Abstract
Secondary pollutant ozone (O3) formation in a particular area is often influenced by various factors. Source of emissions is one of the factors. In south east Texas, Houston-Galveston-Brazoria (HGB) is a marginal non-attainment area for ozone (O3). A summer episode of May 28 to July 2, 2006 is simulated using Comprehensive Air Quality Model with extensions (CAMx). During this period O3 concentration in HGB often exceeds the National Ambient Air Quality Standards (NAAQS) 0.075 ppm of average 8 hour O3 concentration. HGB area has numerous point sources. Various studies found that some specific volatile organic compounds are very reactive in atmosphere. The objective of this study is to analyze the influence of volatile organic compounds present in point source emissions on the air quality of HGB area. For this purpose ozone sensitivity for HGB area is analyzed by the ratio of hydrogen peroxides (H2O2) to nitric acid (HNO3). HGB area is found NOx limited but reactive VOCs are found to be influential too. From (1-4 June, 2006) maximum O3 concentration was found on weekend, June 3. VOCs such as Acetaldehyde (ALD2), Formaldehyde (FORM) and Alkane (ETHA) showed good correlation with O3 concentrations on that day. In addition, Peroxyacetyl nitrate (PAN) formation was found correlated to higher ozone production. Criteria pollutant Sulfur dioxide (SO2) was found to influence the ALD2 and ETHA concentrations, and thus indirectly influenced O3 production.
Highlights
Air pollution is a great challenge for Houston Galveston Brazoria (HGB) area
This paper evaluates the impact of point source emissions on O3 concentrations using EPS3 and Comprehensive Air Quality Model with extensions (CAMx) simulation results
Point source emissions file used for case HGB includes the emissions from the point sources that were present in eight counties of HGB area in 2006
Summary
Air pollution is a great challenge for Houston Galveston Brazoria (HGB) area. Rapid urbanization and industrialization with meteorological variability has taken alarming dimensions for air quality of this area. This area is classified as marginal nonattainment as per 2008 eight-hour ozone NAAQS of 75 ppb [1] [2]. Point source, area source, mobile source, non-road source and biogenic source are the main sources of emissions in this area These sources release various pollutants, such as Nitrogen Oxides (NOx), Volatile Organic Compounds (VOCs), Carbon Monoxide (CO), Sulfur Dioxide (SO2) etc. Among these pollutants NOx and VOCs are the major Ozone(O3) precursors [3]
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