Region 6 “State of the Ozone” Report for 2014

June 11, 2015

Mark Sather

EPA Region 6 Air Quality Analysis Section
Acknowledgements

 Many thanks to Jason Smith and Diana Greiner 

(RCRA) for the construction of the GIS maps in 

this presentation.

 Additional thanks to Alan Shar, Carrie Paige 

and Kathleen Aisling for their valuable input on 

the Midlothian NOxtrends graphic.
Purple: + 14 areas

Blue: + 24 more areas

Gray: + 8 more areas


In 2014 the DFW area met the 1997 8-hour ozone standard, and the Houston area also went

back under the 1997 8-hour ozone standard. Tulsa, OKC, Little Rock, and

Crittenden Co., AR all went under the 2008 8-hour ozone standard in 2014. San Antonio

remained over the 2008 8-hour ozone standard in 2014.

97-9998-0099-0100-0201-0302-0403-0504-0605-0706-0807-0908-1009-1110-1211-1312-14

Years

60

70

80

90

100

110

120

ppb

8-hour Ozone Trends

Houston

DFW

El Paso

Baton Rouge

OKC

Tulsa

Albuquerque

Little Rock

Beaumont

Crittenden Co., AR

San Antonio

Ozark NF

Big Bend NP

1997 standard (84 ppb)

2008 standard (75 ppb)

Select Region 6 Cities; 3-year running design values
99-01 00-02 01-03 02-04 03-05 04-06 05-07 06-08 07-09 08-10 09-11 10-12 11-13 12-14

Years

60

62

64

66

68

70

72

74

76

78

80

82

84

86

ppb

8-hour Ozone Concentration Trends (Design Values)

 Tribal Sites, OK

Cherokee Tahlequah

Cherokee Stilwell

Cherokee Pryor

Quapaw Tribal

Delaware Tribal

NAAQS

Cherokee Newkirk

Cherokee Roland

2008 8-hour ozone National Ambient Air Quality Standard (NAAQS) = 75 ppb

Design Values = 3-year average of annual 4th highest 8-hour ozone daily maxima
Houston continued to meet the old 1-hr 124 ppb standard with a 

design value of 111 ppb for the 2012 – 2014 time period.

97-99 98-00 99-01 00-02 01-03 02-04 03-05 04-06 05-07 06-08 07-09 08-10 09-11 10-12 11-13 12-14

Years

90

100

110

120

130

140

150

160

170

180

190

200

210

ppb

1-hour Ozone Trends

Select Region 6 Cities; 3-year running design values

Houston

DFW

El Paso

Baton Rouge

Beaumont

old 1-hour standard (124 ppb)
Baton Rouge Long-term VOC and NOx Concentration Trends

June-August weekday; 5-8 AM LST for NOx; 3-9 AM LST for 3-hour integrated 

canisters

For 2014, TNMOC, propane, n-butane and 

propylene concentrations declined, while ethane and 

ethylene increased in concentration. NOx

concentrations in 2014 were similar to 2013, 

remaining lower.

8687888990919293949596979899000102030405060708091011121314

Year

0

10

20

30

40

50

ppb

Baton Rouge Mean Morning NOx Concentrations

Capitol

Port Allen

96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14

Year

0

10

20

30

40

ppbC

0

50

100

150

200

250

300

350

400

tnmoc(ppbC)

tnmoc

ethylene

propylene

n-butane

ethane

propane

Baton Rouge Capitol Mean Morning VOC Concentrations
Beaumont Long-term VOC and NOx Concentration Trends

June-August weekday; 5-8 AM LST

Long-term NOx concentrations have 

significantly declined. VOC concentrations 

have generally declined from 2010-2014 at 

the Downtown site, and from 2011-2014 at 

the Nederland site.

07 08 09 10 11 12 13 14

Year

0

10

20

30

40

50

ppbC

0

100

200

tnmoc(ppbC)

tnmoc

ethylene

propylene

n-butane

ethane

propane

Beaumont Downtown Mean Morning VOC Concentrations

07 08 09 10 11 12 13 14

Year

0

10

20

30

40

50

60

70

80

90

100

ppbC

0

100

200

300

400

500

600

tnmoc(ppbC)

tnmoc

ethylene

propylene

n-butane

ethane

propane

Beaumont Nederland Mean Morning VOC Concentrations

8687888990919293949596979899000102030405060708091011121314

Year

0

10

20

30

ppb

Beaumont Mean Morning NOx Concentrations

Downtown

Nederland

Hamshire

Orange

Sabine Pass NOy
El Paso Long-term VOC and NOx Concentration Trends

June-August weekday; 5-8 AM LST

Long-term VOC and NOx concentrations 

have significantly declined, although 

VOC concentrations have generally 

gradually increased since 2010, except 

for ethylene which has continued to 

decrease.

8687888990919293949596979899000102030405060708091011121314

Year

0

10

20

30

40

50

60

ppb

UTEP

El Paso Mean Morning NOx Concentrations

96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14

Year

0

10

20

30

40

ppbC

0

50

100

150

200

250

300

350

400

tnmoc(ppbC)

tnmoc

ethylene

propylene

n-butane

ethane

propane

El Paso Chamizal Mean Morning VOC Concentrations
Houston Long-term VOC and NOx Concentration Trends

June-August weekday; 5-8 AM LST

VOC concentrations have been 

increasing at the Deer Park and Clinton 

Drive sites since 2011, but NOx 

concentrations at the long-term sites 

remained lower in 2014, except for an 

uptick at the Clinton Drive site.

97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14

Year

0

10

20

30

40

50

ppbC

0

100

200

300

400

tnmoc(ppbC)

tnmoc

ethylene

propylene

n-butane

ethane

propane

Houston Deer Park Mean Morning VOC Concentrations

97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14

Year

0

10

20

30

40

ppbC

0

100

200

300

tnmoc(ppbC)

tnmoc

ethylene

propylene

n-butane

ethane

propane

Houston Clinton Drive Mean Morning VOC Concentrations

8687888990919293949596979899000102030405060708091011121314

Year

0

10

20

30

40

50

60

70

80

90

100

ppb

Houston Mean Morning NOx Concentrations

Clinton Drive

Aldine

Lang

Mae Drive
DFW Long-term VOC and NOx Concentration Trends

June-August weekday; 5-8 AM LST

VOC concentrations (alkanes only) have increased at the 

Dallas Hinton site since 2011. At the Fort Worth 

Meacham site, TNMOC and alkane concentrations 

declined in 2014 after generally increasing since 2009. 

NOx concentrations continued to decrease in 2014 at all 

three long-term area monitoring sites.

96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14

Year

0

10

20

ppbC

0

50

100

150

tnmoc(ppbC)

tnmoc

ethylene

propylene

n-butane

ethane

propane

Dallas Hinton Mean Morning VOC Concentrations

03 04 05 06 07 08 09 10 11 12 13 14

Year

0

10

20

30

40

ppbC

0

50

100

150

tnmoc(ppbC)

tnmoc

ethylene

propylene

n-butane

ethane

propane

Fort Worth Meacham Mean Morning VOC Concentrations

8687888990919293949596979899000102030405060708091011121314

Year

0

10

20

30

40

50

60

70

ppb

DFW Mean Morning NOx Concentrations

Hinton

Meacham

Nuestra Drive
03 04 05 06 07 08 09 10 11 12 13 14

Year

0

5

10

15

20

25

p

p

b

Midlothian NOx Concentration Trends

5-8 AM LST weekday June-August means

Four older kilns at TXI idled late 2008

(permanently shut down in 2010);

One kiln at Holcim idled in 2009

Two older kilns at Ash Grove shut down;

Holcim applying for new NOx controls permit

June 15, 2004: effective date of DFW

nonattainment designation for 1997

8-hour ozone standard;

Holcim SNCR 12/05




H-L H-CL H-CH H-H H-W H-MPH-DP H-CV H-D H-TC H-LJ B-N B-D BR-CBR-PLBR-DBR-PRD-H D-DE D-DI D-ME D-EFD-UTAD-JBD-EML D-K D-R D-FM D-E D-G D-BL D-M SA-F EP-C

Site

0

60

120

180

240

300

360

420

480

540

600

660

Su

mMIRxppbC

City Comparison of mean VOC Reactivity (28-30 species examined per city)

Houston, Beaumont, Baton Rouge, Dallas-Fort Worth, San Antonio, El Paso

Summer (June-August) weekday 5-8 AM LST (Baton Rouge sites summer weekday 3-9 AM LST 3-hour canisters)

2014 data

Houston – purple

Beaumont – yellow

Baton Rouge – dark blue

DFW – green

San Antonio – light blue

El Paso – brown

Red outline = oil/gas compounds dominate
City Comparison of Mean VOC Reactivity

Top 3 Species

 Houston: All HRVOC, dominated by ethylene and propylene, 

and no alkanes in top 3.

 Beaumont: Alkanes at Nederland site, combination of HRVOCs 

and isopentane at Downtown site.

 Baton Rouge: ethylene, propylene and isoprene.

 DFW: reactive VOCs at city sites, but at lower concentrations 

than Houston; alkanes at Barnett Shale sites, dominated by 

ethane, propane and n-butane.

 San Antonio: n-butane, propane, isopentane.

 El Paso: ethylene, propylene and toluene, but at lower 

concentrations than Houston.
Long-term Temperature Trends

June-August; 5 AM – 7 PM LST

DFW and Houston high temperatures were significantly below

the long-term average in 2014, while Baton Rouge recorded a

third consecutive year below the long-term average. El Paso recorded

near long-term average amounts of high degree (i.e. >= 90 deg) days in 2013 and 2014.

76 78 80 82 84 86 88 90 92 94 96 98 00 02 04 06 08 10 12 14

Year

0

10

20

30

40

50

60

70

%oftotal

80

85

90

95

MeanTemp.(deg.F)

% Hourly Temp. >= 90 deg. F

Long-term avg. T >= 90 deg. F

Mean Temp. (deg. F)

Fort Worth Meacham Ambient Temperature

82 84 86 88 90 92 94 96 98 00 02 04 06 08 10 12 14

Year

0

10

20

30

40

50

60

%oftotal

80

85

90

95

MeanTemp.(deg.F)

% Hourly Temp. >= 90 deg. F

Long-term avg. T >= 90 deg. F

Mean Temp. (deg. F)

Houston Aldine Ambient Temperature

93949596979899000102030405060708091011121314

Year

0

10

20

30

40

50

%oftotal

80

82

84

86

88

90

MeanTemp.(deg.F)

% Hourly Temp. >= 90 deg. F

Long-term avg. T >= 90 deg. F

Mean Temp. (deg. F)

Baton Rouge Capitol Ambient Temperature

82 84 86 88 90 92 94 96 98 00 02 04 06 08 10 12 14

Year

0

10

20

30

40

50

60

70

%oftotal

80

85

90

95

MeanTemp.(deg.F)

% Hourly Temp. >= 90 deg. F

Long-term avg. T >= 90 deg. F

Mean Temp. (deg. F)

El Paso UTEP Ambient Temperature
Long-term Wind Speed Trends

June-August; 5 AM – 7 PM LST

There was less stagnation in 2014 compared to 2013

in DFW. Mean wind speeds have generally

been rising in Houston since 2006. El Paso mean wind

speeds have generally been falling since 2011.

Baton Rouge mean wind speeds have generally stayed level since 2006.

76 78 80 82 84 86 88 90 92 94 96 98 00 02 04 06 08 10 12 14

Year

0

10

20

30

40

50

60

70

80

90

100

%

oftotal

0-4 mph

5-9 mph

>= 10 mph

mean rws (mph)

0

1

2

3

4

5

6

7

8

9

meanrws(mph)

Fort Worth Meacham Hourly Resultant Wind Speed Profile

82 84 86 88 90 92 94 96 98 00 02 04 06 08 10 12 14

Year

0

10

20

30

40

50

60

70

80

90

100

%

oftotal

0-4 mph

5-9 mph

>= 10 mph

mean rws (mph)

0

1

2

3

4

5

6

meanrws(mph)

Houston Aldine Hourly Resultant Wind Speed Profile

93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14

Year

0

10

20

30

40

50

60

70

80

90

100

%

oftotal

0-4 mph

5-9 mph

>= 10 mph

mean rws (mph)

0

1

2

3

4

5

6

meanrws(mph)

Baton Rouge Capitol Hourly Resultant Wind Speed Profile

828384858687888990919293949596979899000102030405060708091011121314

Year

0

10

20

30

40

50

60

70

80

90

100

%oftotal

0-4 mph

5-9 mph

>= 10 mph

mean rws (mph)

0

1

2

3

4

5

6

7

8

meanrws(mph)

El Paso Hourly Resultant Wind Speed Profile
State of the Ozone Report for Region 6, 2014 Highlights

 At the end of 2014 there were 3 areas in Region 6 not attaining the 2008 75 ppb 8-hour 

ozone standard, down from 13 areas in 2013.

 Houston continued attaining the old 1-hour ozone standard (124 ppb) with a 2012-2014 

design value of 111 ppb.

 NOx precursor concentrations either continued to decrease, or remained at lower levels, 

in all of the cities, but VOC concentrations continued to increase in Houston. Total VOC, 

including alkane concentrations from signature oil/gas VOC compounds, decreased in 

2014 at the Fort Worth Meacham site after increasing since 2009. NOx concentrations at 

the Midlothian site in the SE DFW area have significantly declined over the long-term.

 Houston has the highest overall VOC reactivity, followed by Beaumont, Baton Rouge, 

DFW, San Antonio and El Paso. In DFW, the second highest VOC reactivity site is Decatur, 

located in the Barnett Shale oil/gas production area, due to an abundance of alkane 

concentrations. The Floresville VOC site in the Eagle Ford Shale south of San Antonio is 

similar to the Decatur VOC site in the Barnett Shale in terms of VOC concentrations and 

reactivity.

 Summer daytime high ambient temperatures (i.e. # hours > 90 deg. F) in 2014 continued 

to stay below average in Baton Rouge and were significantly below average in DFW and 

Houston. Less stagnant winds were recorded in DFW in 2014, while Houston’s wind speed 

distribution in 2014 was similar to 2013.
Region 6 Air Program Topics of Concern 

 San Antonio 8-hour ozone concentrations rising from the 2008-2010 time period to the 

2012-2014 time period, going over the 8-hour ozone standard from 75 ppb (08-10) to 80 

ppb (12-14).

 VOC concentrations, generally the common alkane compounds ethane, propane and 

n-butane, rising in El Paso from 2010-2014, rising in Houston from 2011-2014, and rising at 

the Dallas Hinton site from 2011-2014. These compounds are not highly reactive VOCs 

such as ethylene and propylene, but they can still react with sufficient amounts of NOxto 

form ozone.