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Daily Maximum Eight-Hour Ozone Averages for February 2021

The table below lists the peak daily maximum eight-hour ozone concentrations measured in February 2021 in each community where the DAQ measures ozone. Concentrations that are rated Moderate or higher are color-highlighted based on the EPA-defined Air Quality Index colors. (See Interpreting the AQI.) All ozone measurements are in parts per billion.

Use the selection boxes below to customize this report. You may select a different month, a different year, a different report format, and whether or not to include time on the report. Click on the Generate Report button once you have made your selections.

Month:Year:Report Format: Include time:
Include time
Highlight with AQI colors
AreaMonitoring SitePOCFebruary 2021POCMonitoring Site
123456789101112131415161718192021222324
Clark County
Virgin Valley1 N283139403741373438464044394137NV41434343414238231Virgin Valley
Paul Meyer1282844423640362932NV40404543364442413743414036181Paul Meyer
Mountains Edge1303243444242392930454241454435454442NV45433941291Mountains Edge
Walter Johnson13134504740444034384540424746424746443847454144271Walter Johnson
Palo Verde13334504640423936394441414545434645433946434044291Palo Verde
Joe Neal13031454340423936404439394342364343424045424039361Joe Neal
Green Valley13029414035393829294039414342344343423945413835121Green Valley
Jerome Mack122244138313532263136353640403341NV403742403729101Jerome Mack
Boulder City13332444238413946454540444443404444414245413941381Boulder City
Jean13335444441424050464241404444404544444547444139281Jean
POC (Parameter Occurrence Code): a code used to correctly separate data from multiple instruments at one site.
NV - There are not enough valid eight-hour averages for this day (there must be eighteen valid eight-hour averages).
 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.