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Return to main Clark County MeteoStar Monitoring web page

Eight-Hour Ozone High Value Days for 2018
as of June 20

The table below lists the daily maximum eight-hour ozone concentrations measured which meet or exceed 71 parts per billion in 2018 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.

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YearSort ByReport Format
Highlight with AQI colors
2018 Sorted by Maximum Value
LocationRegionCAMSAQSDateTimeValuePOC
Green Valley 1 29832_003_0298June 19 201811:00771
Jerome Mack 1 54032_003_0540June 19 201812:00751
Walter Johnson 1 7132_003_0071June 8 201810:00741
Green Valley 1 29832_003_0298May 8 201810:00741
Indian Springs 1 777232_003_7772May 17 201811:00741
Jerome Mack 1 54032_003_0540May 8 201810:00731
Indian Springs 1 777232_003_7772June 8 201810:00731
Paul Meyer 1 4332_003_0043June 19 201810:00721
Walter Johnson 1 7132_003_0071May 29 201810:00721
Walter Johnson 1 7132_003_0071June 19 201810:00721
Jean 1 101932_003_1019June 1 201811:00721
Apex 1 2232_003_0022May 7 201809:00711
Paul Meyer 1 4332_003_0043June 8 201809:00711
Joe Neal 1 7532_003_0075June 8 201809:00711
Green Valley 1 29832_003_0298June 9 201808:00711
Jean 1 101932_003_1019June 8 201813:00711
POC (Parameter Occurrence Code): a code used to correctly separate data from multiple instruments at one site.

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.