8-hour Ozone Design Value is a statistic that describes the air quality status of a given location relative to the National Ambient Air Quality Standards (NAAQS). EPA ozone standard is an 8-hour average of 0.08 parts per million by volume [ppm(v)]. This standard is subdivided into primary standards that protect public health and secondary standards that protect public welfare (the numeric value of the standard is the same for primary and secondary standards). Areas in the United States where ozone levels measured in the ambient air exceed the 8-hour standard of 0.08 ppm(v) are said to be in nonattainment of this standard. A community meets the eight-hour standard when the three year average of the annual fourth highest daily maximum eight-hour ozone concentration measured at each montitoring site is less than 71 parts per billion (ppb).
For more information visit: http://www.nctcog.org/trans/air/ozone/
TCEQ, 2015 http://www.tceq.state.tx.us/cgi-bin/compliance/monops/8hr_attainment.pl;
*Please note that the 2015 data has not been verified by TCEQ and may change.