial observations.