Houston, Texas - Urban air quality studies

Urban zones represent areas in which significant amounts of gaseous pollutants and particulate matter are released into the atmosphere. The Houston-Galveston Brazoria Area (HGB), located close to the Gulf of Mexico, is the fourth largest metropolitan area in the United States. 
The University of Houston (UH) set up an air quality measurement facility at the University main campus on the roof of the 18-story tall North Moody Tower residence hall. The general information about this site is given in Table 1. This facility includes a 35 ft high sampling tower and is equipped with air chemistry measurements including O3, CO, NO, NO2, NO, PAN, PPN, MPAN, VOCs, and meteorological instrumentation. It also includes measurements of photolysis frequencies for O3, NO, HONO and HCHO and 16 other important photolysis reactions.
Aero-Laser equipment is used for the TexAQS II Radical Measurement Project (TRAMP) in 2006 and several other research programs.

Moody Progress Report

Further informations

Publications

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Article

Title: Formaldehyde and its relation to CO, PAN, and SO2 in the Houston-Galveston airshed
Authors: B. Rappenglück, P.K. Dasgupta, M. Leuchner, Q. Li and W. Luke
Journal: Atmos. Chem. Phys.
Year: 2010
Volume: 10
Pages: 2413
DOI: 10.5194/acp-10-2413-2010
Web URL: http://www.atmos-chem-phys.net/10/2413/2010/
Abstract: The Houston-Galveston Airshed (HGA) is one of the major metropolitan areas in the US that is classified as a nonattainment area of federal ozone standards. Formaldehyde (HCHO) is a key species in understanding ozone related air pollution; some of the highest HCHO concentrations in North America have been reported for the HGA. We report on HCHO measurements in the HGA from summer 2006. Among several sites, maximum HCHO mixing ratios were observed in the Houston Ship Channel (HSC), a region with a very high density of industrial/petrochemical operations. HCHO levels at the Moody Tower (MT) site close to downtown were dependent on the wind direction: southerly maritime winds brought in background levels (0.5-1 ppbv) while trajectories originating in the HSC resulted in high HCHO (up to 31.5 ppbv). Based on the best multiparametric linear regression model fit, the HCHO levels at the MT site can be accounted for as follows: 38.5±12.3% from primary vehicular emissions (using CO as an index of vehicular emission), 24.1±17.7% formed photochemically (using peroxyacetic nitric anhydride (PAN) as an index of photochemical activity) and 8.9±11.2% from industrial emissions (using SO2 as an index of industrial emissions). The balance 28.5±12.7% constituted the residual which cannot be easily ascribed to the above categories and/or which is transported into the HGA. The CO related HCHO fraction is dominant during the morning rush hour (06:00-09:00 h, all times are given in CDT); on a carbon basis, HCHO emissions are up to 0.7% of the CO emissions. The SO2 related HCHO fraction is significant between 09:00-12:00 h. After 12:00 h HCHO is largely formed through secondary processes. The HCHO/PAN ratios are dependent on the SO2 levels. The SO2 related HCHO fraction at the downtown site originates in the ship channel. Aside from traffic-related primary HCHO emissions, HCHO of industrial origin serves as an appreciable source for OH in the morning.

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