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Peak Daily One-Hour Ozone Averages for April 2019

The table below lists the peak daily one-hour ozone concentrations measured in April 2019 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 2019POCMonitoring Site
Rural Retreat1535561656052423951566348395246556055514835511Rural Retreat
AreaMonitoring SitePOCApril 2019POCMonitoring Site
Albemarle High School1504658615348434655574838452948525955424138481Albemarle High School
Frederick Co. Public School Maint. Dept.1484752533958434554524440493047514855464538491Frederick Co. Public School Maint. Dept.
Natural Bridge Station1495060595247404154575343454649536461434337481Natural Bridge Station
Harrisonburg VDOT1485056574550424253555046444849495758454437441Harrisonburg VDOT
AreaMonitoring SitePOCApril 2019POCMonitoring Site
Blue Ridge
Herman L. Horn Elementary School1505158615350374051576049434949526561434436511Herman L. Horn Elementary School
AreaMonitoring SitePOCApril 2019POCMonitoring Site
Charles City County1504359564741453845605145432752515952384438481Charles City County
Beach Road VDOT1504159604846443747575545462950515855424236461Beach Road VDOT
MSIC (MathScience Innovation Center)1504157604845463848585744482951506956414239481MSIC (MathScience Innovation Center)
AreaMonitoring SitePOCApril 2019POCMonitoring Site
NASA Langley Research Center1494755595545594050555152483153526059444542481NASA Langley Research Center
Tidewater Community College1464451524739563837474647412950515555414236471Tidewater Community College
VA Tech Agricultural Research Center1494755595044534342605451433153526057444636521VA Tech Agricultural Research Center
AreaMonitoring SitePOCApril 2019POCMonitoring Site
Aurora Hills Visitor Center1484455544556554656564247513245525458414743471Aurora Hills Visitor Center
Fredericksburg Geomagnetic Observatory1514859584852534453594645483047495956414440501Fredericksburg Geomagnetic Observatory
Lee District Park - Fairfax County1494857614657554657574548493043515757404544471Lee District Park - Fairfax County
Sumerduck - C. Phelps Wildlife Mgmt Area1484555584753404450584637442942486258414137461Sumerduck - C. Phelps Wildlife Mgmt Area
Ashburn - Broad Run High School1494355543955494657564237483149505655444441481Ashburn - Broad Run High School
Shenandoah National Park - Big Meadows1525157595553496258615150614954546358464740521Shenandoah National Park - Big Meadows
Long Park - Haymarket1504756584458484356564539493047515958454440501Long Park - Haymarket
Widewater Elem. School - Widewater1524859594757524755584740483044495956404240491Widewater 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.