Assessing Outdoor Air Near Schools
Stevens Creek Elementary School - Cupertino, CA
Results and Analysis of EPA’s monitoring
EPA selected Stevens Creek Elementary School for monitoring because reports from recent monitoring studies have raised concerns about the potential for elevated levels of hexavalent chromium near cement plants. Stevens Creek Elementary School is approximately 1.5 miles from a cement plant and is also located near the route used by cement trucks carrying product from the cement plant.
|Primary Findings||During EPA’s monitoring period, levels of hexavalent chromium in the air at the school were below levels of concern for short-term and long-term exposure.|
|Pollutants Monitored||Hexavalent chromium. Inhalation of hexavalent chromium at high levels can damage the respiratory system and cause cancer.|
|Next Steps||EPA will not extend air toxics monitoring at Stevens Creek Elementary School at this time because levels of hexavalent chromium measured in the air at the school during the monitoring period were well below levels of concern for long-term exposure.
The Bay Area Air Quality Management District (BAAQMD) will continue to monitor hexavalent chromium at this location to collect a full year of monitoring data consistent with their monitoring policy. All hexavalent chromium monitoring results from EPA’s monitoring are available on the EPA website for this school; we will also post results from the additional BAAQMD monitoring as they become available.
BAAQMD will also be initiating a deposition/fallout study for several metals, and will be conducting mobile monitoring near this facility for a full suite of criteria pollutants. Results from these additional studies will be available through the BAAQMD website.
The Bay Area Air Quality Management District (BAAQMD) continues to oversee facilities in this area through several types of permits and voluntary programs. One of these permits, required by the Clean Air Act, outlines the legal emission control requirements industrial facilities must meet. The permit must be renewed every five years, with opportunity for public comment.
Summary of Study Approach and Findings
- A monitor collected air samples from June 30 through September 10, 2009 at the Stevens Creek Elementary School in Cupertino, CA. Hexavalent chromium was the pollutant of interest (“key pollutant”).
- We posted individual air sample results on this website throughout the monitoring period to keep your community informed during the monitoring period. We continue to provide air sample results from BAAQMD’s monitoring study at the school as the results become available.
- During the monitoring period, we evaluated the monitored concentrations to see if there was a concern from short-term exposures (e.g., several weeks).
- When the monitoring was complete, we analyzed the results to see if there was a concern from long-term exposures (over a lifetime).
- Also, when the monitoring was complete, we evaluated all the air samples from the on-site monitor. We also evaluated information on wind speed and wind direction from a weather monitor at the school, along with historical weather information and operations information from the nearby cement plant.
- Based on the individual monitoring results from the three-month sampling period, we found no concern for risk of health problems from short-term exposures to hexavalent chromium.
- Our analysis found that levels of hexavalent chromium in the air at the school are below levels of concern for long-term exposure.
- Our analysis indicates that hexavalent chromium concentrations in the air near the school do not appear to be influenced by a nearby industrial facility.
- The nearby cement plant was operating at less than full capacity during a portion of the monitoring period, with a key unit that normally emits into the air shut down for 3 of the 13 days on which sampling occurred. All units were operating on the remaining 10 days.
- The most recently available chromium emission estimates for the nearby facility from EPA’s Toxics Release Inventory for 2008 are lower than previously available estimates.
- Because the analysis shows hexavalent chromium levels are below levels of concern, EPA is not extending air toxics monitoring at Stevens Creek Elementary School; however the BAAQMD will conduct additional monitoring at this location until a full year of monitoring data is available consistent with their monitoring policy.
- Click here for additional information
How We Analyzed the Information We Collected at this School
The analysis considered whether the information collected at the school might raise concerns for the health of children or adults at the school. We looked at the following types of information:
- Measured hexavalent chromium concentrations
- Information on hexavalent chromium
- Measured wind direction and wind speed at the school
- Information about a potential nearby source of hexavalent chromium emissions
Analysis of Measured Hexavalent Chromium Concentrations:
Of the 13 samples taken, 3 were taken when the plant was not operating all of the main units that emit into the air. Of the 10 samples collected when all main units were operating, hexavalent chromium was not detected in 5 samples and was detected in very small amounts in the other 5 (ranging from 0.001 to 0.020 ng/m3). All these values are well below the long-term cancer-based comparison level of 8.3 ng/m3 and long-term noncancer-based comparison level of 100 ng/m3.
Result: The hexavalent chromium levels for the samples collected were well below the long-term comparison level. The health concern from hexavalent chromium at this site is low.
Analysis of Measured Wind Direction and Wind Speed at the School
We took measurements of wind direction and speed every day during the sample period. We took special note of the wind speed and direction on the days we took measurements of hexavalent chromium.
|What we looked at||What we found|
|We looked at whether the wind data taken on the days we took measurements of hexavalent chromium are similar or different from the wind patterns during the entire sampling period.||We found the wind patterns taken on the days we took measurements of hexavalent chromium to be generally similar to those observed during the sampling period.|
|We looked at whether the wind pattern during the sampling period is reflective of regional wind pattern over the long term.||Although we lack long term wind data at the monitoring station, we concluded that wind patterns over the sampling period were generally similar to the long-term patterns for the region. BAAQMD is continuing to collect wind data at this school to better characterize long-term wind patterns.|
Analysis of Information on Nearby Source of Hexavalent Chromium Emissions
|What we looked at||What we found|
|Whether we could determine if the source was operating as usual during the sampling period||The nearby cement plant was operating at less than full capacity during a portion of the monitoring period, with the cement kiln shut down for 3 of the 13 days on which sampling occurred. The kiln was operating on the remaining 10 sampling days. Operations on these days varied from close to full capacity to approximately 35% of capacity.|
|The nearby cement plant has an operating permit issued by the BAAQMD that includes operating requirements.|
Technical Report for School: Assessing Outdoor Air Near Schools: Stevens Creek Elementary School (Cupertino, CA) (PDF) (20pp, 135k). The technical report is geared toward risk assessors, risk managers, and other regulatory agencies.