Precursor Reductions and Ground-Level Ozone in the Continental U.S.
1
2
3
Supplemental Material
4
5
Table S1. Ozone nonattainment areas subject to PAMS. Classification is based on level of observed 1-hr
O3 maxima (DVs) adopted for the NAAQS prior to 1997 (EPA, 2014a).
Area
EPA Classification
Atlanta, GA
Baltimore, MD
Serious
Severe
Baton Rouge, LA
Serious
Boston-Lawrence-Worcester, MA-NH
Serious
a
Chicago-Gary-Lake County (IL), IL-IN-WI
Severe
Dallas-Fort Worth, TX
Serious
El Paso, TX
Serious
Greater Connecticut, CT
Serious
Houston-Galveston-Brazoria, TX
Severe
Los Angeles-South Coast Air Basin, CAb
Extreme
a
Milwaukee-Racine, WI
Severe
New York-New Jersey-Long Island, NY-NJ-CT
Severe
Phoenix, AZ
Serious
Philadelphia-Wilmington-Trenton, PA-NJ-DE-MD
Severe
Portsmouth-Dover-Rochester, NH-ME
Serious
Providence-Pawtucket-Fall River, RI-MA
Serious
Sacramento, CA
Severe
San Diego, CA
Serious
San Joaquin Valley, CA
Serious
Santa Barbara-Santa Maria-Lompac, CA
SE Desert Modified AQMA, CA
Serious
b
Severe
Springfield, MA
Serious
Ventura County, CA
Severe
Washington, DC-MD-VA
Serious
6
a
7
8
b
Chicago and Milwaukee are combined into one PAMS area referred to as Lake Michigan.
Los Angeles-South Coast and SE Desert Modified AQMA are combined into one PAMS area referred to as South
Coast-SEDAB
9
10
1
11
12
13
14
15
16
17
18
19
20
21
22
23
Table S2. Estimates of precursor emission changes vs. ozone design value (DV) changes by state 20002011. Trends are not monotonic and generally show reductions with precursors, especially with regional
NOx emissions. The reductions in DV, running average over three years, are fit to a linear least squares
regression (Midwest Ozone Group, 2013).
%NOx
%NOx/yr
%VOCc
%VOC
/yr
VOC/
NOxe
Avg DV
ppbv
O3/yrb
%O3/yr
Calif.
Oregon
Washington
Arizona
Wyoming
-40
-45
-12
-40
-45
-3.3
-3.8
-1.0
-3.3
-3.8
-44
-74
-30
-28
121d
-3.7
-6.2
-2.5
-2.3
10
0.90
1.0
0.74
0.78
1.4
-0.79a
-0.12
-0.40
-0.71
-0.13
-0.72
-0.2
-0.6
-0.9
-0.2
Avg.
2011
DV
(ppbv)
78
60
61
75
65
Montana
-43
-3.6
-45
-3.8
0.48
0.19
0.4
57
Minnesota
-32
-2.7
-31
-2.6
0.91
-0.31
-0.9
28
Illinois
Missouri
Ohio
Texas
-37
-40
-47
-26
-3.1
-3.3
-3.9
-2.2
-39
-52
-41
84d
-3.3
-4.3
-3.4
7
-1.3
-1.33
-1.72
-1.53a
-1.7
-1.6
-2
-1.7
70
75
76
80
Louisiana
Maryland
New York
Georgia
N. Carolina
-44
-50
-45
-41
-45
-3.7
-4.2
-3.8
-3.4
-3.8
-24
-54
-47
-32
-37
-2.0
-4.5
-3.9
-2.7
-3.1
0.72
1.6
0.77
1.81
(0.73f)
0.59
0.76
-1.1
0.84
1.0
-1.0
-1.95
-1.7
-1.72
-1.9
-1.2
-1.8
-1.5
-1.8
-2.2
78
80
72
70
72
Region
State
West
NW
NW
SW
West N
Central
West N
Central
East N
Central
Central
Central
Central
South
South
NE
NE
SE
SE
a
Max. DV change much higher > 2 ppbvO3/yr
Based on 2001-2011 values extrapolated to 2000-2011; 2000 O3 DV uncertain
c
Sharp increases in 2011 inventory for VOC assumed to be oil-gas production
d
Wyoming VOC large increase 2003-2005 and decline 2010 may show up in DV slight increase in 2005 and slight
decrease in 2010. Texas VOC strong increase in 2010-2011 DV up slightly after 2010.
e
Mass ratio based on 2011 emission data
f
Based on 2010 data
b
2
24
25
Table S3. Some similarities and differences in climate conditions in representative cities for ozone nonattainment areas.
City or urban
region
Atlanta, GA
Birmingham,
AL
Chicago, IL
Detroit, MI
26
27
28
29
30
31
32
33
34
35
36
37
38
39
July
Average
High
T (oF)c
90
91
JulyAfternoon
RH (%)d
Annual
Precip (in.)c
Max.
Precip.
(mo.)c
Sun (%
days)d
July Max.
Mixing Ht.
(m)b
58
57
49.7
54
Jan-Apr; Jul
Mar-Apr
60
58
1600
1600
Potential
for %
extrastatea
65
63
84
82
54
52
39
31
May-Aug
Apr-May;
Aug
Apr-May;
Oct
May-June
Jan-Feb
54
53
1380
1200
56
63
Dallas-Fort
96
42
37.5
1800
10
Worth, TX
Houston, TX
94
55
58
59
1300
10
Los Angeles,
77e
68e
18.7
73
460
8
CA
Los Angeles
94
30
10.3
Jan-Feb.
75
1200
8
East
(Riverside,
CA)f
San Francisco,
67
59
23.6
Dec-Mar
66
430
8
CA
San Joaquin
92
28
15.2-18.5
Nov-Mar
70
2700
8
and
Sacramento,
CA
Southern
85
53
46.2
Mar-May;
58
800
79
New York, Jul
Southern
Conn.
Baltimore,
87
53
40.8
Jul-Sept
64
800
69
MdWashington,
DC
a
Estimate of interstate transport impact as a fraction of total emissions, based on calculations of Tong and
Mauzerall (2008).
b
From Holzworth (1964)
c
From US Climate Data. www.usclimate data.com (accessed March 2015).
d
From Current results/weather and science facts. www.currentresults.com/wWeather/us/humidity-city-july.php
(accessed March 2015).
e
Airport data far-western Los Angeles Basin near ocean (marine influenced).
f
Far eastern Los Angeles Basin. Note change from coastal conditions to east arid conditions.
3
40
41
42
43
44
45
46
Table S4. Linear regression models relating annual-average ambient concentrations of NOy, NMOC, and
peak 8-hour O3 (units: ppbv for O3 and NOy, ppbC for NMOC) to annual, regionala chemical emissions
(units: million metric tons/yr.). Statistically significant (p < 0.05) results are indicated by bold-face p
values (after Hidy et al., 2014). Data were available for 1996 – 2013 for emissions, 1992 – 2013 for rural
O3 and NOy, 1999 – 2013 for Jefferson Street (Atlanta) O3 and NOy, 1999 – 2008 for JST Atlanta NMOC,
2000 – 2013 for Birmingham O3, and 2001 – 2013 for NOy.
Model
N
(yrs)
13
Variance
(r2)
0.928
p value
(slope)
<0.0001
p value
(intercept)
0.585
JSTe NOy = 35.640 (± 4.880)* (NOx emissions) – 5.326 (± 6.256)
15
0.804
<0.0001
0.410
Ruralf NOy = 3.170 (± 0.313)* (NOx emissions) + 0.113 (± 0.432)
18
0.865
<0.0001
0.797
JST NMOC = 3144.9 (± 523.2)*(VOC emissions ) – 37.2 (± 44.8)
11
0.801
0.0002
0.428
BHMd O3 = 5.492 (± 1.868)* (NOx emissions) + 40.552 (± 4.270)
14
0.177
0.1345
<0.0001
BHM O3 = 8.462 (± 7.173)*(VOC emissions ) + 38.148 (± 7.733)
14
0.104
0.2610
0.0003
JSTe O3 = 6.432 (± 2.567)* (NOx emissions) + 42.564 (± 3.290)
15
0.326
0.0263
<0.0001
JST O3 = 9.301 (± 5.777)*(VOC emissions ) + 40.466 (± 6.319)
15
0.166
0.1314
<0.0001
Ruralf O3 = 10.093 (± 1.868)* (NOx emissions) + 36.98 (± 2.582)
18
0.560
<0.0001
<0.0001
18
0.466
0.0018
0.0002
BHMd NOy = 22.709 (± 1.900)* (NOx emissions) + 1.296 (± 2.302)
b
d
e
c
b
f
Rural O3 = 19.667 (± 5.259)*(VOC emissions) + 28.65 (± 5.88)
47
48
49
50
51
52
53
54
55
a
Total annual emissions from GA, AL, MS and NW FL
GA on-road mobile source VOC emissions
c
Mobile-source emissions from GA, AL, MS and NW FL
d
Birmingham, AL (BHM)
e
Atlanta, GA, Jefferson St. Site (JST)
f
Rural SEARCH sites used are located at Centreville, AL, Yorkville, GA, and Oak Grove, MS.
b
56
4
57
58
59
Table S5. NOx emissions by region and year, with CAMx model-predicted reductions needed to achieve
current and alternative levels of O3 NAAQS. Regions are defined in the regulatory impact analysis (RIA)
(EPA, 2015a). Units are tons for all columns.
NOx Emissionsa
NOx Emission Reductions
To
2025
Area
National
California
2011
2018
Base
579,596
460,071
236,000
693,000
1,970,000
3,540,000
5,000
191,000
53,000
110,000
140,000
45,000
640,000
1,750,000
2,900,000
240,000
510,000
720,000
430,000
870,000
828,000
1,258,000
6,895,486
6,226,000
378,000
Northeast
2,030,203
1,403,225
1,188,626
1,074,000
55,000
Midwest
2,989,566
2,064,402
1,779,916
1,771,000
129,000
Central
3,409,666
2,617,452
2,295,595
2,073,000
98,000
Southeast
2,006,385
1,300,975
1,041,393
962,781
702,350
589,956
1,854,784
1,346,516
1,120,999
Northwest
649,212
455,354
356,546
Southwest
1,205,572
891,162
764,453
North
Central
West
60
61
62
63
64
65
66
67
a
68
69
70
b
71
72
73
c
74
75
76
77
78
d
To
436,000
11,398,601 8,088,404
East
To
Achieve Achieve Achieve Achieve
2025
Baselineb From CPPc 75 ppbvd 70 ppbvd 65 ppbvd 60 ppbvd
13,993,540 10,019,951 8,512,357
740,163
To
45,000
408,000
57,000
1,025,000
53,000
110,000
500,000
713,000
46,000
110,000
500,000
2011, 2018, and 2025 Base emissions for continental US excluding offshore outside exclusive economic zone
(obtained from ftp://ftp.epa.gov/EmisInventory/2011v6/ozone_naaqs/reports/). National total is equal to EPA
Base Emissions Modeling TSD (November 2014) Table 5-6 (total US). EPA projections to 2018 and base-2025 are
based on EPA modeling inventories that represent future-year emissions based on population growth, future
emission-source activity levels, and final emission control regulations (including vacated measures but not
including rules that are under consideration or additional emission reductions modeled for O 3 NAAQS attainment).
EPA Base Emissions Modeling TSD (November 2014) Tables 5-1 through 5-3, EPA trends inventory, and 2011 NEI
and 2018 modeling inventory differ slightly from tabled values.
RIA Tables 3-3 and 4-5. Listed 2025-baseline emissions are for controlled sectors only, and are therefore not true
totals. The total 2025-baseline emissions are not explicitly listed in the RIA, and include a proposed rule, section
111(d) (Clean Power Plan).
NOx emission reductions from section 111(d) (Clean Power Plan) ( EPA, 2015g). The data are from CPP RIA Table
4-11 (“all-year NOx”, “Option 1 – State”), as utilized in the ozone RIA. NOx reductions for the “East” and “West”
regions were allocated to subregions in proportion to 2011 NEI state EGU NOx emissions.
RIA Emission reductions beyond CPP for achieving 75 ppbv O 3 NAAQS (combined with CPP, these yield 2025baseline emissions), and for 70 – 60 ppbv alternative NAAQS. Sum of known controls, unknown controls, CA post2025 controls. Tables ES-1 through ES-5, 3A-3 through 3A-6 and 4-2 through 4-11. These reductions are in addition
to section 111(d). Reductions to attain 70 – 60 ppbv alternative NAAQS are also in addition to the reductions to
attain 75 ppbv.
79
5
80
81
82
Table S6. VOC emissions by region and year, with CAMx model-predicted reductions needed to achieve
current and alternative levels of O3 NAAQS. Regions are defined in the RIA (EPA, 2014b). Units are tons
for all columns.
VOC Emissionsa
VOC Emission Reductions
2025
Area
2011
2018
Base
17,521,107
15,706,933
15,138,992
864,441
762,502
726,639
13,144,590
11,684,165
11,238,157
Northeast
1,849,053
1,493,198
1,406,749
Midwest
2,470,029
2,026,290
1,934,725
Central
4,957,200
4,839,201
4,734,681
Southeast
2,723,451
2,272,950
2,148,183
North Central
1,144,857
1,052,526
1,013,819
3,512,076
3,260,266
3,174,196
Northwest
1,389,935
1,282,857
1,245,920
Southwest
2,122,141
1,977,409
1,928,276
National
California
East
West
2025
Baselineb
From CPPc
To
To
To
To
Achieve
Achieve
Achieve
Achieve
75 ppbvd
70 ppbvd
65 ppbvd
60 ppbvd
37,000
36,000
42,000
28,000
73,000
35,000
36,000
7,000
7,000
51,000
18,000
83
84
a
85
b
RIA Tables 3A-3 through 3A-6.
86
c
Clean Power Plan (EPA, 2014c) does not yield VOC emission reductions.
87
88
89
d
2011, 2018, and 2025 Base emissions for continental US excluding offshore outside EEZ (obtained from
ftp://ftp.epa.gov/EmisInventory/2011v6/ozone_naaqs/reports/).
2025 baseline emissions are for achieving 75 ppbv O3 NAAQS. Table 3A-3 reports 51,000 tons; Table 4-3 reports
48,000 tons. VOC reductions for 70 – 60 ppbv are in addition to the VOC reductions included in the 2025 baseline
inventory.
90
91
92
93
94
95
6
96
97
Table S7. Calculated emission influenced background median fraction (%) of hourly observed O3 levels
for spring and summer (from Lefohn et al., 2014)
Location
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
Spring
Summer
Atlanta, GA
51
32
Baltimore, MD
51
36
Chicago, IL
56
43
Dallas, TX
56
47
Detroit, MI
59
45
Houston, TX
60
44
Los Angeles, CA
60
48
New York, NY
59
39
Sacramento, CA
69
55
Washington, DC
49
36
Figure S1. Designated air quality-climate regions of the United States used for meteorologically adjusted
O3 concentrations (see Figure 5) (from EPA, 2013). Northeast (dark blue), Southeast (green-yellow),
Central (red), East North Central (light green), West North Central (blue), South (light blue),
Southwest (gold), West (orange), Northwest (aqua).
7
)v)
4
3
2
1
0
4
3
2
1
Emi ssions (million tons)
5
b.
154
0
)v)
155
156
Emi ssions (million tons)
a.
)v)
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
c.
5
158
4
159
3
160
2
161
1
162
Emi ssions (million tons)
6
157
0
163
164
165
166
167
Figure S2. Trends in summer average (red) and meteorologically-adjusted O3 concentrations (blue)
reported by EPA (2013) with NEI regional NOx (green) and VOC emissions (black) superimposed. The
comparison indicates that the mean O3 concentrations decline with emissions but with less than 1:1
proportionality. A graph is included for each of the regions in Figure S1.
8
)v)
d.
2
169
1.5
170
171
1
172
0.5
173
0
Emi ssions (million tons)
168
1.2
e.
176
1
177
0.8
178
0.6
179
0.4
0.2
180
0
)v)
181
182
Emi ssions (million tons)
175
)v)
174
5
f.
4
184
3
185
186
2
187
1
188
0
189
190
Figure S2 (continued).
191
9
Emi ssions (million tons)
183
)v)
1.2
192
g.
0.8
194
0.6
195
0.4
196
0.2
197
0
Emi ssions (million tons)
1
193
2
h.
1.8
1.6
1.4
201
1.2
1
202
0.8
203
0.6
0.4
204
0.2
0
207
)v)
205
206
1.5
i.
208
1
209
210
0.5
211
212
0
213
214
Emi ssions (million tons)
200
Figure S2 (continued).
215
10
Emi ssions (million tons)
199
)v)
198
216
222
Year
SoCAB O3
Emissions (tons per day)
35
30
20
25
20
20
20
15
20
10
20
05
20
00
20
95
0
75
35
30
200
0
20
25
20
20
20
15
20
10
20
05
20
00
20
95
20
90
19
85
19
19
19
80
0
75
0
400
0.02
20
500
90
0.05
600
0.04
19
1000
800
85
0.1
1400
1000
0.06
19
1500
80
0.15
1600
1200
0.08
19
2000
0.1
O3 (ppmv)
0.2
San Francisco Bay Area Air Basin
19
221
2500
0.12
19
220
0.25
19
219
O3 (ppmv)
218
3000
South Coast Air Basin
Emissions (tons per day)
0.3
217
Year
SoCAB NOx
SoCAB ROG
SFBA O3
SFBA NOx
SFBA ROG
223
SJV O3
SJV NOx
35
30
20
25
20
20
20
15
20
10
20
05
20
20
75
35
0
Year
229
Emissions (tons per day)
50
0
20
30
20
25
20
20
20
15
10
20
20
05
20
00
20
95
90
19
19
85
19
80
19
19
228
0
75
0
100
0.02
00
200
150
20
0.02
200
0.04
95
400
90
0.04
250
0.06
19
600
300
85
0.06
350
0.08
19
800
400
19
0.08
450
0.1
80
1000
500
Sacramento Valley Air Basin
0.12
19
227
0.1
0.14
19
226
O3 (ppmv)
225
1200
O3 (ppmv)
224
1400
San Joaquin Valley Air Basin
0.12
Emissions (tons per day)
0.14
Year
SJV ROG
SV O3
SV NOx
SV ROG
230
231
232
233
Figure S3. Comparison between five-year weighted average of annual 4th-highest daily peak 8-hr O3
concentrations in four California air basins and annual precursor emission trends (data from CARB 2013;
2014). The 5-year O3 averages are centered on the emission year.
234
235
11
236
237
45
40
238
241
30
20
C5 (ppbC)
240
25
35
C234 (ppbC)
239
30
25
20
15
15
10
10
5
5
0
2000
243
245
246
247
248
249
250
BTEX (ppbC)
244
2002
2004
2006
2008
Year
2010
2012
0
2000
2014
16
8
14
7
12
6
Isoprene (ppbC)
242
10
8
6
1
2006
2008
Year
2010
2012
2014
2010
2012
2014
3
2
2004
2006
2008
Year
4
2
2002
2004
5
4
0
2000
2002
0
2000
2002
2004
2006
2008
Year
2010
2012
2014
Central
EastNorthCentral
251
Northeast
252
Southeast
253
254
255
256
South
Southw est
West
Figure S4. Concentrations of groups of speciated NMOC from PAMS sites, averaged across sites within
each region. Species groupings of anthropogenic origin are C2-C4 alkanes (C234), pentanes (C5), and
BTEX aromatics; isoprene is an indicator of natural emissions. Data from EPA archives, 2002-2012.
257
258
12
O3_Max_4 (ppbv)
a. Los Angeles,
NO2 (ppbv)
O3_Max_4 (ppbv) = 44.289 + 1.389 * NO2 (ppbv); R^2 = .578
O3_Max_4 (ppbv) = 87.647 + 1.608 * Toluene (ppbC); R^2 = .758
0
10
20
30
40
50
60
70
Toluene (ppbC)
80
90
100
NO2 (ppbv) or toluene
140
b. Bridgeport,
O3_Max_4 (ppbv)
120
100
80
60
40
NO2 (ppbv)
O3_Max_4 (ppbv) = 55.951 + 1.236 * NO2 (ppbv); R^2 = .676
O3_Max_4 (ppbv) = 79.162 + 5.901 * Toluene (ppbC); R^2 = .43
20
Toluene (ppbC)
0
0
5
10
15
20
25
30
NO2 (ppbv) or toluene
35
40
45
50
140
c. Chicago,
O3_Max_4 (ppbv)
120
100
80
60
40
NO2 (ppbv)
O3_Max_4 (ppbv) = 79.485 + .248 * NO2 (ppbv); R^2 = .026
O3_Max_4 (ppbv) = 84.671 + 1.099 * Toluene (ppbC); R^2 = .221
20
Toluene (ppbC)
0
0
10
20
30
40
NO2 (ppbv) or toluene
50
60
70
140
d. Atlanta, GA
120
O3_Max_4 (ppbv)
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
200
180
160
140
120
100
80
60
40
20
0
100
80
60
40
O3_Max_4 (ppbv) = 38.581 + 1.59 * NO2 (ppbv); R^2 = .626
O3_Max_4 (ppbv) = 86.032 + 2.335 * Toluene (ppbC); R^2 = .292
20
NO2 (ppbv)
Toluene (ppbC)
0
0
10
20
30
40
50
NO2 (ppbv) or toluene
Figure S5. Example univariate regression results for annual 4th-highest daily peak 8-hr O3 vs. either
annual average peak 1-hour NO2 concentrations or annual average toluene concentrations (an indicator
for motor vehicle VOC emissions): a. Los Angeles—known to be NMOC limited; b. Bridgeport-Stamford,
CT -- representative of New York CBSA area, and affected by local and transported O3 and precursors; c.
Chicago--suspected to be NMOC limited and affected by transport around the Great Lakes; d. Atlanta locally NMOC sensitive but regionally NOx sensitive, and affected by regional stagnation (Blanchard et
al., 2010). Other examples of O3 regressions by CBSA tend to show a stronger r2 for NO2 than toluene.
13
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
Figure S6. Example of an O3 isopleth (Haagen-Smit or EKMA) plot applicable to Los Angeles, California,
reproduced from Fujita et al. (2003). Modeled initial concentrations of NOx and NMHC (NMOC) during
the summers of 1999 and 2000 with error bars for observations representing 1 standard deviation from
the mean at (A) Azusa, (L) downtown Los Angeles, (P) Pico, and (U) Upland locations (Fujita et al., 2003).
Squares are for Wednesday and circles are Sunday. The white diamonds are conditions for summer
1987. Modeled O3 concentrations are for maximum achievable concentrations with initial precursor
concentrations. Data for a weekday in 2010 were estimated to be comparable to weekend
concentrations in 2000, i.e. to move approximately parallel to the isopleths between 80 and 120 ppbv O3
relative to the 1999-2000 locations (Fujita et al., 2003; 2006). For this change in precursors, the change
in calculated O3 concentration is small according to this diagram (Fujita et al., 2013).
332
333
14
334
336
337
a. Augusta, GA
120
O3_Max_4 (ppbv)
335
140
100
80
60
40
20
338
NO2 (ppbv)
O3_Max_4 (ppbv) = 68.435 + 1.636 * NO2 (ppbv); R^2 = .319
O3_Max_4 (ppbv) = 81.853 + .024 * Toluene (ppbC); R^2 = .001
Toluene (ppbC)
0
0
339
343
30
60
NO2 (ppbv)
40
Toluene (ppbC)
O3_Max_4 (ppbv) = 53.475 + 1.152 * NO2 (ppbv); R^2 = .691
0
5
10
15
20
25
30
35
NO2 (ppbv) or toluene (ppbC)
345
140
c. Gettysburg, PA
120
O3_Max_4 (ppbv)
348
25
80
0
347
20
100
20
344
346
15
NO2 (ppbv) or toluene (ppbC)
b. Columbia, SC
120
O3_Max_4 (ppbv)
342
10
140
340
341
5
100
80
60
40
20
349
NO2 (ppbv)
O3_Max_4 (ppbv) = 51.945 + 3.757 * NO2 (ppbv); R^2 = .287
O3_Max_4 (ppbv) = 66.96 + 10.866 * Toluene (ppbC); R^2 = .074
Toluene (ppbC)
0
0
350
1
2
3
O3_Max_4 (ppbv)
354
357
358
359
360
8
80
60
40
NO2 (ppbv)
O3_Max_4 (ppbv) = 55.89 + 2.5 * NO2 (ppbv); R^2 = .854
O3_Max_4 (ppbv) = 99 - 3.014 * Toluene (ppbC); R^2 = .67
Toluene (ppbC)
0
0
356
7
100
20
355
6
d. Tyler, TX
120
353
5
140
351
352
4
NO2 (ppbv) or toluene (ppbC)
2
4
6
8
10
12
14
16
NO2 (ppbv) or toluene (ppbC)
Figure S7. Example variations of O3 with mean 1-hr maximum NO2 and mean toluene concentrations in
CBSAs where recent mean NO2 concentrations are less than or close to 10 ppbv. In these relatively low
NO2 regimes, there is no evidence of departure from a linear O3-NO2 relationship. The O3-NO2
relationships are stronger than the O3-toluene relationships. Toluene data for Tyler are limited.
15
361
362
References for Supplement
363
364
California Air Resources Board. 2013. California state emissions trends.
www.arb.ca.gov/app/emsinv/fcemssumcat2013.php (accessed January, 2015).
365
366
California Air Resources Board. 2014. Air quality data. www.arb.ca.gov/aqd/almanac/almanac/htm
(accessed January, 2015).
367
368
EPA. 2013. Trends in Ozone Adjusted for Weather Conditions.
http://www.epa.gov/airtrends/weather.html (accessed 10/6/2013).
369
370
EPA. 2014a. PAMS Network and Sites. http://www.epa.govttnamti1/pamssites.html (accessed Dec. 14,
2014).
371
372
373
EPA. 2014b. Regulatory Impact Analysis for the Proposed Revisions of the National Ambient Air Quality
Standard for Ozone. http.www.epa.gov/ttn/naaqs/standards/ozone/a_o3_ria.html (accessed January,
2015).
374
375
376
377
EPA. 2014c. Regulatory Impact Analysis for the Proposed Carbon Pollution Guidelines for Existing Power
Plants and Emission Standards for Modified and Reconstructed Power Plants. EPA-452/R-14-002. June
2014. http://www2.epa.gov/carbon-pollution-standards/clean-power-plan-proposed-rule-regulatoryimpact-analysis (accessed March 2015).
378
379
380
Fujita, E., Stockwell, W., Campbell, D., Keisslar, R., and D. Lawson. 2003. Evolution of the magnitude and
spatial extent of the weekend ozone effect in California’s South Coast Air Basin, 1981-2000. J. Air &
Waste Manage. Assoc. 53: 802-815.
381
382
383
384
Fujita, E. 2006. Appendix J. In Lurmann, F. Summary of the Ozone Air Quality Forum and Technical
Roundtable. Report STI-906051-3149-FR, Petaluma, CA: Sonoma Technology, Inc.
www.aqmd.gov/docs/default-source/technology-research/TechnologyForums/ozoneforumsummary.pdf?sfvrsan=0 (accessed December 2014).
385
386
387
Fujita, E. M., D. E. Campbell, W. R. Stockwell, and D. R. Lawson. 2013. Past and future ozone trends in
California’s South Coast Air Basin: Reconciliation of ambient measurements with past and projected
inventories. J. Air & Waste Manage. Assoc. 63: 54 – 69, DOI: 10.1080/10962247.2012.735211.
388
389
390
Hidy, G., Blanchard, C., Baumann, K., Edgerton, E., Tananbaum, S., Shaw, S., Knipping, E., Tombach, I.,
Jansen, J. and J. Walters. 2014. Chemical climatology of the southeastern United States, 1999-2013.
Atmos. Chem. Phys. 14: 11893-11914.
391
392
Holzworth, G. C. 1964. Estimates of mean maximum mixing depths in the contiguous United States.
Mon. Weath. Rev. 92: 235-242.
16
393
394
395
Lefohn, A., Emery, C., Shadwick, D., Wernli, H., Jung, J., and S. Oltmans. 2014 Estimates of background
surface ozone concentrations in the United States based on model-derived source apportionment.
Atmos. Environ. 84: 275-288, doi:10.1016/j.atmosenv.2013.11.033.
396
397
Midwest Ozone Group. 2013. Air Trends Project. http://midwestozone group.com/Air Trends July
2013Public.html (accessed December 8, 2014).
398
399
400
Tong, D. and D. Mauzerall. 2008. Summertime State-level Source-Receptor Relationships between
Nitrogen Oxides Emissions and Surface Ozone Concentrations over the Continental United States.
Environ. Sci. Technol. 42: 7976-7084.
401
17