Weather Makes a Difference: 8-hour Ozone Trends for 1997-2006 State and Local Information for EPA Region 6 Arkansas Louisiana Oklahoma Texas Composite trend for available sites in these states: EPA Region 06 (selected sites) ^ 80 CL c n 60 O Ž cn CO 50 2 CD > 40 < ro c o CO ffl 20 c/) 30 -=88777^8- Adjusted for Weather Unadjusted for Weather 1998 2000 2002 Year 2004 2006 U.S. Environmental Protection Agency Office of Air and Radiation Office of Air Quality Planning and Standards April 2007 ------- Arkansas Ozone On average, ozone declined 13 percent between 1997 and 2006. These improvements in ozone are in response to both state and regional reductions in NOx and VOC emissions. The level of ozone improvement varies from site to site. Trends for 1997-2006 for rural sites and urban areas with complete ozone and meteorology data are presented below. Ozone season (May 1 - September 30) averages of daily maximum 8-hour ozone were adjusted to remove the influence of year-to-year variability in weather conditions. The dotted line shows the trend in observed values at monitoring sites, while the solid line illustrates the underlying ozone trend after removing the effects of weather. The solid line serves as a more accurate ozone trend for assessing changes in emissions. Typical weather conditions are determined by averaging conditions (e.g., temperature, humidity, etc.) for the time period presented. The information provided is useful for reviewing the weather influence for a particular ozone season. The solid line represents ozone levels anticipated under typical weather conditions. Seasonal Average 8-hour Ozone Trends Little Rock AR .Q CL Q. CD 80 c o N O Ŗ,60 CO 2 CD - 40 CO c o c/) CO CD 20 an o. % " o Adjusted for Weather Unadjusted for Weather 1998 2000 2002 Year 2004 2006 ------- Caddo Valley, AR .Q CL Q. CD 80 c o N O Ŗ,60 O) CO CD - 40 CO c o CO CO CD 20 |C/) Adjusted for Weather Unadjusted for Weather 1998 2000 2002 Year 2004 2006 ------- Louisiana Ozone On average, ozone declined 8 percent between 1997 and 2006. These improvements in ozone are in response to both state and regional reductions in NOx and VOC emissions. The level of ozone improvement varies from site to site. Trends for 1997-2006 for rural sites and urban areas with complete ozone and meteorology data are presented below. Ozone season (May 1 - September 30) averages of daily maximum 8-hour ozone were adjusted to remove the influence of year-to-year variability in weather conditions. The dotted line shows the trend in observed values at monitoring sites, while the solid line illustrates the underlying ozone trend after removing the effects of weather. The solid line serves as a more accurate ozone trend for assessing changes in emissions. Typical weather conditions are determined by averaging conditions (e.g., temperature, humidity, etc.) for the time period presented. The information provided is useful for reviewing the weather influence for a particular ozone season. The solid line represents ozone levels anticipated under typical weather conditions. Seasonal Average 8-hour Ozone Trends New Orleans, LA .Q CL Q. CD 80 c o N O Ŗ,60 CO CO CD - 40 CO c o c/) CO .9 20 c/) O. Adjusted for Weather Unadjusted for Weather 1998 2000 2002 Year 2004 2006 ------- Baton Rouge, LA .Q CL Q. CD 80 c o N O Ŗ,60 O) CO CD - 40 CO c o CO CO CD 20 |C/) Adjusted for Weather Unadjusted for Weather 1998 2000 2002 Year 2004 2006 ------- Oklahoma Ozone On average, ozone did not change between 1997 and 2006. Ozone trends vary from site to site. Trends for 1997-2006 for rural sites and urban areas with complete ozone and meteorology data are presented below. Ozone season (May 1 - September 30) averages of daily maximum 8-hour ozone were adjusted to remove the influence of year-to-year variability in weather conditions. The dotted line shows the trend in observed values at monitoring sites, while the solid line illustrates the underlying ozone trend after removing the effects of weather. The solid line serves as a more accurate ozone trend for assessing changes in emissions. Typical weather conditions are determined by averaging conditions (e.g., temperature, humidity, etc.) for the time period presented. The information provided is useful for reviewing the weather influence for a particular ozone season. The solid line represents ozone levels anticipated under typical weather conditions. Seasonal Average 8-hour Ozone Trends Tulsa, OK .Q CL Q. CD 80 c o N O Ŗ,60 CO 2 CD ^ 40 CO c o c/) CO |S20 ,.0. ...o Adjusted for Weather Unadjusted for Weather 1998 2000 2002 Year 2004 2006 ------- Oklahoma City, OK .Q CL Q. CD 80 c o N O Ŗ,60 O) CO CD - 40 CO c o CO CO CD 20 |C/) - ' _. o " O ' ' Adjusted for Weather Unadjusted for Weather 1998 2000 2002 Year 2004 2006 ------- Texas Ozone On average, ozone did not change between 1997 and 2006. There have been improvements in Dallas and Houston in recent years. These improvements in ozone are in response to both state and regional reductions in NOx and VOC emissions. Ozone trends vary from site to site. Trends for 1997-2006 for rural sites and urban areas with complete ozone and meteorology data are presented below. Ozone season (May 1 - September 30) averages of daily maximum 8-hour ozone were adjusted to remove the influence of year-to-year variability in weather conditions. The dotted line shows the trend in observed values at monitoring sites, while the solid line illustrates the underlying ozone trend after removing the effects of weather. The solid line serves as a more accurate ozone trend for assessing changes in emissions. Typical weather conditions are determined by averaging conditions (e.g., temperature, humidity, etc.) for the time period presented. The information provided is useful for reviewing the weather influence for a particular ozone season. The solid line represents ozone levels anticipated under typical weather conditions. Seasonal Average 8-hour Ozone Trends San Antonio, TX .Q CL CL CD 80 - c o N O CO c o c/) Adjusted for Weather Unadjusted for Weather 1998 2000 2002 2004 2006 Year ------- Austin, TX .Q CL Q. CD 80 c o N O Ŗ,60 O) CO CD - 40 CO c o CO CO CD 20 an " o - " Adjusted for Weather Unadjusted for Weather 1998 2000 2002 Year 2004 2006 Big Bend NP, TX .Q CL Q. CD 80 c o N O Ŗ,60 CO CO CD - 40 CO c o c/) CO CD 20 |C/) Adjusted for Weather Unadjusted for Weather 1998 2000 2002 Year 2004 2006 ------- Dallas, TX .Q CL CL CD 80 " c o N O Ŗ,60 - CO CO .oģģ_ o* # I o ^r I0AV IBUO CO CO cd 20 - 75 Adjusted for Weather Unadjusted for Weather i i i i i 1998 2000 2002 2004 2006 Year El Paso, TX .Q CL Q. CD 80 c o N O Ŗ,60 O) CO CD - 40 CO c o CO CO CD 20 |C/) m8 Adjusted for Weather Unadjusted for Weather 1998 2000 2002 Year 2004 2006 ------- Houston, TX .Q CL Q. CD 80 c o N O Ŗ,60 O) CO CD - 40 CO c o CO CO CD 20 an o. , ttrr. ,^rr-s^r Adjusted for Weather Unadjusted for Weather 1998 2000 2002 Year 2004 2006 ------- |