Spatial Pattern of Ground-Level Ozone Concentration in Dallas-Fort Worth Metropolitan Area

Abstract

The objective of this study was to analyze spatial patterns of ground-level ozone concentration<br />in the Dallas-Fort Worth, Texas metropolitan area. Average daily maximum eight-hour ozone concentration,<br />number of days with concentrations exceeding 75 ppb, average outside air temperature, and resultant wind<br />direction at 20 monitoring stations were compiled for January-December, 2013. Recent estimates of population<br />and vehicle miles traveled were also compiled for 12 counties with ozone monitoring station(s). Ozone levels<br />and resultant wind directions were mapped for representative months in each season. On several days from<br />May-October, eight-hour ozone measurements exceeded 75 ppb. September, followed by August, produced<br />the highest ozone concentrations, as well as the most observations exceeding 75 ppb. Late spring and summer<br />months also showed the greatest range in ozone concentrations; during this time period, sustained southeasterly<br />winds caused distinct clusters of high ozone concentration at the northern perimeter of the study area.<br />However, ozone concentrations at individual monitoring stations were not associated with population or<br />vehicle miles traveled in counties occupied by those stations.