Charlotte Ozone

Charlotte Air Quality - Understanding Summertime Ground-Level Ozone Production

There is increasing evidence that high-growth metropolitan areas present formidable challenges for implementing effective ozone attainment strategies. Charlotte is experiencing large population growth, greater increases in vehicle miles traveled, and growing electrical power demands. This region has the highest summertime ozone readings in the Carolinas. A recent research project conducted by chemistry major Jenny Perry focused on correlating regional tropospheric ozone levels with growth in the Charlotte region and with mobile primary pollutant sources (automobiles, buses, and trucks). A comparison of weekday with weekend levels of traffic, ozone precursors, and ozone was made to show how the Charlotte region responds to short-term fluctuations in emission sources. An evaluation of long-term trends was made to provide evidence whether growth-related declines in air quality are being effectively offset by ozone attainment measures.

During the Charlotte ozone project, Jenny worked extensively with both the state of North and South Carolina environmental divisions and with the Departments of Transportation in the Carolinas. She presented her results to the Mecklenburg County Department of Environmental Protection, to the North Carolina Division of Air Quality, and at the national meeting of the Air and Waste Management Association. Upon graduation from Winthrop in 1999, Jenny attended graduate school in chemistry at Duke University and completed her Ph.D. in Biophysical Chemistry in 2003. She was then awarded a prestigious postdoctoral research fellowship at the National Institute for Environmental Health Science (NIEHS) in Research Triangle Park. Dr. Jennifer (Perry) Cecile became a chemistry faculty member at Appalachian State University in 2007 and directs an extensive undergraduate research program. In 2013, Dr. Cecile was named the Honors College Mentor of the Year.

The objectives of Jenny's "Charlotte Ozone Study" study were: 1) to compile Charlotte traffic, CO, NOy, power plant NOx, and ozone data; 2) to examine weekday / weekend variation for each; 3) to evaluate long-term trends; and 4) to examine correlations among traffic patterns, CO, NOy, power plant NOx, and ozone levels. Hourly traffic volumes from 1990-1998 for four tachograph locations were used along with power plant emission data provided by Duke Energy and ambient monitoring data available from EPA and State monitoring systems.

Charlotte Ozone Study Findings

NOy levels (7:00-8:00 AM) were 16% (Saturday) and 49% (Sunday) below the seven day averages. 7:00-8:00 AM CO levels were 8% (Saturday) and 29% (Sunday) below the seven day averages. These pollution patterns emulated traffic pattern variations observed on weekends

In spite of these lower weekend pollutant emissions, Charlotte ozone readings showed little variation in weekday/weekend maximum daily readings. Data from all three ozone monitoring sites during May through September from 1990-1998 had average Sunday and Monday levels of 98% of the 7 day average while Saturday had the highest average ozone level of 102% of the 7 day average.

NOy and CO diurnal patterns showed the greatest weekday / weekend variation during AM rush hours

Traffic volumes increased 53-73% over a seven-year period. Friday was the most traveled day, while Saturday and Sunday morning rush hour traffic counts were 55% and 67% below the seven-day average. Saturday and Sunday traffic totals for all sites were 18% and 31% less than the seven-day average.

Publications

"Weekday/Weekend Variability and Long-Term Trends in Traffic, CO, NOy, and Ozone for the Charlotte Metropolitan Area during the 1990's," **J.L. Perry and P.M. Owens, Proceedings of the Air and Waste Management Association's 94th Annual Conference and Exhibition, 3283-3302, Orlando, 2001.

Presentations

"Charlotte-Rock Hill-Gastonia MSA Summertime Ozone Formation," P.M. Owens, presented at the Winthrop University Environmental Symposium, March 31, 2004.

"Effects of AM Ambient Volatile Organic Compound and Nitrogen Oxide Levels on Same-day Maximum 8-hour Ozone Concentrations in the Charlotte Metropolitan Region for the 1995-2000 Summer Ozone Seasons," **L.M. Lang and P.M. Owens, presentation at the 223rd National meeting of the American Chemical Society, April 8, 2002, Orlando.

"Ozone, Precursors, and Trends for the Charlotte Metropolitan Area," P.M. Owens, **J.L. Perry,** L.M. Lang, **S. Hudson, **G. Ridgeway, S. Few, and P.Lowry, presentation at 2nd annual NC Division of Air Quality Colloquium, May 17, 2002

"An Analysis of Summertime Hydrocarbon Trends, Fingerprints, AM/PM Differences, and Urban/Suburban/Rural Patterns in the Charlotte Region" **Steve Hudson and Pat Owens, presented at the South Carolina Academy of Science Meeting, Coastal Carolina, April 5th, 2001.

"Hydrocarbons in Charlotte Metropolitan Area 1996-1999," **Stephen Hudson and Pat Owens, presented at the NC DAQ Ambient Air Data Analysis Colloquium, May 22, 2001.

"Charlotte Ozone Trends and Precursors,", Pat Owens and **Jenny Perry, presented at the NC DAQ Ambient Air Data Analysis Colloquium, May 22, 2001.

Evaluation of the Variability of GC/FID Analyses of PAMS Standards: April 1999-January 2000, Owens, P.M., Technical Report for the North Carolina Division of Air Quality, April 16, 2001.

"Ramifications of Charlotte Regional Growth and Weekday Activities on Primary and Secondary Emissions," **J.L. Perry and P.M. Owens presented to the North Carolina Division of Air Quality, August, 1999.