Ozone photochemistry trends in the Houston Ship Channel

Due to transportation and industry dominating Houston's economy, local air quality is in non-compliance according to EPA NAAQS. Policy-makers and industries have worked together to decrease the reactive hydrocarbon and NOx emissions in order to bring the area into attainment of the ozone NAAQS. These emission reductions were designed to reduce ozone, and should have substantially affected the photochemical environment. This study examines these possible changes in the photochemical environment in the Houston Ship Channel since 2000, where the combination of combustion processes and hydrocarbon emissions still cause high ozone events.

Hydrocarbon, trace gas, and meteorology data are input into the Langley Research Center (LaRC) photochemical box model to study trends in photochemistry since the turn of the century. Emphasis is given on ozone formation mechanisms and efficiency, speciated hydrocarbon reactivity, and how these parameters vary diurnally, seasonally, and yearly. The measurement sites in this study are spread through the borders of the Houston Ship Channel, with Clinton Drive in the west, Deer Park in the south, and Channelview to the north. Individual reactive species are quantified through time and by source region to help identify key ingredients when the meteorological conditions are prime for ozone production. Results may suggest a remedy for poor ozone air quality days that still persist in the Houston area.