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Eight-Hour Ozone High Value Days for 2018
as of August 21

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
Jean 1 101932_003_1019June 27 201810:00811
Joe Neal 1 7532_003_0075July 16 201811:00801
Paul Meyer 1 4332_003_0043August 6 201810:00791
Walter Johnson 1 7132_003_0071July 16 201810:00791
Joe Neal 1 7532_003_0075July 15 201810:00781
Green Valley 1 29832_003_0298June 27 201810:00781
Green Valley 1 29832_003_0298July 10 201810:00781
Green Valley 1 29832_003_0298July 14 201810:00781
Jerome Mack 1 54032_003_0540July 14 201809:00781
Indian Springs 1 777232_003_7772June 27 201809:00781
Walter Johnson 1 7132_003_0071July 17 201810:00771
Walter Johnson 1 7132_003_0071August 6 201810:00771
Green Valley 1 29832_003_0298June 19 201811:00771
Green Valley 1 29832_003_0298July 26 201810:00771
Jerome Mack 1 54032_003_0540July 26 201810:00771
Jean 1 101932_003_1019June 23 201811:00771
Paul Meyer 1 4332_003_0043July 23 201811:00761
Walter Johnson 1 7132_003_0071June 23 201811:00761
Walter Johnson 1 7132_003_0071June 27 201810:00761
Joe Neal 1 7532_003_0075July 27 201809:00761
Joe Neal 1 7532_003_0075August 6 201810:00761
Jerome Mack 1 54032_003_0540June 27 201810:00761
Paul Meyer 1 4332_003_0043June 27 201810:00751
Paul Meyer 1 4332_003_0043July 16 201811:00751
Walter Johnson 1 7132_003_0071July 26 201809:00751
Palo Verde 1 7332_003_0073July 16 201810:00751
Green Valley 1 29832_003_0298June 23 201812:00751
Jerome Mack 1 54032_003_0540June 19 201812:00751
Jerome Mack 1 54032_003_0540July 10 201810:00751
Indian Springs 1 777232_003_7772July 3 201809:00751
Apex 1 2232_003_0022June 27 201809:00741
Apex 1 2232_003_0022August 1 201810:00741
Apex 1 2232_003_0022August 6 201811:00741
Paul Meyer 1 4332_003_0043July 17 201809:00741
Walter Johnson 1 7132_003_0071June 8 201810:00741
Walter Johnson 1 7132_003_0071June 20 201811:00741
Walter Johnson 1 7132_003_0071June 30 201810:00741
Walter Johnson 1 7132_003_0071July 27 201809:00741
Walter Johnson 1 7132_003_0071August 7 201810:00741
Palo Verde 1 7332_003_0073July 17 201809:00741
Joe Neal 1 7532_003_0075August 7 201809:00741
Green Valley 1 29832_003_0298May 8 201810:00741
Green Valley 1 29832_003_0298July 23 201810:00741
Green Valley 1 29832_003_0298August 6 201810:00741
Indian Springs 1 777232_003_7772May 17 201811:00741
Apex 1 2232_003_0022July 10 201810:00731
Paul Meyer 1 4332_003_0043August 7 201809:00731
Walter Johnson 1 7132_003_0071July 10 201808:00731
Walter Johnson 1 7132_003_0071July 31 201810:00731
Joe Neal 1 7532_003_0075July 31 201810:00731
Joe Neal 1 7532_003_0075August 9 201810:00731
Green Valley 1 29832_003_0298July 15 201810:00731
Green Valley 1 29832_003_0298July 30 201809:00731
Jerome Mack 1 54032_003_0540May 8 201810:00731
Jerome Mack 1 54032_003_0540July 15 201810:00731
Jerome Mack 1 54032_003_0540July 16 201811:00731
Jerome Mack 1 54032_003_0540July 23 201810:00731
Jean 1 101932_003_1019June 26 201812:00731
Indian Springs 1 777232_003_7772June 8 201810:00731
Indian Springs 1 777232_003_7772June 23 201813:00731
Paul Meyer 1 4332_003_0043June 19 201810:00721
Paul Meyer 1 4332_003_0043June 23 201810:00721
Paul Meyer 1 4332_003_0043July 14 201809:00721
Paul Meyer 1 4332_003_0043July 22 201809:00721
Paul Meyer 1 4332_003_0043July 26 201809:00721
Paul Meyer 1 4332_003_0043July 27 201809:00721
Paul Meyer 1 4332_003_0043August 11 201811:00721
Walter Johnson 1 7132_003_0071May 29 201810:00721
Walter Johnson 1 7132_003_0071June 19 201810:00721
Walter Johnson 1 7132_003_0071July 3 201809:00721
Walter Johnson 1 7132_003_0071July 25 201809:00721
Walter Johnson 1 7132_003_0071August 3 201810:00721
Walter Johnson 1 7132_003_0071August 11 201810:00721
Palo Verde 1 7332_003_0073June 27 201810:00721
Palo Verde 1 7332_003_0073August 6 201810:00721
Joe Neal 1 7532_003_0075June 20 201811:00721
Joe Neal 1 7532_003_0075June 23 201810:00721
Joe Neal 1 7532_003_0075June 27 201810:00721
Green Valley 1 29832_003_0298June 22 201811:00721
Green Valley 1 29832_003_0298July 25 201810:00721
Green Valley 1 29832_003_0298August 1 201809:00721
Green Valley 1 29832_003_0298August 7 201810:00721
Jerome Mack 1 54032_003_0540June 23 201810:00721
Jerome Mack 1 54032_003_0540July 30 201810:00721
Boulder City 1 60132_003_0601June 27 201810:00721
Jean 1 101932_003_1019June 1 201811:00721
Jean 1 101932_003_1019August 11 201810:00721
Indian Springs 1 777232_003_7772June 25 201810:00721
Indian Springs 1 777232_003_7772June 26 201810:00721
Apex 1 2232_003_0022May 7 201809:00711
Apex 1 2232_003_0022July 26 201809:00711
Apex 1 2232_003_0022August 7 201810:00711
Apex 1 2232_003_0022August 12 201810:00711
Paul Meyer 1 4332_003_0043June 8 201809:00711
Paul Meyer 1 4332_003_0043June 20 201811:00711
Paul Meyer 1 4332_003_0043June 30 201810:00711
Paul Meyer 1 4332_003_0043July 25 201809:00711
Walter Johnson 1 7132_003_0071July 15 201809:00711
Walter Johnson 1 7132_003_0071July 22 201808:00711
Palo Verde 1 7332_003_0073June 23 201811:00711
Joe Neal 1 7532_003_0075June 8 201809:00711
Green Valley 1 29832_003_0298June 9 201808:00711
Green Valley 1 29832_003_0298July 3 201808:00711
Green Valley 1 29832_003_0298July 16 201811:00711
Green Valley 1 29832_003_0298August 11 201811:00711
Jerome Mack 1 54032_003_0540August 6 201810:00711
Jerome Mack 1 54032_003_0540August 7 201809:00711
Jean 1 101932_003_1019June 8 201813:00711
Jean 1 101932_003_1019July 3 201807:00711
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.