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Daily Maximum Eight-Hour Ozone Averages for April 2019

The table below lists the peak daily maximum eight-hour ozone concentrations measured in April 2019 in each community where the Virginia DEQ 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 SitePOCApril 2019POCMonitoring Site
Rural Retreat148525861524938364854544036444553575345333447NA1Rural Retreat
AreaMonitoring SitePOCApril 2019POCMonitoring Site
Albemarle High School147445658434239434955443644404649575335393645NA1Albemarle High School
Frederick Co. Public School Maint. Dept.145455051354840415049393443364048445139423444NA1Frederick Co. Public School Maint. Dept.
Natural Bridge Station147485857434537375256504037414651595540393342NA1Natural Bridge Station
Harrisonburg VDOT145475552424439355053474241424245535437423441NA1Harrisonburg VDOT
AreaMonitoring SitePOCApril 2019POCMonitoring Site
Blue Ridge
Herman L. Horn Elementary School147485759464633365055544337414650605639383447NA1Herman L. Horn Elementary School
AreaMonitoring SitePOCApril 2019POCMonitoring Site
Charles City County147415554433740354055474240294949554734403444NA1Charles City County
Beach Road VDOT148365655403941354355513943334849565234403442NA1Beach Road VDOT
MSIC (MathScience Innovation Center)147385457413943354256523843304748635234403744NA1MSIC (MathScience Innovation Center)
AreaMonitoring SitePOCApril 2019POCMonitoring Site
NASA Langley Research Center147465356534155374353475039305050565440433944NA1NASA Langley Research Center
Tidewater Community College143424847413251363443424633274848495237393442NA1Tidewater Community College
VA Tech Agricultural Research Center146445257434049403955495035324950575340443447NA1VA Tech Agricultural Research Center
AreaMonitoring SitePOCApril 2019POCMonitoring Site
Aurora Hills Visitor Center145415348365050415253384347334149NVNV36444043NA1Aurora Hills Visitor Center
Fredericksburg Geomagnetic Observatory14745565643434941475643404532454856NV36423646NA1Fredericksburg Geomagnetic Observatory
Lee District Park - Fairfax County1NV45545440525042NV54434146314149525536434143NA1Lee District Park - Fairfax County
Sumerduck - C. Phelps Wildlife Mgmt Area14642525540443938455343NV41324047565337393544NA1Sumerduck - C. Phelps Wildlife Mgmt Area
Ashburn - Broad Run High School1474153533450464353543933453543NV525337423844NA1Ashburn - Broad Run High School
Shenandoah National Park - Big Meadows150505558524946555458494849454553605644443953NA1Shenandoah National Park - Big Meadows
Long Park - Haymarket148445456415043385254423446384348545438423845NA1Long Park - Haymarket
Widewater Elem. School - Widewater148445657434949424855453746304247555436413845NA1Widewater Elem. School - Widewater
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).
NA - Data not available.

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 Not Defined
401 - 500 0.505 - 0.604 Not Defined
500+ Not Defined Not Defined

PLEASE NOTE: This data has not been verified by the Virginia DEQ 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 Virginia DEQ 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.