The AirNow Map image above shows an increased concentration of ozone around the Maryland and D.C. region. At its maximum concentration, the air quality index reaches a Moderate level (51-100, Yellow).
The AirnowTech graph above supports this claim as ceilometer data from the D.C. region shows an ozone concentration that goes above 56 ppb between the hours of 12:00 and 19:00.
The Luft data from the NASA-supported branch of the Atmospheric Lidar Group‘s network supports this claim as there is a descending and mixing of ozone between the hours of 3:00 and 15:00 UTC.
Weather.gov supports this claim as it released an Air Quality warning for a large part of Maryland as well as D.C. due to the high levels of ground-level ozone in the area.