At a Glance: Management Alert: Certain State, Local and Tribal Data Processing Practices Could Impact Suitability of Data for 8-Hour Ozone Air Quality Determinations


•	• U.S. Environmental Protection Agency	17-P-0106
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At a Glance
Why We Did This Review
In the process of evaluating
whether selected ozone air
monitoring data meet the
criteria established by the
U.S. Environmental
Protection Agency (EPA), we
found two state monitoring
agencies that do not use
EPA-recommended data
processing practices. We are
issuing this report to alert the
EPA about these issues
before the agency starts
using the data to determine
whether air quality meets the
National Ambient Air Quality
Standard (NAAQS) for
ozone.
The EPA uses Air Quality
System (AQS) data to
determine whether an area's
air quality meets the NAAQS.
A nonattainment designation
means that an area's air
contains unhealthy levels of
pollution, and the state must
develop a plan to identify
enforceable measures to
improve air quality in that
area. The EPA plans to
designate areas for the new
ozone NAAQS in 2017.
This report addresses the
following EPA goal or
cross-agency strategy:
• Addressing climate
change and improving
air quality.
Send all inquiries to our public
affairs office at (202) 566-2391
or visit www.epa.gov/oia.
Listing of OIG reports.
Management Alert: Certain State, Local and Tribal Data
Processing Practices Could Impact Suitability of Data for
8-Hour Ozone Air Quality Determinations
There is a risk that multiple
air-monitoring agencies are not
always implementing the EPA's
recommended quality assurance
practices for ozone data. This
could lessen the quality of data
the agency uses to determine and
inform the public as to whether
the air is healthy to breathe.
What We Found
Air monitoring data the EPA received from
Georgia and South Carolina were not always
processed according to recommended
practices in the EPA's 2013 Quality
Assurance Handbook for Air Pollution
Measurement Systems (Quality Assurance
Handbook). Georgia and South Carolina
adjusted ozone data based on the results of
quality control checks known as "zero
checks" before reporting the data to the
AQS. According to the Quality Assurance Handbook, zero check adjustments,
although an accepted practice under certain conditions, should not be necessary
and may lead to more data quality uncertainty. While Georgia stopped adjusting its
data in 2015, South Carolina continued the practice.
Georgia and South Carolina were not implementing critical criteria as
recommended in Appendix D of the Quality Assurance Handbook. In Appendix D,
the EPA establishes three critical quality control checks ("zero," "one-point quality
control," and "span checks") to validate data. Georgia uses the three quality control
checks to validate its data, but the acceptance criteria that the state uses for these
checks are less stringent than what the EPA recommends. South Carolina does
not use zero checks to validate ozone data. South Carolina applies the one-point
quality control check to validate ozone data, but its acceptance criteria are less
stringent than the EPA's recommended critical criteria. South Carolina conducts
span checks, but does not follow EPA-recommended practices. Variation in the
use of acceptance criteria and critical quality control checks can impact the
integrity of data the EPA uses to make designation decisions.
We analyzed 2012-2014 ozone data across the country and determined that
about 26 percent of the hourly data reported in real time were different than
corresponding data reported to the AQS. While not all of the differences are
indicative of data adjustment practices, there is a risk that other air-monitoring
agencies are improperly adjusting their data before reporting it to the AQS. These
adjustments could impact the quality of data the EPA plans to use to determine
whether ozone levels present an adverse health risk to the public (i.e., the
designation process). Designation determinations can have significant implications
for public health and an area's economy. Therefore, it is important that the EPA
has assurance that its designation decisions are based on data that has
undergone a known, consistent and accepted quality control process.
Pending completion of our ongoing work, we are making no recommendations. We
are alerting the EPA to a potential risk in the use of ozone data for its designations
in 2017, so that the agency can take steps to further assess and mitigate risks as
needed. The agency has initiated actions to assess these risks.

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