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Eight-Hour Ozone High Value Days for 2017
as of June 22

The table below lists the daily maximum eight-hour ozone concentrations measured which meet or exceed 71 parts per billion in 2017 in each community where the DAQ measures ozone. This information is updated hourly. Concentrations are color-highlighted based on the EPA-defined Air Quality Index colors. (See Interpreting the AQI.) Times shown are in 24-hour format and are Local Standard Time. Our convention is that the time reflects the beginning of the eight-hour average. All ozone measurements are in parts per billion.

Use the selection boxes below to customize this report. You may select a different year, a different sorting order, or a different report format. Click on the Generate Report button once you have made your selections.

YearSort ByReport Format
Highlight with AQI colors
2017 Sorted by Maximum Value
Joe Neal 1 7532_003_0075June 22 201709:00771
Palo Verde 1 7332_003_0073June 16 201709:00751
Joe Neal 1 7532_003_0075June 16 201710:00741
Arden Peak 1 777832_003_7778June 21 201723:00744 N
Walter Johnson 1 7132_003_0071June 16 201710:00731
Walter Johnson 1 7132_003_0071June 22 201709:00731
Palo Verde 1 7332_003_0073June 22 201708:00731
Joe Neal 1 7532_003_0075June 14 201711:00731
Arden Peak 1 777832_003_7778June 22 201701:00734 N
Walter Johnson 1 7132_003_0071June 17 201709:00721
Joe Neal 1 7532_003_0075June 17 201709:00721
Green Valley 1 29832_003_0298June 17 201709:00721
Walter Johnson 1 7132_003_0071May 23 201711:00711
JD Smith 1 200232_003_2002June 16 201710:00711
POC (Parameter Occurrence Code): a code used to correctly separate data from multiple instruments at one site.
 N - Data from this instrument does not meet EPA quality assurance criteria and cannot be used for regulatory purposes.

Interpreting the AQI

Air Quality Index

Each NAAQS pollutant has a separate AQI scale, with an AQI rating of 100 corresponding to the concentration of the Federal Standard for that pollutant. Additional information about the AQI and how it can be used is available from the EPA's AirNow web site.

Place your mouse pointer over the scale displayed above to view information about the Air Quality Index, and each of the rating levels.

The actual index calculation is different for each parameter measured and is specified by the EPA. The following table shows the various breakpoints used in calculating the AQI.

AQI Breakpoint Definitions
AQI Range 1hr Ozone
in ppm
8hr Ozone
in ppm
0 - 50 Not Defined 0 - 0.054
51 - 100 Not Defined 0.055 - 0.070
101 - 150 0.125 - 0.164 0.071 - 0.085
151 - 200 0.165 - 0.204 0.086 - 0.105
201 - 300 0.205 - 0.404 0.106 - 0.200
301 - 400 0.405 - 0.504 0.201 - 0.2011
401 - 500 0.505 - 0.604 Not Defined
500+ Not Defined Not Defined

PLEASE NOTE: This data has not been verified by the Clark County Department of Air Quality and may change. This is the most current data, but it is not official until it has been certified by our technical staff. Data is collected from Clark County Department of Air Quality ambient monitoring sites and may include data collected by other outside agencies. This data is updated hourly. All times shown are in local standard time unless otherwise indicated.