TABLE 1
Annual Exceedances and Variable Averages for Maximum Daily 8-Hour Average (MDA8) Ozone Levels
# of MDA8 Ozone Values >0.070 ppm
Noon Solar Radiation (Langley/min)
MDA8 Ozone (ppm)
Daily Average NO x (ppb)
Maximum Temperature (°F)
Noon Relative Humidity (%)
Noon Wind Speed (mi/hr)
Year
2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023
45 46 35 33 54 44 24 16 22
0.046 0.046 0.045 0.043 0.047 0.048 0.043 0.043 0.043 0.042 0.047 0.045 0.045 0.043 0.042 0.041 0.042 0.050 0.041 0.040 0.043 0.045 0.044
11.0
0.872 0.918 0.892 0.832 0.896 0.938 0.844 0.932 0.889 0.900 0.954 0.918 0.876 0.878 0.843 0.951 0.928 0.891 0.862 0.888 0.873 0.959 0.932
73.7 75.4 74.8 73.4 76.1 77.8 74.2 75.4 74.3 74.5 77.3 77.5 73.8 73.8 74.6 75.4 76.1 74.6 74.3 75.1 74.3 76.8 77.8
58.4 57.9 55.8 55.3 46.5 41.6 54.1 45.3 49.6 49.6 47.3 48.7 51.7 51.0 54.7 51.5 50.7 50.5 51.7 52.1 51.1 46.0 52.9
9.5 9.4 9.8 9.3 9.2 9.8 8.9
8.3
10.7 10.2 13.4 11.4 10.9
9.7 7.8 8.4 8.1 7.3 8.9 8.1 7.2 5.8 5.7 7.4 7.2 6.2 7.4 8.3 5.9
10.0
9.5 9.2
7
37 28 27 10 20
11.5 10.8 10.7 11.1
9.9
9 9 8 5 5
10.2 10.7 10.2 10.0
9.8
16 15 12
10.0 10.4 10.1
Note. NO x = nitrogen oxides.
tive of this study was to identify and evalu- ate associations between MDA8 ozone levels and meteorological and emissions variables at a downwind monitoring station with a tem- poral record exceeding 20 years, including recent anomalous years, in northern Dallas- Fort Worth. Background Emissions of nitrogen oxides (NO x ), vola- tile organic compounds (VOCs), and carbon monoxide (CO) from mobile and station- ary sources react with sunlight to produce ground-level ozone. Several sources emit these precursor gases; sources include motor vehicles, electrical utilities, industrial facili- ties, gasoline vapors, and chemical solvents
(U.S. EPA, 2024a). Suburban and rural areas often experience potentially harmful ozone conditions, as winds carry precursor emis- sions and ozone away from sources in the urban core (Simon et al., 2015). Breathing in high ozone concentrations can impair lung development, damage lung tissue, and harm respiratory system func- tion—especially in vulnerable groups such as children, older adults, and individuals who are active outdoors (Fanucchi et al., 2006; Murphy et al., 2013). Furthermore, exposure to high ozone concentrations exacerbates other lung diseases (U.S. EPA, 2024a). In addition to detrimental eects on rub- ber, paint, and textiles, ozone can damage sensitive vegetation and ecosystems, espe-
cially during the growing season. During plant respiration, ozone enters stomata and oxidizes plant tissue, causing damage, slow- ing growth, and making plants more vulner- able to disease, insect damage, and severe weather (National Park Service, 2020; U.S. EPA, 2024a). Cities with high solar radiation (frequent clear skies), stagnant air (low to light winds), low relative humidity, and heavy emissions of precursor gases are especially prone to haz- ardous ozone concentrations, which tend to peak in mid to late afternoon or early evening (Digar et al., 2013; Sillman & Samson, 1995). Drier conditions favor ozone buildup (Cama- lier et al., 2007), when the lack of moisture causes trees to close stomata to avoid desicca-
9
December 2024 • 9>;8+6 90 8?3;987/8=+6 /+6=2
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