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# Assessment of Qualification for Treatment under the Arizona Natural and Exceptional

Events Policy for the High Particulate (PM 10 

# ) Concentration Events in the

Phoenix and Yuma Areas on May 21, 2008

Background

The Arizona Department of Environmental Quality (ADEQ)

issues Dust Control Action Forecasts for the Yuma and

Phoenix areas as part of their Natural Events Action Plans.

On Tuesday May 20, 2008, in response to an approaching

trough of low pressure, ADEQ ai r quality forecasters issued

the Maricopa County Dust Control Action Forecast calling for

a high risk of wind-blown dust for Wednesday May 21 st 

### , in

Maricopa County. In anticipatio n of this potential wind-blown

dust event, ADEQ also issued a High Pollution Advisory for

Maricopa County for May 21, 2008. The approaching trough

was forecast to impact the Yuma area as well, and ADEQ air

quality forecasters subsequently called for a high risk of

wind-blown dust in their Yuma and Vicinity Dust Control

Action Forecast fo r Wednesday, May 21 st 

### . This potential

regional high-wind event equated to a significant risk of

exceeding the PM 10 

### National Ambient Air Quality Standards

(NAAQS) in both Yuma and Mari copa County. The forecasts/

advisories satisfy the requirem ent in 40 CFR 51.930(a)(1).

The forecast for May 21 st 

### for both Maricopa County and

Yuma called for sustained winds at 20-30 mph with the

possibility of gusts greater than 40 mph capable of producing

significant wind-blown dust. This potential wind-blown dust

event equated to a high risk of exceeding the PM 10 

### NAAQS in

Maricopa County. Strong winds did occur and were observed

in the Phoenix Metro and the Yuma areas on May 21 st 

### , 2008.

Beginning in the morning and continuing through the evening

hours of May 21 st 

### , strong southwesterly and westerly winds in

Phoenix and strong west-north westerly winds in Yuma

generated areas of blowing du st. All appropriate State Implementation Plan (SIP) control measures were in place

during the event, demonstrating per 40 CFR 50.1(j) that the

event “is not reasonably controllable or preventable.” A

discussion of commonly employ ed Best Available Control

Measures (BACM) for dust in Maricopa and Yuma counties

can be found in “High Wind Exceptional Events and Control

Measures for PM 10 

### Areas” (see “References”).

The initialization of a wind-blown dust event is evident in the

Phoenix visible camera images, as well as the Arizona

Meteorological Network (AzM ET), Maricopa County (MC),

ADEQ, and National Weather Se rvice (NWS) monitors (see

Fig. 1). Strong winds gusting over 25 mph and as high as 35

mph at the MC West 43 rd 

### monitor location and 37 mph at the

NWS Luke Air Force Base were reported. The Yuma Marine

Corps Air Stations (MCAS) also measured wind gusts up to

37 mph along with reports of reduced visibility. This

significant wind event brought elevated ambient

concentrations of PM 10 

### to the Phoenix and Yuma areas that

exceeded the NAAQS at the West 43 rd 

### Ave. and Yuma

Courthouse monitors. Due to the spatial variability of PM

sources both within and outside of the Phoenix urban core, the

PM 10 

### NAAQS was only exceeded at the West 43 rd 

### monitors

operated by Maricopa County, though other Phoenix area

monitors did show elevated levels of PM 10 

### (see Section 2 for

more detail). The fact that ambient concentrations exceeded

the NAAQS satisfies th e criteria in 40 CF R 50.1(j) that the

event “affects air quality.” The following are the key PM 10 

### monitor readings for the monitors examined in this report:

Monitor (Operator/Type) AQS ID 24-hr Avg PM 10 

### 1-hr Max PM 10 

### Max Time Flag**

YUMA AREA

Yuma Courthouse (ADEQ/TEOM) 04-027-0004* 164 504 1700 RJ

PHOENIX METRO AREA

West 43 rd 

### Ave (MC/TEOM) 04-013-4009* 279 1208 0900 RJ

Durango Complex (MC/TEOM) 04-013-9812* 110 310 0900 None

Greenwood (MC/TEOM) 04-013-3010* 89 219 0900 None

South Phoenix (MC/TEOM) 04-013-4003* 122 334 0900 None

* EPA Air Quality System Identification Number

** 24-hr PM 10 concentration influenced by natural or exceptional event to be flagged.

Type Abbreviations: TEOM – Tapered Element Oscillating Microbalance Monitor (Continuous monitor).



### The preliminary findings from this analysis were presented at

stakeholders meeting on Nove mber 19, 2008, and March 19,

2009, in Phoenix, Arizona. Following the stakeholders

meetings, ADEQ supplemented and finalized the analysis and a public comment period was held from October 15, 2009

through November 13, 2009. This finalized document and

any comments received are being submitted to EPA to satisfy

the requirements in 40 CFR 50.14(c)(3)(i).HrT(F) PM Spd Max Dir HrT(F) PM Spd Max Dir HrT(F)VRDustSpdGustDir Hr1 21 89879 21 SW1 91294 15W1 84 10 14 14 SW187 512 87469 19 SW2 88396 18W2 80 10 13 13 SW247 673 85405 11 SW3 87414 15W3 79 10 15 15 SW340 714812827W48526210SW479101414S429 395 82323 14 S 5 83312 9SW5 75 10 7 7 SW532 496 82604 9 S 6 84272 14 S 6 75 10 10 10 Swithw/o660 587 83542 9 S 7 86275 13 S 7 77 10 11 11 SWMonitor:Event Event755 678 8613510 21 SW8 88304 15 SW8 81 10 17 17 SW1-W43RD279668135 849 8851815 29 SW9 90446 19 SW9 85 10 20 20 SW2-YUMAC164769519 17810 89120718 32 SW10 8933410 30W10 86 10 23 23 SW101208 17111906001730W1190159923W1187102130SW> NAAQS< NAAQS11601 19612924131529W12911391126W1289102128SW12413 1921 9453415 34 SW1 9320511 32W1 91 10 9 34 SW1535 1922 9483617 35W2 9330014 34W2 91 10 26 37W2837 1603 9473519 34W3 9328616 31W3 91 10 20 31W3735 1404 9425416 30W4 9328016 32W4 91 10 22 29W4255 1615922241630W5921931430W589101733W5225 467wnd@3m agl/Dir correctedtotrue north6902431532W6911671428W688102025W6243 504HIGHLIGHTINGCol.Parameter7 8726216 31W7 8919814 29W7 85 10 21 26 SW7263 210Max Wind T(F)Temp.(Deg. F.)8 8410412 22W8 861129 27W8 83 10 16 16W8105266> 15 mph RHRel Humidity%982761120W98483822W982101616W977175>25mphRnRain(Inches/hr)10 80698 17W10 82585 14W10 81 10 18 18 NW1069168HR - Time (End) SpdAvgSpeed mph11 785810 21W11 81577 20W11 78 10 9 9W1158 139A.M. MaxMax Speed mph127769816SW12796339W1278101313W1270 140P.M.DirWind Dir.(from)5/21-2:00AM5/21-8:00AM5/21-9:00AM5/21-10:00AM5/21-4:00PMHr T(F) RH PM Spd Max Dir Hr T(F) PM Spd Max Dir Hr T(F) PM Spd Max Dir1 82 25409 14 SW1 89267 20 SW1 88458 21 SW2 81 25413 12 SW2 874110 26 SW2 864310 21W3753249414W38548718SW38546919W472364715E48335413SW48141613SW574332949SW58030412SW58037716SWYrSea YrSea6 73 36337 11 SW6 81334 12 SW6 80516 15 S 5 8 8 8 5/21 - 9:30AM 5/21 - 1:30PM 5/21 - 2:30PM 5/21 - 3:30PM 5/21 - 7:30PM7 73 38424 11 SW7 82454 11 SW7 81504 12 S9 9 12 98 80 315310 23W8 84552 15W8 85568 18 SW11 11 14 149 83 258216 26 SW9 87801 99 SE 9 8913111 27 SW15 13 16 1610 85 2620019 32 SW10 971414 32 SW10 8830916 32W19 19 19 1911 88 249118 29 SW11 8610913 30 SW11 8817116 31W29 28 23 221291201751530W1288911335W12911151429W444631291 91 1551918 33W1 9011312 33W1 9213114 31W65 63 42 402 92 1439020 34W2 9115214 34W2 9224617 32W91 82 57 513 92 1319717 34W3 9116013 32W3 9323117 35W121 107 77 764 91 1323516 35W4 9015914 33W4 9216217 31W139 125 96 109 5/21 - 9:30AM 5/21 - 1:30PM 5/21 - 2:30PM 5/21 - 7:30PM5 90 1321516 30W5 9013413 31W5 9113315 29W157 134 127 1826 88 1314316 29W6 8812911 28W6 8913615 30W192 194 186 2107 85 159914 24W7 8711213 27W7 8712216 29W227 220 211 21288116641219W884931125W8831061325W3133133493499 77 20779 14W9 827110 22W9 819211 20W10742346914W108062716W108065918W11 73 22428 15W11 80478 19W11 78649 18W127321471017W127831413W127656512W5/21-9:30AM5/21-1:30PM5/21-7:30PMHr T(F) RH Spd Max Dir Hr T(F) RH Spd Max Dir Hr T(F) VRDustSpdGustDir Hr T(F) RH Rn Spd Max Dir1 71 35 2 5 SE1 81 16 9 19W1 82 10 0 0 N1 78 19 - 7 18W2 68 41 1 4W2 74 25 4 13 S 2 81 10 7 7W2 73 28 - 4 13 SW3 64 52 2 7 SE 3 71 28 5 13 S 3 77 10 6 6 S 3 68 34 - 3 8 SW4 63 51 3 6 S 4 72 28 7 12 SW4 77 10 3 3 SW4 68 37 - 5 8 SW5 65 47 0 4W5 65 43 4 9 SW5 74 10 5 5 SW5 62 54 - 2 6 SW5/21 - 9:30AM 5/21 - 1:30PM5/21 - 7:30PM6 65 43 3 9 SW6 69 37 6 9W6 75 10 9 9W6 64 53 - 4 6 SW7 68 40 3 9 S 7 69 38 5 11 SW7 76 10 5 5W7 67 47 - 4 13 SW8 76 34 6 15W8 77 31 13 24W8 81 10 13 13W8 77 32 - 11 21 NW9 79 31 7 17W9 78 32 15 25 NW9 83 10 14 23 NW9 78 32 - 13 20 NW10 80 30 8 20W10 79 31 15 25 NW10 85 10 16 24 NW10 80 31 - 13 20 NW11 82 28 8 23W11 81 30 16 25W11 87 10 16 16 NW11 82 30 - 15 23 NW1284261126W1283261627W128991826W128327-1524NW1 85 24 10 25W1 85 22 14 22W1 92 9 14 25 NW1 86 23 - 13 23 NW2 87 21 10 24W2 87 19 13 23W2 93 10 16 25W2 87 20 - 12 19 NW3 89 16 9 22W3 88 16 14 25 NW3 95 10 17 24 NW3 89 17 - 13 22 NW5/21 - 9:30AM 5/21 - 1:30PM5/21 - 7:30PM4 89 16 12 31W4 89 15 15 27W4 95 10 20 30W4 89 16 - 14 22 NW5 87 20 17 33W5 86 20 20 35W5 91 4 BLDU29 37W5 86 21 - 20 31W6 83 23 13 29W6 83 23 20 36W6 87 4 BLDU26 33W6 82 24 - 20 31W7 80 26 18 31W7 81 25 17 32W7 83 9 21 29W7 81 26 - 17 23WNo image available8 76 30 15 27W8 78 28 20 28W8 80 9 21 28W8 77 30 - 16 26 NW9 73 34 13 24W9 75 32 14 25W9 77 10 18 28W9 74 34 - 13 21W10 71 36 11 24W10 73 33 16 25W10 76 10 18 26W10 73 34 - 14 21 NW11 69 36 12 21W11 73 31 21 32 NW11 75 10 16 28W11 72 32 - 15 24 NW126837919W1272302033NW1274101515W127231-1625NWPrepared by S. Kendall, A. Juniel, B. Busby and B. Paris/ ADEQ 3/19/09MC - WEST PHOENIX

MC - WEST PHOENIX16477 (112.14Wx33.48N) 16375 (112.12Wx33.43N)MC - DURANGO COMPLEX

MC - DURANGO COMPLEX19040 (114.63Wx32.61N)ADEQ - YUMA MESA

ADEQ - YUMA MESANWS-Yuma MCAS16659 (112.14Wx33.41N)MC - WEST FORTY THIR

MC - WEST FORTY THIR21525 (112.62Wx33.37N)MC - BUCKEYE

MC - BUCKEYE16377 (112.08Wx33.40N)MC - SOUTH PHOENIX

MC - SOUTH PHOENIXWx IMAGERYPHX VIS.CAMERASHourly PM10Conc. (μg/m3)1-W43RDWINDS& PM10DATAECAHISTDISTPM10 &WIND PLOTAZMET Monitoring LocationsFigure 1.Key Data forEvent of May21, 2008KEY164Mon 225% 02-YumaValleySUMMARY OF EVENTBetween 7:00 a.m. and noon,gusts in the Valley were notedfrom the south to southwestbetween 26 to 29 mph at fiveNWS sites at 9:00 a.m. At 10:00a.m., winds were from thesouthwest to west with gustsup to 33 mph.

GOES-West Satellit eSee http://ag.arizona.edu/azmet/

NWS-Luke AFBPink=Event Contrib.Conclusion: Asshown above,the PM10concentration wouldhave been below theNAAQS "BUT FOR"the eventcontribution (hourshighlighted in pink).

ADEQ - YUMA AGRI CENADEQ - YUMA AGRI CEN128530 (114.71Wx32.71N)5%NWS-Luke AFB

NWS-Yuma MCAS27924-Hr. Avg PM102-YUMA CHMONITORS:Event Contrib. AnalysisMinHistorical Distribution5-Yr. Dist. of Values (μg/m3)Conclusion: Flagged Value is exceptionalYr - All Data(5-Yrs)1.0%0.5%10%75%99.5%99.0%90%FlaggedValueColumn IndexMaxCum. Mon 1Sea - Data for Springseason only(5-Yrs)in nature (ie greater than 95% of all data)95%97.5%AZMET - YUMAMONITORS:2.5%1-WEST FORTY THIR2-YUMA COURTHOUFreq.50% (looking south)

WHITE TANK MTN (looking west)

ESTRELLA MTN (looking south)5/21 - 3:30PM

CAMELBACK MTN (looking northeast)5/21-2:30PM5/21-3:30PM5/21 - 3:30PM

SUPERSTITION MTN (looking east)5/21 - 2:30PM 5/21 - 3:30PM5/21 - 2:30PM

SOUTH MOUNTAINWest 43rd - PM 10 vs. Wind Speed0200400600800100012001400 0:00 1:00 2:00 3:00 4:00 5:00 6:00 7:00 8:00 9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00 22:00 23:005/21/2008

PM Concentration ( μ g/m^3)0510152025303540 Wind Speed (mph)PM10Max Wind

## Assessment of May 21, 2008 event (Cont.)

- 4 - 

# Assessment under the Technical Criteria Document (TCD)

1. Properly qualify and validat e the air quality measurement

to be flagged. As this was not a filter sampling date (1-in-6

run day), only data from the continuous analyzers were

examined. The air quality monitoring data were reviewed by

the agency responsible for op eration of the monitor. All

hourly PM 10 

### readings from the West 43 rd 

### Ave. and Yuma

Courthouse monitoring sites were valid for May 21 st 

### . Audits

of the analyzers revealed operations were within acceptable

tolerance.

2. Review suspected contributing sources. On May 21, 2008,

strong westerly to southwesterl y winds were occurring in the

Phoenix area due to a low pressure system approaching from

the west with a cold front passing over Arizona. The high

wind event was a regional phenomenon that affected the

entire Phoenix Metro area as well as Yuma. However, PM

sources are highly variable across space; therefore, the

locations of higher PM 10 

### concentrations in Phoenix (namely

the Salt River channel) are likely an indication that these

locations (or areas upwind of these locations) contain greater

sources of PM than other lo cations within the Phoenix

Metropolitan area. While no specific source allocation can be

determined for this particular day, the 2005 ADEQ revised

PM 10 

### SIP for the Salt River area (attached) contains modeled

source contributions on high wi nd days (see section 4.2 –

Source Categories). Results est imate that approximately 76%

of PM 10 

### concentrations can be attr ibuted to windblown dust,

of which 21% is from agricultural fields, 15% from alluvial

channels, and 21% from vacant lots. It is not clear whether

similar source allocations can be assumed for this April 30,

2008, high wind event (see att achment for likely PM sources

within the Salt River area). PM 10 

### concentrations also spiked at

the Yuma Courthouse monitor between 8:00 a.m. and 9:00

p.m., roughly coincident with the spikes recorded at the West

43 rd 

### Ave. monitor. The plot of hourly PM 10 

### concentrations

and max wind data in the upper right corner of Figure 1

confirms the nearly identical timing of the elevated PM 10 

### concentrations and strong wind gusts recorded at the West

43 rd 

### Ave monitor.

3. Examine all air quality monitoring information. Data from

all monitors in the network we re reviewed. Monitors from

the affected areas are summarized in the table in the

Background section of this asse ssment. Pursuant to 40 CFR

50.14(c)(3)(iii)(C), the “Historical Distribution” Table in

Figure 1 has been included to demonstrate that the event is

associated with a measured concentration in excess of normal

historical fluctuations, including background (i.e.,

concentrations greater than the 95 th 

### percentile). Additionally,

the winds associated with the elevated PM 10 

### concentrations

may be characterized as unusual as described in “Impact of

Exceptional Events’ ‘Unusual Winds’ on PM 10 

### Concentrations” (see “References”). 4. Examine the meteorological conditions before and during

the event. The NWS, MC, ADEQ and AzMET surface data

for Arizona, along with the visibl e camera images in Phoenix,

provide a good explanation as to what meteorological

conditions were in place on May 21 st 

### . The meteorological

data are summarized in Figure 1. The wind data are

highlighted yellow if the max wind speed in the hour exceeds

15 mph and orange if it exceeds 25 mph. As can be seen in

Figure 1, wind speeds did not pick up in central and southern

Arizona until approximately 8:00 a.m., when several stations

reported gusty winds over 20 mph. This timing corresponds to

the onset of elevated PM 10 

### concentrations recorded at the

West 43 rd 

### Ave. and Yuma Courthouse monitoring sites, both

of which remained elevated through the afternoon and into the

evening.

5. Perform a qualitative attr ibution to emission source(s). All

evidence indicates the elevated PM 10 

### concentrations in the

Phoenix area can be attributed to soil emissions that were

transported over portions of the Phoenix Metro area in

Maricopa County. While it is possible that local soil sources

may have contributed to the West 43 rd 

### Ave. monitor being the

only one to exceed the NAAQS in the Phoenix Metro area, no

source specific emission allocat ion is possible based on the

data available for analysis. Th e hourly concentration data do

not show any significant sour ce other than the wind-blown

dust event occurring on May 21, 2008. Visual evidence of

reduced visibility can be seen in the images located in the

lower right portion of Figure 1. In the Yuma area, visibility

was reduced to 4 miles and blowing dust was reported by

trained weather spotters at the Yuma MCAS during the late

afternoon and early evening hour s. Yuma radar data also

suggests that blowing dust wa s occurring in southeastern

California and southwestern Ar izona (see attachment).

6. Estimation of Contribution from Source or Event. The

demonstration analysis contained in this report establishes the

linkage between the measuremen ts to be flagged and the

event, thus satisfying the requirement in 40 CFR

50.14(c)(3)(iii)(B). Pursuant to 40 CFR 50.14(c)(3)(iii)(D),

the “Event Contrib. Analysis” Table in Figure 1 has been

included to demonstrate that there would have been no

exceedances or violations but for the event (i.e., the

contribution during the event overwhelmed the 24-hour

averages).

7. Determination that a Natural or Exceptional Event

Contributed To an Exceedance. Based on this analysis, the

event satisfies the requirement in 40 CFR 50.1(j) that the

elevated concentrations at West 43 rd 

### Ave. and the Yuma

Courthouse were attributed to a natural event.



# Conclusion

Transport of dust from soils by high winds . The region wide

elevated PM 10 

### event on May 21, 2008, in Yuma and Maricopa

Counties was the result of the transport of dust and soils from

winds that suspended natural so ils and soils from areas where

Best Available Control Measures are in place and should be flagged for air quality planning purposes. The “high wind”

(RJ) flag should be applied to the monitor readings indicated

in the table at the beginning of this report, as the monitor

would have been below the NA AQS but for the contribution

of the event.

# ATTACHMENTS AND REFERENCES

FOR EXCEPTIONAL EVENTS ANALYSIS

The following are supplemental materials helpful in understanding the exceptional

event summarized in the main report. In addition, the reader is referred to the

following references.

REFERENCES

Arizona Department of Envi ronmental Quality (ADEQ), Air Quality Exceptional and

Natural Events Policy , Policy Number 2009.002 (April 28, 1999; revised January 10,

2006 and June 22, 2007).

Arizona Department of Environmental Quality (ADEQ), Technical Criteria Document

for Determination of Natural Exceptional Events for Particulate Matter Equal to or Less

Than Ten Microns in Aerodynamic Diameter (PM 10 

# ) (May 31, 2000).

Arizona Department of Environmental Quality (ADEQ), Technical Criteria Document

for Determination of Na tural and Exceptional Events (December 12, 2005).

Arizona Department of Environmental Quality (ADEQ), Impact of Exceptional Events

‘Unusual Winds’ on PM 10 

# Concentrations (October 14, 2009).

Arizona Department of Envi ronmental Quality (ADEQ), High Wind Excep tional Events

and Control Measures for PM 10 

# Areas (October 14, 2009).

Environmental Protection Agency (EPA), The Treatment of Data Influenced by

Exceptional Events (Exceptional Event Rule) , 73 FR 70597; 40 CF R Parts 50 and 51

(November 21, 2008).

### VERY UNHEALTHY (201-300)

UNHEALTHY (151-200)

UNHEALTHY FOR SENSITIVE GROUPS (101-150)

MODERATE (51-100)

GOOD (0-50)

For more information visit:

http://www.epa.gov/airnow/aqibroch

NEW!!! CLICK HERE FOR UPDATED 2008 OZONE SEASON STATS NEW!!!



# AIR QUALITY FORECAST FO R WEDNESDAY, MAY 21, 2008

This report is updated by 1:00 p.m. Sunday thru Friday and is valid

for areas within and bordering Maricopa County in Arizona

* O3 = Ozone CO = Carbon Monoxide PM-10 = Particles 10 microns & smaller PM-2.5 = Particles smaller than 2.5 micro ns

*“ Ozone Health Watch ” means that the highest concentration of OZONE may approach the federal health standard.

“ PM-10 or PM-2.5 Health Watch ” means that the highest concentration of PM-10 or PM-2.5 may approach the federal health standard.

“ High Pollution Advisory ” means that the highest concentrati on of OZONE, PM-10, or PM-2.5 may exceed the federal health standard.

“ DUST ” means that short periods of high PM-10 concentrati ons caused by outflow from thunderstorms are possible. 

## FORECAST

DATE

NOTICES

(*SEE BELOW

FOR DETAILS)

AIR POLLUTANT 

## YESTERDAY

MON 05/19/2008

OZONE HEALTH

WATCH

NWS EXCESSIVE

HEAT WARNING

Highest AQI Reading/Site

(Preliminary data only) 

## TODAY

TUE 05/20/2008

OZONE HIGH

POLLUTION

ADVISORY

NWS EXCESSIVE

HEAT WARNING 

## TOMORROW

WED 05/21/2008

PM-10 HIGH

POLLUTION

ADVISORY

OZONE HEALTH

WATCH

NWS WIND

ADVISORY 

## EXTENDED

THU 05/22/2008

PM-10 HEALTH

WATCH

POSSIBLE

DUST



# O3* 97

TONTO NATIONAL

MONUMENT 

## 124

UNHEALTHY

FOR SENSITIVE

GROUPS 

## 93

MODERATE 

## 80

MODERATE



# CO* 14

PHOENIX SUPERSITE 

## 09

GOOD 

## 06

GOOD 

## 06

GOOD



# PM-10* 80

WEST FORTY THIRD 

## 74

MODERATE 

## 140

UNHEALTHY

FOR SENSITIVE

GROUPS 

## 92

MODERATE



# PM-2.5* 44

DURANGO 

## 32

GOOD 

## 53

MODERATE 

## 55

MODERATE

## Health message for Tuesday, May 20: Active children and adults, and people with

lung disease such as asthma, should reduce prolonged or heavy outdoor exertion.

Health message for Wednesday, May 21: Active children and adults, and people

with lung disease such as asthma, should reduce prolonged or heavy exertion.

Synopsis and Discussion

AN OZONE HIGH POLLUTION ADVISORY REMAINS IN EFFECT TODAY MAY 20

A PM-10 HIGH POLLUTION ADVISORY AND AN OZON E HEALTH WATCH HAVE BEEN ISSUED FOR

WEDNESDAY MAY 21



## Local ozone levels approached unhealthy levels at several east Valley locations on Monday, and as of

10:00 a.m. this morning hourly concentrations were running 10-15 parts per billion higher than 24 hours

ago at most monitoring sites; therefore, today’s High Pollution Advisory will continue thru the early

evening hours. All eyes now turn to the significant wind/blowing dust/unhealthy PM-10 (coarse particle)

event that is looking inevitable for Wednesday. A transition from record heat to below average

temperatures will begin on Wednesday as a surface cold front moves ove r the state ahead of an intense

upper level trough. A sharp temperature contrast will be reflected in tight pressure and contour gradients

that will be capable of producing sustained winds over 30 mph and wind gusts in excess of 40 mph over a

wide area, much of it open desert. The likelihood that widespread blowing dust will be generated by

afternoon has prompted the issuance of a PM-10 High Pollution Advisory. Under sunny skies and with

continuing additional ozone transport from California, local ozone levels could also be a concern. -Reith

MONITORING SITE MAPS: STATIC MAP

- http://www.azdeq.gov/environ/air/monitoring/images/map.jpg

INTERACTIVE MAPS - http://aqwww.maricopa.gov/AirM onitoring/SitePollutionMap.aspx

http://www.airnow.gov /



## POLLUTION MONITOR READINGS FOR MONDAY, MAY 19, 2008



# O3 (OZONE)

For facts on new 8-hr ozone standard go to: http://www.epa.gov/air/ozonepo llution/pdfs/2008_03_aqi_changes.pdf

For maps go to: http://www.airnow.gov/index.cfm?action=airnow.currentconditions

SITE NAME MAX 8-HR VALUE (PPB) MAX AQI AQI COLOR CODE

Alamo Lake (La Paz County) NOT AVBL NOT AVBL NOT AVBL

Apache Junction (Pinal County) 68 77

Blue Point 66 71

Buckeye 54 46

Casa Grande (Pinal County) 64 64

Cave Creek 66 71

Central Phoenix 62 58

Combs School (Pinal County) 57 48

Dysart 54 46

Falcon Field 67 74

Fountain Hills 67 74

Glendale 54 46

Humboldt Mountain 64 64

Maricopa (Pinal County) 55 47

North Phoenix 61 54

Phoenix Supersite 63 61

Pinal Air Park (Pinal County) 60 51

Pinnacle Peak 63 61

Queen Valley (Pinal County) 72 90

Rio Verde 70 84

South Phoenix 66 71

South Scottsdale 62 58

Tempe 64 64

Tonto Nat’l Mon. (Gila County) 74 97

West Chandler 61 54

West Phoenix 64 64

Yuma (Yuma County) 57 48

# CO (CARBON MONOXIDE)

SITE NAME MAX 8-HR VALUE (PPM) MAX AQI AQI COLOR CODE

Central Phoenix 0.9 10

Greenwood 1.1 13

Phoenix Supersite 1.2 14

West Indian School 1.0 11

West Phoenix 0.6 07



# PM-10 (PARTICLES)

SITE NAME MAX 24-HR VALUE (ug/m3) MAX AQI AQI COLOR CODE

Buckeye 47 44

Central Phoenix 41 38

Combs School(Pinal County) 59 53

Coyote Lakes 37 34

Durango 54 50

Greenwood 47 44

Higley 46 43

Maricopa (Pinal County) 74 60

Phoenix Supersite 33 31

South Phoenix 50 46

West Forty Third 113 80

West Phoenix 42 39



# PM-2.5 (PARTICLES)

(Some data derived from light-scattering equipment)

For maps go to: http://www.airnow.gov /

SITE NAME MAX 24-HR VALUE (ug/m3) MAX AQI AQI COLOR CODE

Durango 13.6 44

Dysart 4.3 14

Estrella Mountain Park 6.4 21

Phoenix Supersite 13.0 42

Vehicle Emissions Lab 6.2 20

West Phoenix 10.7 35

# LOCAL AIR POLLUTANTS IN DETAIL

O3 (OZONE) :

Description – This is a secondary pollutant that is formed by the reaction of other primary

pollutants (precursors) such as VOCs ( v olatile o rganic c ompounds) and NOx ( N itrogen Ox ides)

in the presence of heat and sunlight.

Sources – VOCs are emitted from motor vehicles, chemical plants, refineries, factories, and

other industrial sources. NOx is emitted from motor vehicles, power plants, and other sources of

combustion.

Potential health impacts – Exposure to ozone can make people more susceptible to respiratory

infection, result in lung inflammation, and aggr avate pre-existing respiratory diseases such as

asthma. Other effects include decrease in lung fu nction, chest pain, and cough.

Unit of measurement – Parts per billion (ppb).

Averaging interval – Highest eight-hour period within a 24-hour period (midnight to midnight).

Reduction tips – Curtail daytime driving, refuel cars an d use gasoline-powered equipment as late

in the day as possible.



## CO (CARBON MONOXIDE) :

Description – A colorless, odorless, poisonous gas formed when carbon in fuels is not burned

completely.

Sources – In cities, as much as 95 percent of all CO emissions emanate from automobile exhaust.

Other sources include industrial processes, non-transportation fuel combustion, and natural

sources such as wildfires. Pe ak concentrations occur in colder winter months.

Potential health impacts – Reduces oxygen delivery to the body’s organs and tissues. The health

threat is most serious for those who suff er from cardiovascular disease.

Unit of measurement – Parts per million (ppm).

Averaging interval – Highest eight-hour period within a 24-hour period (midnight to midnight)

Reduction tips – Keep motor vehicle tuned properly and minimize nighttime driving.



## PM-10 & PM-2.5 (PARTICLES) :

Description – The term “particulate matter” (PM) includes both solid particles and liquid droplets

found in air. Many manmade and natural sources emit PM directly or emit other pollutants that

react in the atmosphere to form PM. Particles le ss than 10 micrometers in diameter tend to pose

the greatest health concern because they can be inhaled into and accumulate in the respiratory

system. Particles less than 2.5 micrometers in diameter are referred to as “fine” particles and are

responsible for many visibility degradations such as the “Valley Brown Cloud” (see

http://www.phoenixvis.net/ ). Particles with diameters between 2.5 and 10 micrometers are referred

to as “coarse”.

## Sources – Fine = All types of combustion (motor vehicles, power plants, wood burning, etc.) and

some industrial processes. Coarse = crushing or grinding operations and dust from paved or

unpaved roads.

Potential health impacts – PM can increase susceptibility to respiratory infections and can

aggravate existing respiratory diseases, such as asthma and chronic bronchitis.

Units of measurement – Micrograms per cubic meter (ug/m3)

Averaging interval – 24 hours (midnight to midnight).

Reduction tips – Stabilize loose soils, slow down on dirt ro ads, carpool, and use public transit.

{ Updated 08/14/2007 }

# MARICOPA COUNTY

DUST CONTROL ACTION FORECAST

ISSUED TUESDAY, MAY 20, 2008

Three-day weather outlook:

tttttttttttttttttttt

R I S K F A C T O R S

In the wake of the heat wave on Monday and Tuesday the approach of an intense late-season trough in the mid-latitude storm

track will make for very windy conditions region-wide beginning on Wednesday. On that day a surface cold front will move

over Arizona ahead of the trough; both the duration and speed of the winds have the potential to produce widespread blowing

dust over the desert areas with a HIGH risk of unhealthy PM-10 levels in the Phoenix area; Hi gh Pollution Advisory will be

issued as a result. On Thursday and Friday somewhat less grad ient wind may be enhanced by thunderstorm downdrafts so the

risk level will remain elevated both days.



## WINDS STAGNATION RISK LEVEL

Day #1: Wed 05/21/2008



## + = Southwest to westerly

15-30 mph with gusts

near 40 mph possible. Rather stagnant during

the morning hours

with improvement by

afternoon. 

## HIGH

Day #2: Thu 05/22/2008 + = Southwest to westerly

15-25 mph with

stronger gusts near

thunderstorms. Little if any stagnation

expected.



## MODERATE

Day #3: Fri 05/23/2008 + = Southerly 15-25 mph

by afternoon with

higher gusts near

thunderstorms. Little if any stagnation

expected.



## MODERATE

The Maricopa County Dust Control Ac tion Forecast is issued to assist in the planning of work activities to

help reduce dust pollution. To revi ew the complete air quality forecas t for the Phoenix metropolitan area

and the health effects of air pollution, please see ADEQ's Air Quality Forecast at

http://www.azdeq.gov/environ /air/ozone/ensemble.pdf

, or call 602-771-2367 for recorded forecast

information.

# YUMA AND VICINITY

DUST CONTROL ACTION FORECAST

ISSUED TUESDAY, MAY 20, 2008

Three-day weather outlook:

tttttttttttttttttttt

In the wake of the heat wave on Monday and Tuesday the approach of an intense late-season trough in the mid-latitude storm

track will make for very windy conditions region-wide beginning on Wednesday. On that day a surface cold front will move

over Arizona ahead of the trough; both the duration and speed of the winds have the potential to produce widespread blowing

dust over the desert areas with a HIGH risk of unhealthy PM-10 levels in the Yuma area. Equally strong down-river winds are

possible on Thursday, enhanced by the possibility of thunde rstorm downdrafts.



## WINDS WIND-BLOWN DUST RISK

Day #1: Wed 05/21/2008 West to northwesterly

20-30 mph with gusts

over 40 mph possible

by afternoon. 

## HIGH

Day #2: Thu 05/22/2008 Northwest to northerly

20-30 mph with gusts

approaching 40 mph. 

## HIGH

Day #3: Fri 05/23/2008 Southerly 15-25 mph

with gusts to 30 mph

except stronger near

thunderstorms. 

## MODERATE

PM-10 & PM-2.5 (PARTICLES)

Description – The term “particulate matter” (PM) includes both so lid particles and liquid droplets found in air. Many

manmade and natural sources emit PM directly or emit other pollu tants that react in the atmosphere to form PM. Particles

less than 10 micrometers in diameter tend to pose the greates t health concern because they can be inhaled into and

accumulate in the respiratory system. Particles less than 2.5 mi crometers in diameter are referred to as “fine” particles and

are responsible for many visibility degradations (brown cl oud). Particles with diameters between 2.5 and 10 micrometers

are referred to as “coarse”.

Sources – Fine = All types of combustion (motor vehicles, power plants, wood burning, etc.) and some industrial

processes. Coarse = crushing or grinding operations and dust from paved or unpaved roads.

Potential health impacts – PM can increase susceptibility to respiratory infections and can aggravate existing respiratory

diseases, such as asthma and chronic bronchitis.

Units of measurement – Micrograms per cubic meter (ug/m3)

Averaging interval – 24 hours (midnight to midnight).

Reduction tips – Stabilize loose soils, minimize travel on dirt roads, utilize tarps on haul trucks, limit use of leaf-blowers,

and on high-wind days redu ce outdoor activities.

CKR 05/09/200505/21/2008 - ADDITIONAL GRAPHSWest 43rd - PM 10 vs. Wind Speed0200400600800100012001400 0:00 1:00 2:00 3:00 4:00 5:00 6:00 7:00 8:00 9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00 22:00 23:005/21/2008

PM Concentration ( μ g/m^3)0510152025303540 Wind Speed (mph)PM10Max WindDurango - PM 10 vs. Wind Speed0200400600800100012001400 0:00 1:00 2:00 3:00 4:00 5:00 6:00 7:00 8:00 9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00 22:00 23:005/21/2008

PM Concentration ( μ g/m^3)0510152025303540 Wind Speed (mph)PM10Max WindSouth Phoenix - PM 10 vs. Wind Speed0200400600800100012001400 0:00 1:00 2:00 3:00 4:00 5:00 6:00 7:00 8:00 9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00 22:00 23:005/21/2008

PM Concentration ( μ g/m^3)0510152025303540 Wind Speed (mph)PM10Max WindYuma Courthouse - PM 10 vs. Wind Speed0200400600800100012001400 0:00 1:00 2:00 3:00 4:00 5:00 6:00 7:00 8:00 9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00 22:00 23:005/21/2008

PM Concentration ( μ g/m^3)0510152025303540 Wind Speed (mph)PM10Max Wind Yuma MesaMax Wind Yuma Ag.Phoenix Area PM10and Meteorological MonitorsSource: US EPA, ADEQ, & Google EarthYuma Area PM10and Meteorological MonitorsSource: US EPA, ADEQ, & Google Earth

# May 21 st 

# 2008 Radar and Satellite Data

Radar data obtained from the National Oceanic and Atmosphe ric Administration’s

National Climatic Data Center in co njunction with MODIS satellite photography

obtained from NASA’s Rapid Response System allows for a visual reassessment of the

event. These data were downloaded as KMZ files and displayed using Google Earth

software. The overlay of the products clearly shows that much of the suspended dust

originated in southeastern Calif ornia and was transported to the east. It can be seen that

large sources of dust appear to come fr om the Imperial Sand Dunes of southern

California (also known as the Algodones Dunes) and other si milar dunes or open desert

areas to the southwest of the Salton Sea. Another common source of blowing dust

appears to be an area of open desert to the south / southeast of Yuma. While some of the

radar images are obscured by noise, the dust sources are still clearly visible.

Figure 1 - Radar data and MODIS satellite imagery sh ow a major source of bl owing dust located to

the southwest of the Salton Sea.

## Figure 2 – Right around the time of highest PM 10 

## concentrations and lowest visibilities in the Yuma

area, radar data show what are likel y high concentrations of blowing dust to the west / northwest of

Yuma. These returns (show n as purple colors) are likely indicative of blowing dust originating from

e Imperial Sand Dunes. th

# The MODIS satellite data are from the Terra satellite with 250 meter resolution an

bands 7, 2, and 1 to accentuate vegetation. Ligh ter tan areas are indi cative of open de

while darker b d use

sert

rown areas indicate areas of higher elevation or differing soil type

ompared to that of the open desert). Th e suspected PM sources are outlined in the

image below. (c

Figure 3 - Image courtesy of MODIS Rapid Response Project at NASA/GSFC displayed using

Google Earth software.

### 26 

# CHAPTER 4: OVERVIEW OF PM 10 

# CONTROL MEASURES

4.1 INTRODUCTION

Chapter 1.2.2 of this SIP ("Regulatory History of the Metropolitan Maricopa PM 10 

## Nonattainment

Area") notes that on July 25, 2002, EPA approved the Maricopa Serious PM 10 

## Nonattainment Area,

and granted Arizona's request, in accordance with CAA § 188(e), to extend the CAA deadline for

attainment of the annual and 24-hour PM 10 

## standards from December 31, 2001, to December 31,

2006 (67 FR 48718).

Because the attainment deadline for this plan revision is also December 31, 2006, and the

measures must be applied to all similar sources throughout the Phoenix Nonattainment Area (see

67 FR 44369, July 2, 2002), the control strategies mu st meet the "Most Stringent Measures" test, as

well as the “Best Available Control Measures/Technology” test. In its July 25, 2002, approval of the

Maricopa County Plan, EPA defined “most stringent measures” (MSMs) as the most stringent

measures included in any state implementation plan, or being implemented in any state, that are

economically and technologically feasible for the nonattainment area in question. “Best Available

Control Measures” (BACM) must be applied in serious nonattainment areas, also taking into

account the economic and technological feasibility of each measure.

This chapter details the proposed BACM and MSM that were evaluated for each significant source

category.

4.2 SOURCE CATEGORIES

The Salt River Study Area 2002 base year emissions inventory is described in Chapter 3.0 and the

TSD’s Chapter 4.0. The 2002 emissions source category contributions to ambient PM 10 

## are

depicted in Table 4.2.1. The average concentrations are derived from the modeled concentrations

outlined in the TSD, Chapter 6.

Assumptions used to calculate trackout emissions appear in Appendix K “Methodology for

Weighting Trackout Emissions” and Appendix P “Mapping Weighted Trackout Emissions into

Predicted Concentrations” of the October 2004 TSD. Calculation methodology for street sweeping

emissions reductions appears in Appendix L “Street Sweeping Reductions” of the October 2004

TSD.

Table 4.2.1 2002 Salt River Study Area Source Category Contributions to Ambient PM 10 

### Concentrations

Average Low Wind

Day Contribution Average High Wind

Day Contribution Highest

Contribution(μg/m 3 

### ) Source Category Percentage

Contribution Percentage

Contribution Low Wind

Day High Wind

Day

Industrial Sources 25.9% 8.3% 60.2 31.8

Point Emissions 2.7% 1.1% 5.3 3.0

Area Emissions 23.2% 7.2% 54.9 28.8

Construction 5.8% 0.9% 6.0 4.4

Area Sources 4.2% 0.7% 8.0 3.1

Unpaved Parking Lots 1.7% 0.2% 0.8 1.4

Unpaved Shoulders 2.5% 0.4% 7.2 1.7

### 27 Table 4.2.1 2002 Salt River Study Area Source Category Contributions to Ambient PM 10 

### Concentrations

Average Low Wind

Day Contribution Average High Wind

Day Contribution Highest

Contribution(μg/m 3 

### ) Source Category Percentage

Contribution Percentage

Contribution Low Wind

Day High Wind

Day

Roads & Trackout 63.7% 13.5% 73.6 42.7

Freeway 0.4% 0.2% 0.7 0.4

Primary Roads 43.6% 9.3% 44.8 33.3

Secondary Roads 7.5% 1.5% 6.9 1.5

Trackout 12.1% 2.5% 21.2 7.5

Agricultural Tillage 0.4% NA 0.2 NA

Windblown Dust NA 76.7% NA 290.1

Agricultural Fields NA 21.3% NA 84.9

Alluvial Channels NA 14.9% NA 79.5

Construction NA 3.5% NA 14.0

Industrial NA 7.3% NA 33.6

Disturbed Areas NA 5.2% NA 25.9

Stockpiles NA 3.6% NA 12.6

Vacant Lots NA 20.9% NA 39.6

Note: Bold concentrations exceed the 5 μg/m 3 

### threshold for significant sources.



## In Table 4.2.2, the modeled contributions for each of the source categories are given for the 2006

attainment case. These percentages are similar to the 2002 case, but with several significant

differences. For example, the windblown contribution decreases from 77% to 59% from 2002 to

2006.

Table 4.2.2 Salt River Study Area Source Category Contributions to Ambient PM 10 

### Concentrations for the 2006 Attainment Case

Average Low Wind Day

Contribution Average High Wind Day

Contribution Source Category

Percentage Contribution Percentage Contribution

Industrial Sources 29.7% 12.1%

Point Source Emissions 

### 4.4% 3.1%

Area Emissions 

### 25.2% 8.9%

Construction 5.2% 1.8 %

Area Sources 7.1% 2.1%

Unpaved Parking Lots 

### 0.5% 0.6%

Unpaved Shoulders 

### 6.6% 1.5%

Roads & Trackout 58.0% 24.7%

Freeway 

### 0.9% 0.4%

Primary Roads 

### 48.3% 21.6%

Secondary Roads 

### 6.8% 1.9%

Trackout 

### 2.0% 0.7%

Agricultural Tillage 0.1% NA

Windblown Dust NA 59.4%

Agricultural Fields 

### NA 8.9%

Alluvial Channels 

### NA 15.4%

Construction 

### NA 4.2%

Industrial 

### NA 6.7%

Disturbed Areas 

### NA 10.1%

Stockpiles 

### NA 5.9%

Vacant Lots 

### NA 8.4%