Barrio Logan: Special Purpose Monitoring at Satellite Sites

This page last reviewed October 21, 2010

Special purpose monitoring for hexavalent chromium was conducted at satellite sites near the Memorial Academy School in Barrio Logan area.

The sampling for hexavalent chromium was conducted for 14 days total at six sampling locations during the month of December 2001. One of the sampling locations had collocated sampler and therefore, there were a total of 7 samplers. Within the14 sampling days, two were weekend days (Saturdays).

Of the 87 samples collected, 58 samples (67%) had values below the limit of detection (LOD). The LOD for hexavalent chromium is 0.2 nanograms per cubic meter (ng/m3). For this analysis, samples with values below the LOD were assumed the value of half LOD, which is 0.1 ng/m3.

Normally, concentrations of hexavalent chromium and some other toxic air pollutants are higher during winter than summer, due to stable meteorological conditions. The lowest measured concentration for seven samplers was 0.2 ng/m3. The highest measured concentration was 22 ng/m3. The average concentration for seven samplers (87 samples) was 0.98 ng/m3 with sampler average values ranging from 0.24 to 2.78 ng/m3.

Cancer risk is the number of potential excess cancer cases among a million people if the people are exposed to levels of a toxic air pollutant for 24 hours a day for 70 years. The table below shows the average concentrations of hexavalent chromium measured at the six sampling locations and the corresponding average potential cancer risk values. The cancer risk values shown in the table should not be viewed as annual average cancer risk values.

Sampling Location Average Hexavalent Chromium
Cancer Risk
(cases/ million)
Location 1 1.44 216
Location 2 0.37 55
Location 2c 0.38 57
Location 3 0.84 126
Location 4 0.62 93
Location 5 2.78 418
Location 6 0.24 36
Average (87 Samples) 0.98 147

For a complete data set, click here.