Weekday/Weekend Differences in Ambient Air Pollutant Concentrations in Atlanta and the Southeastern United States

Abstract

The authors quantified changes between mean weekday and weekend ambient concentrations of ozone (O 3 ) precursors (volatile organic compounds [VOC], carbon monoxide [CO], nitric oxide, and oxides of nitrogen [NO x ]) in Atlanta and surrounding areas to observe how weekend precursor emission levels influenced ambient O 3 levels. The authors analyzed CO, nitric oxide (NO), and NO x measurements from 1998 to 2002 and speciated VOC from 1996 to 2003. They observed a strong weekend effect in the Atlanta region, with median daytime (6:00 a.m. to 3:00 p.m. Eastern Standard Time) decreases of 62%, 57%, and 31%, respectively, in the ambient levels of NO, NO x , and CO from Wednesdays to Sundays, during the ozone season (March to October). They also observed significant decreases in ambient VOC levels between Wednesdays and Sundays, with decreases of 28% for the sum of aromatic compounds and 19% for the sum of Photochemical Assessment Monitoring Stations target compounds. Despite large reductions in O 3 precursor levels on weekends, day-of-week differences in O 3 mixing ratios in and near Atlanta were much smaller. Averaging overall O 3 -season days, the 1-hr and 8-hr mean peak daily O 3 maxima on Sundays were 4.5% and 2.3% lower, respectively, than their mean levels on Wednesdays (median of 14 site differences), with no sites showing statistically significant Wednesday-to-Sunday differences. When restricted to high-O 3 days (highest 3 peak O 3 days per day of week per site per year), the 1-hr and 8-hr Sunday O 3 mixing ratios were 11% and 10% lower, respectively, than their mean peak levels on Wednesdays (median of 14 site differences), with 6 of 14 sites showing statistically significant Wednesday-to-Sunday differences. The analyses of weekday/weekend differences in O 3 precursor concentrations show that different emission reductions than normally take place each weekend will be required to achieve major reductions in ambient ozone levels in the Atlanta area.

Effects of improved spatial and temporal modeling of on-road vehicle emissions

“…As a result, higher weekend ozone values are typically seen in VOC-limited areas, whereas NO x -limited areas tend to have lower ozone concentrations on weekends. However, weekend ozone increases or decreases were observed and modeled in some areas, and in other areas no WD/ WE effect was seen (Blanchard and Tanenbaum, 2006;Blanchard et al, 2008;Graedel et al, 1977;Heuss et al, 2003;Koo et al, 2011;Torres-Jardon and Keener, 2006).…”

Summertime weekly cycles of observed and modeled NO<sub>x</sub> and O<sub>3</sub> concentrations as a function of satellite-derived ozone production sensitivity and land use types over the Continental United States

“…differs from that used in previous studies to characterize the weekly cycles of O 3 , including the weekend effect in several urban regions (e.g., Cleveland et al, 1974;Elkus and Wilson, 1977;Vukovich, 2000;Marr and Harley, 2002;Fujita et al, 2003;Lebron, 2004;Qin et al, 2004;Blanchard and Tanenbaum, 2006;Shutters and Balling Jr., 2006;Blanchard et al, 2008;Yarwood et al, 2008). This study categories all of the model grid cells and EPA AQS measurement stations using a dominant AVHRR land use type.…”

“…Therefore, an investigation of the daily or weekly variations of surface O 3 concentrations could illuminate the controlling effects of the key precursors of O 3 concentrations. Previous studies have focused on daily or weekly O 3 variations over several metropolitan areas, including New Jersey, Southern California, Los Angeles, Atlanta, Chicago, Denver, New York City, Dallas, Houston, Phoenix, Washington, DC, Baltimore, and their neighboring regions (e.g., Lebron, 1967;Cleveland et al, 1974;Elkus and Wilson, 1977;Vukovich, 2000;Marr and Harley, 2002;Fujita et al, 2003;Qin et al, 2004;Blanchard and Tanenbaum, 2006;Shutters and Balling Jr., 2006;Blanchard et al, 2008;Yarwood et al, 2008). These studies have highlighted the weekend effect on urban regions, where higher ground-level O 3 concentrations occur during the weekends rather than weekdays.…”

“…Many previous studies (e.g., Lebron, 1967;Cleveland et al, 1974;Elkus and Wilson, 1977;Vukovich, 2000;Marr and Harley, 2002;Fujita et al, 2003;Qin et al, 2004;Blanchard and Tanenbaum, 2006;Shutters and Balling Jr., 2006;Blanchard et al, 2008;Yarwood et al, 2008) showed the weekly pattern of surface NO x and/or O 3 over the AVHRRderived US Geological Survey Land Use Land Cover (USGS LULC) regions (referred to as "AVHRR regions", which consist of urban, forest, and other regions) (Loveland et al, 2000) or GOME-2-derived chemical regimes (referred to as "GOME-2 chemical regimes", which are NO x -saturated, NO x -sensitive, and mixed regimes). Several other studies (e.g., Martin et al, 2004;Duncan et al, 2010) showed how remote sensing products can be used to determine the chemical environment.…”

Variation in Parameters of Ambient Air Quality in National Capital Territory (NCT) of Delhi (India)

“…On the other hand, changing patterns of vehicular traffic and industrial activities also act as a factor for variation in pollution levels. Authors such as Blanchard et al [1], Murphy (2008) et al [2], Fujita et al [3], Gour et al [4], Murphy (2007) et al [5] and Kakoli et al [6] note that weekly cycle of activities of population explains divergent temporal variation in pollution levels from weekdays (Monday to Friday) to weekend (Saturday and Sunday). The paper attempts to carry out an assessment of 24 h daily average concentration of six major pollutants for a period of five years (from 2006 to 2010).…”