FREQUENTLY ASKED QUESTIONS
INITIAL SAMPLE RESULTS
EPA SCHOOLS MONITORING INITIATIVE
STEVENS CREEK ELEMENTARY SCHOOL
SUMMARY: On August 4, 2009 EPA posted the first preliminary set of air toxics monitoring data, representing
the first two samples taken, for Stevens Creek Elementary School in Cupertino, CA. For more information, see
EPA's website at: http://www.epa.gov/region09/air/schools-monitor/stevens-creek.html.
CONTENT:
Questions 1-10 answer general questions about the monitoring at Stevens Creek Elementary School and
the preliminary results from the first two samples.
1. When did monitoring begin?
2. When will the next results be available?
3. When will the full set of results be available?
4. What do the current results show?
5. Was the cement plant operating on the days the air samples were taken?
6. Why did you sample when the kiln was not operating?
7. Was the wind blowing from the facility to the school on the days the air samples were taken?
8. How does the detection limit compare to health values, including California's?
9. You have the wrong location - why don't you move the monitor to another school?
10. Why aren't you monitoring for mercury?
Questions 11-15 answer more detailed questions about data validity for the National School Monitoring
Initiative.
11. How do you know the monitor is not being tampered with?
12. How do you know the results are valid?
13. What is the likelihood of a false negative?
14. What types of controls were used in the lab?
What if I have more questions?
If your question or concern was not fully answered by this Q and A document, you may visit our regional
website at: http://www.epa.gov/region09/air/schools-monitor or our national website at:
http://www.epa.gov/schoolair/. You may also want to review a fact sheet developed for the monitoring initiative
at Stevens Creek Elementary School, available here: http://www.epa.gov/region09/air/schools-monitor/stevens-
creek.html.
You may also call Kathleen Stewart, Staff Air Quality Risk Assessor with the EPA, Region 9 office in San
Francisco at (415) 947-4119, or email us at r9schoolmonitoring@epa.gov.
Press questions should be directed to Francisco Arcaute with the EPA, Region 9 Office of Public Affairs at (213)
244-1815.
-------
1. When did monitoring begin?
Monitoring at Stevens Creek Elementary School began at the end of June. Because we do not want to
disclose the monitoring schedule prior to the end of the monitoring study, we will not be revealing
sampling dates until the end of the study period.
2. When will the next results be available?
We will be posting results periodically, approximately every other week. We generally post data on
Tuesdays, providing the data have gone through quality assurance checks.
3. When will the full set of results be available?
We anticipate that monitoring will be complete by early September. We anticipate that results from the
final set of samples will be available in late September. As soon as possible after monitoring is
completed, EPA will perform an analysis of the results and make it available to the public through our
web site.
4. What do the current results show?
No hexavalent chromium was detected in the first two samples, even though the monitor can detect very
small amounts. EPA scientists caution that no conclusions can be drawn from these results until all
samples have been taken and analyzed along with important information about wind patterns and plant
operations on the days samples were taken. Once monitoring is complete at Stevens Creek Elementary
School, the full set of results will be analyzed to evaluate the potential for health concerns related to
short-term and long-term exposure to hexavalent chromium.
5. Was the cement plant operating on the days the air samples were taken?
On the day the first sample was taken, the cement kiln was not operating. Once the monitoring period is
complete we will provide as much information as possible to the community about the results, including
any information we have on facility operations, wind patterns, and other relevant information. We are
working closely with the Bay Area Air Quality Management District to gather this information, but we
welcome observations from the community at any time as well.
6. Why did you sample when the kiln was not operating?
The first sample at Stevens Creek Elementary School is a special, extra sample that is in addition to the
routine 60 days of sampling established for EPA's School Monitoring Initiative. We felt it would be
valuable to sample air at Stevens Creek Elementary School while the kiln was not operating to
understand how the kiln might affect the monitoring results.
7. Was the wind blowing from the facility to the school on the days the air samples were taken?
Once the full set of air samples has been collected, EPA will analyze the results to estimate long-term
average levels of hexavalent chromium at the school. We will use that information to determine whether
these levels are a health concern for school-age children, school staff, and the local community exposed
over many years. As part of that analysis we will evaluate information on wind direction and speed.
Because we do not want to disclose any information that might hint at the monitoring schedule until the
study is complete, we will not be releasing information about wind patterns on the days samples were
taken until the end of the study period.
8. How does the detection limit compare to health values, including Calfornia's?
Detection limits for EPA's School Monitoring Initiative have been established and are described in the
School Air Toxics Ambient Monitoring Plan, available at:
http://www.epa.gov/ttn/amtic/files/ambient/airtox/2009sat/SATMonitoringPlan.pdf
Detection limits for all chemicals being monitored by EPA under this initiative are low enough to enable
health-based decision making. The detection limit established for hexavalent chromium allows for
detection of concentrations of hexavalent chromium well below the health values established by both the
U.S. Environmental Protection Agency and the California Environmental Protection Agency.
-------
9. You have the wrong location - why don't you move the monitor to another school?
The original site was chosen as a starting point based on distance from the facility, an analysis of wind
direction during the summer months, and the school's proximity to the route used by trucks entering and
exiting the cement plant. Once the full set of initial air samples has been collected we will analyze the
results, including information on wind patterns and facility operations, to determine if further monitoring
is needed.
10. Why aren't you monitoring for mercury?
Mercury, like hexavalent chromium, is a naturally occurring metal that can be present in both the raw
materials and the fuel used in cement manufacturing. EPA has recently proposed a rule to control and
monitor emissions of mercury and other hazardous air pollutants from cement plants that the public may
comment on. Several residents have asked EPA to consider monitoring for mercury as part of this
initiative. EPA and the Bay Area Air Quality Management District are analyzing recent monitoring data
to identify if additional monitoring in the area is needed at this time.
11. How do you know the monitor is not being tampered with?
All monitors are inaccessible either by location (e.g., on a school roof with restricted access) or by
security measures (e.g., within a secure enclosure, video surveillance). Also, an elapsed sample time
indicator is included on all samplers used in the school monitoring initiative. Any sample with a duration
outside the predetermined, method-specific value is noted on the chain-of-custody form. The sample will
be flagged for further evaluation to determine if the results are invalid. Note that all sample retrievals
and documentation (i.e., shipping and handling, receipt at the analytical laboratory) and analyses follow
extensively developed and strictly enforced protocols. From the time sample media are prepared at the
laboratory until the time they're received back at the laboratory and analyzed, the chain of custody is
known and verifiable. Protocols for each and every phase of the sampling and analysis are established
and followed.
12. How do you know the results are valid?
To ensure validity of data, a process known as verification and validation is performed. Data validation
is not just done at the end of the process, but is built into the entire process from start to finish. For
details on how verification and validation is performed both in the lab and in the field, please refer to the
SAT Quality Assurance Project Plan (QAPP) at: http://www.epa.gov/ttn/amtic/airtoxschool.html.
Here is a brief explanation on how verification and validation is performed.
1. Before being shipped to the monitoring site, all collection media (canisters, filters etc) are
inspected in the laboratory.
2. All collection media are shipped to the monitoring site in a manner that does not allow
contamination.
3. Station operators follow the Standard Operating Procedures (SOPs), this includes the careful
handling of all collection media and noting any deviations from standard protocols. Chain of
Custody forms are filled out in ink and shipped with the media until arrival at the lab.
4. Laboratory staff handle all materials according to lab protocols and SOPs. SOPs are followed
closely in the preparation, extraction and analysis.
5. At the monitoring site, technicians collect two sets of samples (called co-located samples). Both
samples are treated in the same manner throughout the sampling, analytical and verification and
validation processes. The samples are compared against each other. The EPA has specific tests
that are run on collocated data. If the samples do not meet the Measurement Quality Objectives
as stated in Section 6 of the QAPP, then further investigation is performed.
6. Samples are placed in analytical instruments which detect the compound and provide a read-out
of its concentration. Instruments are carefully calibrated according to strict standards.
7. Once the samples have been analyzed, they are reviewed by senior staff at the laboratory. Any
values that might appear to be an outlier (i.e., unusually high or low) are then investigated
further.
-------
8. Data are transferred to EPA scientists who review the data and compare this data to the
meteorological conditions. Wind speed, direction, temperature are compared and the data are
graphed.
9. The data are then compared against risk driver screening levels.
13. What is the likelihood of a false negative?
The analytical instruments used here are very sensitive and the extraction techniques have been refined
to the point that false negatives are not very likely. However, false negatives can occur when the data
are so low in concentration that they are at or below the method detection limit (MDL) of the analysis.
It is possible that a compound may be present, but the instrumentation may not be able to detect it if
compound's concentration is extremely low. To minimize this problem, EPA employs laboratories with
instruments that have extremely low sensitivity and that use the most advanced analytical techniques. In
addition, EPA's contract laboratory continually works to lower their MDLs so as to maximize their
ability to detect extremely low concentrations.
14. What types of controls were used in the lab?
Here is synopsis of how controls are employed.
1. The EPA contract laboratory uses the accepted methods that have been refined over many years.
For instance, for Volatile Organic Compounds the EPA contract laboratory uses the EPA
developed technique known as Toxics Organic method 15. This method can be obtained on the
EPA's website: http://www.epa.gov/ttn/amtic/airtox.html. Where possible, the laboratory uses
the accepted EPA methods. For the dissocyanates and the 4,4 methylene dianaline,
Occupational Safety and Health Organization (OSHA) and National Institute for Occupational
Safety and Health (NIOSH) accepted methods are utilized.
2. Although the technique is followed closely, the laboratory modifies the technique in order to
maximize and lower levels of detection. The laboratory has a Quality Assurance Project Plan
and Standard Operating Procedures, which reflect the laboratory's practices. EPA scientists then
review the QAPP and SOPs annually to assure that the development of the laboratory's
techniques are in line with the objectives.
3. The laboratory purchases standard materials that are of the highest quality and purity. These
standards must be traceable to the National Institute of Standards and Technology (NIST),
which are recognized both in the US and the entire world as the best standards available. These
standard materials are then introduced into the analytical instruments and the instruments are
then adjusted and tuned to the standard materials. After this process of calibration and tuning,
the environmental samples are introduced and analyzed.
4. The data are reviewed by senior laboratory staff to ascertain that all protocols and Standard
Operating Procedures are followed.
5. EPA has purchased from an independent laboratory proficiency testing samples. These
proficiency testing samples are what are known as single blind samples. The proficiency testing
samples are created under strict guidelines. Then the independent lab sends these samples to the
EPA contract laboratories. The contract laboratories know these are proficiency testing samples,
but do not know the concentration. The results of the proficiency testing samples are compared
against the known concentration and the response must be within 30% of the known
concentration. It that is not the case, the contract laboratories must make the corrective action to
fix the problems. For this program, 3 proficiency testing samples will be used: at the beginning,
in the middle and towards the end of the project.
6. The contract laboratories are accredited by an independent audit body known as The NELAC
Institute. NELAC stands for the National Environmental Laboratory Accreditation Counsel.
This is an independent body consisting of State, local and private laboratories that perform
technical system audits and produce proficiency testing samples for their members. EPA is
involved in NELAC and supports their efforts.
------- |