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Peak Daily One-Hour Ozone Averages for April 2018

The table below lists the peak daily one-hour ozone concentrations measured in April 2018 in each community where the Virginia DEQ measures ozone. Concentrations are color-highlighted based on the EPA-defined Air Quality Index colors. (See Interpreting the AQI.) All ozone measurements are in parts per billion, and are truncated to an integer number.

The values that go into this table are calculated at 3:30 am each morning. Therefore, the current day will almost always have very low hourly averages that are not truly representative of local conditions for the day. Because of this, the report does not display the current day's data.

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 using AQI colors
AreaMonitoring SitePOCApril 2018POCMonitoring Site
Rural Retreat15148524852555550434849586853523958641Rural Retreat
AreaMonitoring SitePOCApril 2018POCMonitoring Site
Albemarle High School14943404951605154445355627256473956581Albemarle High School
Frederick Co. Public School Maint. Dept.14444374747524648435348546562353541541Frederick Co. Public School Maint. Dept.
Natural Bridge Station14935384951594554465451607353494860661Natural Bridge Station
Harrisonburg VDOT14540394849554952425248566455453752531Harrisonburg VDOT
AreaMonitoring SitePOCApril 2018POCMonitoring Site
Blue Ridge
Herman L. Horn Elementary School14840364850574652444951587151434158661Herman L. Horn Elementary School
AreaMonitoring SitePOCApril 2018POCMonitoring Site
Charles City County14944415249624951525054576050335949521Charles City County
Beach Road VDOT15041395149604951484854586252366050551Beach Road VDOT
MSIC (MathScience Innovation Center)14943405550604852515154576152366150391MSIC (MathScience Innovation Center)
AreaMonitoring SitePOCApril 2018POCMonitoring Site
NASA Langley Research Center15047475251575149515356545647375450501NASA Langley Research Center
Tidewater Community College15144445348604953475054565849364950451Tidewater Community College
VA Tech Agricultural Research Center15546455351615053505156565748375350561VA Tech Agricultural Research Center
AreaMonitoring SitePOCApril 2018POCMonitoring Site
Aurora Hills Visitor Center14336384547584648445151586653445842521Aurora Hills Visitor Center
Fredericksburg Geomagnetic Observatory14841425550605254475655586853425546521Fredericksburg Geomagnetic Observatory
Lee District Park - Fairfax County14637394749585051465455596653435942541Lee District Park - Fairfax County
Sumerduck - C. Phelps Wildlife Mgmt Area14645405149595153445555616954453444521Sumerduck - C. Phelps Wildlife Mgmt Area
Ashburn - Broad Run High School14443384850584750425353596755443643521Ashburn - Broad Run High School
Shenandoah National Park - Big Meadows15244494849585252495549597160525253571Shenandoah National Park - Big Meadows
Long Park - Haymarket14542384849604752445555616858403650521Long Park - Haymarket
Widewater Elem. School - Widewater14740405251565254495555606954445742531Widewater Elem. School - Widewater

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.