# Cache Valley Air Quality Studies

A Summary of Research Conducted
(through 2006)



### prepared by Dr. Randy Martin Department of Civil & Environmental Engineering Utah State University

UMC 4110 

### Logan, UT 84322 rmartin@cc.usu.edu

August 2006ii 

### EXECUTIVE SUMMARY

The Cache Valley airshed is in serious threat of exceeding the U.S. National Ambient Air Quality Standard (NAAQS) for Particulate Matter less than 2.5 μ m in diameter (PM 2.5 ). Although the local airshed appr oaches both the annual (15 μ g m -3 ) and the 24-hr standard (65

μ g m -3 ), it is the 24-hr standard that is in the greatest danger of exceedance. As of June 2006, the regulatory allowable 98 th percentile value for 2006, roughly the eighth highest value) can only be 33.2 μ g m -3 without exceeding the NAAQS. To da te, this value has been exceeded four times. For comparison, the target value was exceeded 6, 41, and 39 times in the years 2003, 2004, and 2005, respectively. It should also be noted that the U.S. EPA is currently considering lowering the 24-hr standard to 35 μ g m -3

.

The Cache Valley PM 2.5 is somewhat uniquely a wintertime problem, when low lying, persistent radia tion and subsidence inversions set up, trapping pollutants in the Valley for extended periods of time, allowing photoche mically-derived particulate material to become elevated. Chemical analysis by resear chers at Utah’s Divisi on of Air Quality and Air Monitoring Center, as well as Utah State University, have shown that 50-95% of the

PM 2.5 collected at the Logan site is composed of ammonium nitrate (NH 4 NO 3 ).

In order to understand the local pollutant behavior and identify the most appropriate remediation scenarios, seve ral sequential and parallel re search programs have been conducted by Dr. Randy Martin and others at Utah State University. This document summarizes these efforts and attempts to coalesce these studies into a single report.

1) PM Homogeneity - Statistically (95% CI), the Cache Valley is homoge neous with regard to PM 2.5 concentrations during invers ion episodes, although some site-to-site variation may

exist. The areas which trended lower in concentrations were the extreme southeast (Hyrum) and west (Mendon) portions of the Valley. As a par tial result of these studies, FRM regulated monitoring stations were established in Hyrum, UT, Amalga, UT, Prestion, ID, and Franklin, ID.

2) Valley Ambient Ammonia - Based on measurements at the Logan loca tion, the Valley’s wintertime formation of ammonium nitrate was found to be limited by th e availability of n itrate, specifically nitric acid (HNO 3 ). The ambient Logan wintertime NH 3 averaged (24-hr) 9.2 μg/m 3
(13.9 ppb). Furthermore, following these da ta, the Cache Valley was found to be

NH 3 -rich by a factor of approximately tw o. Comparisons of wintertime ambient NH 3 concentrations between the Valley’s ur ban area (Logan) and a rural location (Amalga), showed the rural area averaged ≈ 2.5 times the NH 3 of the urban site.

3) On-road Automobile Emissions - The study found that approximately 4.5% and 10.3% of the Valley’s vehicles would fail inspections tests for NO

x and VOCs, respectively, and that these vehicles were responsible for 25.4% and 47.8% of the vall ey-wide emissions. The study also foundiii that the majority of the vehicles that w ould fail would be older than 1996. As of 2004, vehicle registrations from the Utah Depa rtment of Motor Vehicles showed the percentage of vehicles that are 1996 or newer be 49.4%, and, therefore, eligible for I & M testing with the simpler on-board diagnostic (OBD) method.

4) Public & Student Phone Survey

-

5) Inversion Heights (dT/dz)

6) Indoor/Outdoor PM 2.5 Concentrationss

7) Wintertime Vertical Ozone Profile

8) VOCsiv Cache Valley on a “good” day (Feb. 25, 2002)

Cache Valley on a “moderate” day (Feb. 23, 2002: PM 2.5 ≈ 40 μg/m 3 )

Cache Valley on a “very bad” day (Feb. 16, 2004; PM 2.5 = 101.6 μg/m 3 ), viewed from adjacent 6300 ft asl ridge topv Installing a portable AirMetrics’ MiniVol PM 2.5 sampler

Recovering a temperature sensor form the ridge above Loganvi URG ammonia and acid gas denuder system installed at the Logan site

.

Passive ammonia samplers (with and without rain cap)vii Cache Valley on-road vehicle exhaust measuremnt

On-road “Red Day’ notification signage Main Street in Loganviii MiniVol samplers during indoor vs. outdoor studies

Teflon nozzle and tubing during ozone vertical profile flight (Feb. 9, 2006: 14:57) -- also note visible inversion layerix 

### ACKNOWLEDGMENTS

The investigators would like to thank the Stat e of Utah and Utah State University for partial funding under the Community/University Research Initiative (C URI) Grant program. Utah’s Department of Environmental Quality ’s Division of Air Qu ality (DAQ) and Air Monitoring Center (AMC) are also to be grat efully thanked for funding several different aspects of the studies described within this document. Additional funding for personnel and supplies was obtained through the Utah Water Research Laboratory (UWRL).

The authors would also like to thank B ob Dalley, Neal Olson, Dave McNeill, Brock LaBaron, Tyler Cruckshank, Bruce Allen, Ran Mc Donald, Joe Thomas, Cheryl Heying, and Rick Sprott for their cooperation in supplying eq uipment, comparative data, and expertise. Personnel from the Bear River Health Department were also instrumental in the research

described herein and are also owed a great deal of thanks and appreciation. Additional acknowledgements go to USU students Thomas Bradley, Hosam Jamal, and Demetrio Cabanillas for their participation in various aspects of this project.x 

### TABLE OF CONTENTS

EXECUTIVE SUMMARY ..................................................................................................... ii

ACKNOWLEGDEMENTS..................................................................................................viii

OVERALL INTRODUCTION................................................................................................ 1

VALLEY-WIDE PM 10 AND PM 2.5 SATUARATION (HOMOGENEITY) STUDY............ 2

CACHE VALLEY AMBIENT AMMONIA STUDIES ....................................................... 17

ON-ROAD VEHICLE EMISSIONS IN CACHE VALLEY (2004) .................................... 30

VERTICAL TEMPERATURE PROFILE MEASUREMENT............................................. 51

INDOOR/OUTDOOR PARTICULATE MA TTER IN THE CACHE VALLEY................ 59

WINTERTIME VERTICAL OZONE DISTRIBUTIONS.................................................... 67

REFERENCES ..................................................................................................................... . 781 OVERALL INTRODUCTION

The elevated wintertime levels of PM 2.5 in Utah’s Cache Valley have been the subject of concern since measur ements of the criteria pollu tant began in the spring of 2000. As shown in Table 1, the airshed has flirted with exceeding National Ambient Air Quality Standard, especially the 24-hr value (65 μ g m -3 ), since the first complete 3-yr

data set was obtained.

Table 1. Regulatory PM 2.5 values for Logan, UT (UDAQ, 2006).

Year Annual Average 24-hr

98 th Percentile

2001 15.6 μ g m -3 71.1 μ g m -3

2002 14.7 μ g m -3 58.4 μ g m -3

2003 8.4 μ g m -3 31.5 μ g m -3

3-yr Avg 13.0 μ g m -3 54.8 μ g m -3

2004 15.3 μ g m -3 101.5 μ g m -3

3-yr Avg 12.8 μ g m -3 63.8 μ g m -3

2005 13.0 μ g m -3 61.7 μ g m -3

3-yr Avg 12.1 μ g m -3 64.9 μ g m -3

2006 Allowable ---- 33.2 μ g m -3

Compositional research conducted by Utah ’s Division of Air Quality (DAQ) and Air Monitoring Center (AMC), as well as inve stigators at Utah Stat e University, showed that the bulk of the fine particulate mate rial consisted of ammonium nitrate (NH 4 NO 3 ) (UDAQ, 2006). During “typical” winter days, it was shown that average NH 4 NO 3 content accounted for 50-60% of the partic ulate material, on elevated days (> 65 μ g m -3 ),

the NH 4 NO 3 fraction approached 80-95%.

The discovery of the elevated levels of PM 2.5 in the Cache Valley motivated several research studies to identify th e dominant causes and potential areas of

remediation. These efforts are described with in this document. Specifically, this report summarizes research into Cache Valley’s PM 10 and PM 2.5 homogeneity, determination of ambient levels of gas-phase ammonia (NH 3 ) and it’s role in limiting particulate formation, local on-road vehicle emissions, lo cal attitudes toward potential particulate control scenarios, inversion heights, indoor vs. outdoor PM 2.5 concentrations, research into ambient (rural and urban) concentrations of volatile organic compounds (VOCs), and continuing research of vertical ozone profiles and indoor ammonia.

It should be noted that these research programs include funding through Utah’s DAQ and AMC, but also other sources including Utah State University, The Utah Water Research Laboratory, and the B ear River Health Department.2 

### VALLEY-WIDE PM 10 

### AND PM 2.5 

### SATURATION (HOMOGENEITY)

STUDIES

Contributing Authors

Dr. Randal S. Martin Dept. of Civil & Environmental Engineering Utah State University Logan, UT

Grant W. Koford Bear River Health Department Logan, UT3 INTRODUCTION



### Among the first projects studied in cooperation with the Utah’s Division of Air Quality and Utah St ate Universities Ai r Quality Research Group within the Department of Civil and Environmental Engineering (CEE) and the Utah Water Research Laboratory (UWRL) was the examination of the potential homogeneity of PM 10 

### , and then PM 2.5 

### , throughout the Cache Valley. The impe tus for this study began in the fall of 2001 with comparisons of ambient PM 10 

### and PM 2.5 

### as measured at the Smithfield, UT residence of Dr. Ra ndy Martin and those monitored by the DAQ at the Logan city sampling lo cation (approximately 11 kilometers apart). Figures 1 and 2 show the 2002 comparisons for PM 10 

### and PM 2.5 

### , respectively.

Figure 1. Comparison of Logan and Smithfield 2002 ambient PM 10 concentrations.

Figure 2. Comparison of Logan and Smithfield 2002 ambient PM 2.5 concentrations. 2002 Cache Valley PM 2.5 (Act. Conditions)

0 20 40 60 80 100 120 140 160 180

1/ 1 1/ 31 3/ 2 4/ 1 5/ 1 5/ 31 6/ 30 7/ 30 8/ 29 9/ 28 10/ 28 11/ 27 12/ 27μ

Smithfield Logan (DAQ) 2002 Cache Valley PM 10 (Act Conditions)

0 20 40 60 80 100 120 140 160 180

1/1 1/31 3/2 4/1 5/1 5/31 6/30 7/30 8/29 9/28 10/28 11/27 12/27μ

Smithfield Logan (DAQ)4 As is shown above, the concentrations tre nds and absolute values are very similar for both sites, including the elevated levels recorded dur ing the wintertime inversion episodes. When similar data for the 2003 cal endar year are include d, the correlation (R 2 )

between the two sites was 0.819 and 0.923 for PM 10 and PM 2.5 , respectively. Although not statistically quantifiable, visual examin ation of the plotted data, for both size fractionations, seem to show a slight positive (greater than) difference at the Smithfield location in the summer and a slight negative (less than) difference in the winter. This

could be a reflection of the somewhat more rural nature of the Smithfield location.

Cache Valley’s high, “official” wintertime PM 2.5 concentrations, as measured at the single Logan city sampling site, the similar PM 10 and PM 2.5 trends observed at the separate Smithfield locati on, the abundance of secondary material, and visual observations suggested that th e particulate pollution was likel y not an isolated problem centered around the Logan location, but more likely homogeneous throughout the Cache Valley. In order to investigate this hypothesis, five portable PM 10 samplers were deployed throughout the Valley and operated during the winter of 2002/2003. These samplers were further compared to the DAQ operated Logan location and a paired set of federal reference method (FRM) PM 10 and PM 2.5 samplers deployed at the Smithfield

site.

As will be further discussed in following sections, the preliminary study conducted in during the wint er of 2002/2003, at the (equipm ent) limited number of available sites, showed that the Valley’s PM 10 was statistically homogeneous across the compared locations. Although the data did s uggest overall ambient particle homogeneity, the unexpectedly low particulate concentrations during the examined winter (refer back to Table 1), the variability in the relationship between PM 10 and PM 2.5 , and the limited number of available samplers left it uncer tain as to whether the airshed was truly homogeneous with respect to PM 2.5 , particularly at levels above the NAAQS. In order to more fully investigate this question, fifteen portable PM 2.5 samplers were deployed throughout the Cache Valley and operated during the winter of 2003/2004. Also as before, two federal reference method (FRM) PM 2.5 samplers were also deployed, including the Logan UDAQ regulatory and the Smithfield PM 2.5 sampling sites.

METHODOLOGY

2002/2003 PM 10 Homogeneity (Saturation) Study

In an attempt to bracket typical wintertime conditions, the initial PM 10 homogeneity study took place from Octobe r 24, 2002 through February 26, 2003, with a nominal sampling frequency of every six days. The samples were targeted to run for 24 hours, midnight to midnight, on each of the samp le days. In addition to the Logan city sampling site (UTM 430309 E, 4619926 N, zone 12) , six additional sites were established throughout Utah’s Cache Valley. These sites were located 2.9 km ENE (USU Campus), 3.9 km S (Evan’s Farm/Nibley), 5.5 WNW (Cach e Valley Hunter Education Center), 9.55 km SSW (American Heritage West Center), 10.9 km N (Smithfield), and 17.1 km NW (Newton) of the Logan sampling location.

Five portable AirMetrics PM 10 MiniVol samplers (Airmetrics, 2004) were borrowed from the Division of Air Quality of Utah’s Department of Environmental Quality (DEQ). These instruments were depl oyed at all but the Smithfield location. At the time of the described study, equivalent PM 2.5 samplers were not available to the investigators. The MiniVol Samplers opera te via a battery-powered pump, which draws air through an impactor specifically-designed to separate the larger particle fraction (>10 μm), allowing the PM 10 material to be collected on a subsequent 47 mm Teflon filter. The filters were equilibrated at room temperature, in an air-tight desi ccator, and weighed on a 5-place (gram-based) balance pre- and post- exposure until triplica te weights within 0.05 mg were obtained.

The samplers are designed to operate at an actual flowrate of 5 Lpm, with flow controlled via a manually set rotameter. Prior to sampling, each system was calibrated using a soap-bubble meter and a calibrati on equation was developed relating local temperature and pressure and th e rotameter reading to the flow rate at actual conditions. For a given sampling run, the expected averag e temperature and pressure were estimated, the necessary rotameter setting for the requi red 5 Lpm (actual) was determined, and the flow was adjusted so that when the system ’s internal alarm initia ted the sampling period, the proper flowrate would be obtained. An on- board elapsed time counter registered the actual duration of any given sampling period (s ome runs were abbreviated due to battery failure), which when combined with the rota meter flowrate, was used to determine the sample volume.

At the Smithfield location, a paired set of PM 2.5 /PM 10 FRM Samplers (Andersen Instruments, RAAS 2.5-100) were operated by the investigators following the basic regulatory guidelines outlined in 40 CF R 50, Appendix L (40CFR50, 2003). The FRM samplers at the Logan site, the DEQ’s o fficial Cache Valley sampling location, were operated by DAQ and Bear River Health Depart ment (BRHD) personnel, who shared the collected data with the project investigators.

Furthermore, the comparability, and th e necessity of any potential correction factors, of the portable MiniVol samplers to the FRM samplers was examined via separate co-located sampling runs, in addi tion to the scheduled sampling periods. For this co-located investigation, the MiniVols were placed next to the Smithfield FRM samplers and each was operated as normal fo r four separate, 24-hour sampling periods.

2003/2004 PM 2.5 Homogeneity (Saturation) Study

As before, since Cache Valley’s PM 2.5 problem is generally limited to winter periods, the next phase of the particle saturation study took place from November 11, 2003 through February 27, 2004, with a nominal sampling frequency of every six days. A significant inversion, and accompanying PM 2.5 episode, took place January 7-24, 2005 and during this period, the samplers were ope rated every other day. The samples were6 410000 420000 430000 440000

UTM Easting (NAD27) 4600000 4610000 4620000 4630000 4640000 4650000 4660000 4670000UTM Northing (NAD27) Preston, ID

Cornish, UT

Clarkston Franklin, ID

Richmond

Newton Amalga

Smithfield Ballard
Junction

Mendon Logan USU Hunter Ed

Evan's
Farm ASF

Wellsville Hyrum UT-ID
Border targeted to run for 24 hours, midnight to midnight, on each of the sample days. In addition to the Logan city sampling site (UTM 430309 E, 4619926 N, zone 12), sixteen additional sites were established throughout th e Cache Valley. The a dditional sites were located in or near surrounding Utah commun ities of Wellsville, Hyrum, USU’s Animal Science Farm (ASF), USU’s Evan’s Farm , Mendon, Cache Valley Hunter Education Center (Hunter Ed), the Utah State Univ ersity campus (USU), Ballard Junction, Smithfield, Amalga, Newton, Clarkston, Richmo nd, and Cornish. Two sites were also

established on the Idaho side of the Cache Va lley, at the towns of Franklin and Preston. Figure 3 shows the various sites’ location in terms of UTM (NAD27) coordinates.

Figure 3. Relative Cache Valley sampling locations for the 20003-2004 PM 2.5 saturation study.

The fifteen portable AirMetrics PM 10/2.5 MiniVol samplers (AirMetrics, 2004) were obtained from the Air monitoring Ce nter (AMC) of Utah’s Department of Environmental Quality (DEQ). These inst ruments were deployed at all but the Smithfield location. The MiniVol samplers operate via a battery-powered pump, which draws air through an impactor specifically-designed to sepa rate the larger particle7 fraction (>2.5 μm), allowing the PM 10 or PM 2.5 (depending on the sample head) material to be collected on a subsequent 47 mm Teflon filte r. The filters were equilibrated at room temperature, in an air-tight desiccator , and weighed on a 6-place (gram-based) microbalance pre- and post-exposure until tr iplicate weights within 0.005 mg were

obtained.

The samplers are designed to operate at an actual flowrate of 5 Lpm, with flow controlled via a manually set rotameter. Pr ior to testing, each system was calibrated using a soap-bubble meter and a calibrati on equation was developed relating local temperature and pressure and th e rotameter reading to the flow rate at actual conditions. For a given sampling run, the expected averag e temperature and pressure were estimated, the necessary rotameter setting for the requi red 5 Lpm (actual) was determined, and the flow was adjusted so that when the system ’s internal alarm initia ted the sampling period, the proper flowrate would be obtained. An on- board elapsed time counter registered the actual duration of any given sampling period (s ome runs were abbreviated due to battery or pump failure, programming errors, etc.) wh ich, when combined with the calibrated rotameter flowrate, was used to determine the sample volume.

At the Smithfield location, a PM 2.5 FRM sampler (Andersen Instruments, RAAS 2.5-100) was operated by the investigators fo llowing the basic regulatory guidelines outlined in 40 CFR 50, Appendix L (40CFR50, 2003). The PM 2.5 FRM (Rupprecht and Patashnick) sampler at the Logan site, the DEQ’s official Cache Valley sampling location, was operated by DAQ and BRHD personnel, who shared the co llected data with the project investigators.

Once again, the comparability, and the n ecessity of any potential correction factors, of the portable MiniVol samplers to the FRM samplers was examined through four separate co-located test runs. For the co-located inve stigations, the MiniVols were placed adjacent to and at the same elevati on as the Logan FRM sampler and operated to concurrent time periods.

RESULTS AND DISCUSSION

2002/2003 PM 10 Homogeneity (Saturation) Study

Co-location of the MiniVol samp lers with the Andersen FRM PM 10 sampler showed the portable samplers c onsistently reported higher PM 10 concentrations for all of

five of the individual instruments. The overa ll average error was found to be +27%. As can be seen in Figure 4, the test ed MiniVols over predicted the PM 10 concentrations by approximately 15-40%. Given the magnitude of these percentages and the relative tightness of their individual confidence interval s, the final data anal ysis calculations for the describe saturation study included the appropriate individual instrumentation

correction factors.8 30.9

26.9 39.0

18.9

15.4

0 5 10 15 20 25 30 35 40 45 50

1414 1415 1408 1409 1424

Sampler IDAverage % Error

Figure 4. Average percent error for the tested Mi niVol samplers when compared to a colocated FRM PM 10 sampler (error bars represent the 95% confidence interval).

A total of 18 sampling days were obs erved for the period between October 24, 2002 and February 26, 2003 for the PM 10 homogeneity study. Out of a potential total sample number of 126 samples (18 sample days x 7 sample sites), 13 (10.3%) individual samples were not obtained due to sampler failure or operator error. Typical explanations included battery failure or e rrors in setting of the on-boa rd timer/alarm. Typical PM 10 concentrations observed, as measured at the Logan city site, varied from 4 to 34 μg m -3

.

Although some day-to-day variations were observed in the geographical location

of PM 10 maximums, on average, the Cache Valley appeared to be quite homogeneous in terms of relative concentrations. However, at the 95% confidence le vel, the site located to the north of the Logan city ce nter did show slightly lower PM 10 concentrations, while

the site at the south end of Cach e Valley showed slightly higher PM 10 concentrations. Figure 5 shows the overall average site-to-site PM 10 concentration variations normalized

to the PM 10 concentrations measured at the Loga n (FRM) site. In other words, on any given day, the PM 10 concentration at any particul ar site was divided by the PM 10 concentration measured at the Logan site. Th is approach was used to minimize potential biases when averaging all of the individual sites’ data (e.g. not allowing differences on “low” days to be overshadowed by variations on “high” days). Although distinct trends can be seen in Figure 5, with inclusion of th e 95% confidence intervals (error bars), the overall data set shows statistically homogeneous concentrations. For example, error bars9 0.0 0.5 1.0 1.5 2.0

Logan Smithfield Hunter

Education

Center Evan's Farm Newton American Heritage

West USUAvg Site PM10Normalized to Logan PM10 for the Smithfield and American Heritage West (AHW) concentrations overlap the

Newton PM 10 concentration error bars, which, in turn, overlap all of the remaining sites. However, the Smithfield and AHW erro r bars do not overlap, so their PM 10 concentrations are statistically different from each other.

Figure 5. Average PM 10 concentrations normalized to the observed Logan PM 10 (error bars represent the 95% confidence interval).

Figure 6 shows the average normalized con centrations in relation to the sampling sites geophysical location. The contours were prepared via Golden Software’s Surfer mapping software using a Kriging algorithm. As can be seen, on average there appears to

be an identifiable increase in PM 10 concentrations when movi ng from the northern end of Cache Valley to the southern end.

Paired PM 10 and PM 2.5 samplers were only operated at the Logan and Smithfield locations. From these data, it was found that the PM 2.5 concentrations were an average of 67.5% ± 6.7 (±95% CI) of the PM 10 concentrations. More in terestingly, the Smithfield

PM 2.5 values averaged 88.4% ± 12.0 (±95% CI) of the Logan PM 2.5 values, indicating no significant differences between PM 2.5 as measured at the two sites. This is not unexpected as PM 2.5 is a subset of the PM 10 and the smaller PM 2.5 particles are much more likely to remain suspended in the atmosphe re. For example, in still air, the settling velocity of a 2.5 μm diameter particle is sixteen times slower than a 10 μm diameter particle (Cooper and Alley, 2002).10 410000 415000 420000 425000 430000 435000

UTM Easting (NAD27) 4605000 4610000 4615000 4620000 4625000 4630000 4635000 4640000 4645000UTM Northing (NAD27) Smithfield Newton Richmond Clarkston

Logan

Mendon

Wellsville Hyrum USU

Figure 6. Normalized PM 10 concentrations measured in northern Utah’s Cache Valley,

Oct. 2002 – Feb. 2003.

2003/2004 PM 2.5 Homogeneity (Saturation) Study

Co-location of the MiniVol samplers with the R&P (Logan site) FRM PM 2.5 sampler showed the portable samplers generally reported similar PM 2.5 concentrations. As can be seen in Figure 7, th e tested MiniVols’ measured PM 2.5 concentrations differed from those reported by the FRM sampler by ap proximately –21% to +47%. The overall average error was found to be a remarkable –0.9%. Given the magnitude and variability of these percentages and the re lative tightness of their indivi dual confidence intervals, the final data analysis calculations for the describe saturation study included the appropriate

individual instrumenta tion correction factors.11 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4

Am a l ga A SF Ballard Junc.

Cl

a rks

t on

C

o rnish

E

v ans Fa

rm

Fran kl

in Hunt er

Ed

Hyrum Mendon New ton

Pr

e st

on/ H.E.

R

i c hm

ond USU

W

el

l sv

i ll

eNormailzed Ratio (to Logan FRM)

Figure 7. Average percent error for the tested Mi niVol samplers when compared to a colocated FRM PM 2.5 sampler (error bars = 95% confidence interval).

A total of 22 sampling days were observed for the 2003/2004 winter sampling period. Out of a potential total sample number of 374 samples (22 sample days x 17 sample sites), 80 (21.4%) individual samples we re not obtained due to sampler failure or operator error. Typical expl anations included battery or pump failure, especially during extreme temperature events (< -10oC), or erro rs in setting of the on-board timer/alarm.

PM 2.5 concentrations observed during the study, as measured at the Logan city site, varied from 3 to 128 μg m -3

.

Similar to the 2002/2003 PM 10 homogeneity study, the Cache Valley appeared to be relatively homogeneous in terms PM 2.5 concentrations, although some day-to-day

variations were observed in the specific location of PM 2.5 maximums and minimums. Figure 8 shows the average site-to-site PM 2.5 concentrations on good-to-moderate days (<65 μg m -3 ) normalized to the Valley-wide PM 2.5 concentrations. In other words, on any given day, the PM 2.5 concentration at a ny particular site was divided by the overall Valley-wide PM 2.5 average concentration measured on that day. This approach was used to minimize potential biases when averaging all of the individual sites’ data (e.g. not allowing differences on “low” days to be ove rshadowed by variations on “high” days). This differs from the approach used for the 2002/2003 PM 10 saturation study, wherein the12 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8

Amalg a A SF

B

a l l a rd

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. Cla

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Eva

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H yru

m

Mendon Newton

P r e s to

n

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c h mo

nd USU We

l lsville

S mit

h f ie

ld Lo g anPM2.5Normalized to Average concentrations were normalized to the Logan site. The new approach allowed for

calculation of confidence inte rvals about the Logan site as well the other locations.

As can be seen, on the good-to-moderate days, some site-to-site variation did seem to exist; however, with inclusion of th e 95% confidence intervals (error bars), the data set shows statistically homogeneous c oncentrations. For example, confidence intervals for Hyrum and Mendon overl ap Evan’s Farm and Newton PM 2.5 confidence intervals, which, in turn, overlap the conf idence intervals of the remaining sites. However, the Smithfield and Hyrum error ba rs do not overlap, so their average PM 2.5 concentrations on these selected days are stat istically different from each other, but not

from the data set taken as a whole.

Figure 8 . Average PM 2.5 concentrations normalized to the Valley-wide average PM 2.5 concentrations on days with PM 2.5 <65 μg m -3 (error bars = 95% confidence interval).

Figure 9 shows the normalized concentrations on days with PM 2.5 concentrations <65 μg m -3 in relation to the sampling sites ge ophysical location. The contours were prepared via Golden Software’s Surfer mapping software using a Kriging curve-fitting algorithm. As can be seen, there appears to be an identifiable tr end of increasing in PM 2.5 concentrations down the center of the Cache Va lley, with the highest values recorded in the low population areas of Wellsville, Ballard Junction and Franklin (Idaho), as was also shown in Figure 8.13 410000 420000 430000 440000

UTM Easting (NAD27) 4600000 4610000 4620000 4630000 4640000 4650000 4660000 4670000UTM Northing (NAD27) Preston, ID

Cornish, UT

Franklin, ID

Richmond

Smithfield

USU Logan Newton

Mendon

Hyrum Wellsville

Figure 9. Normalized PM 2.5 concentrations measured in northern Utah’s Cache Valley on good-to-moderate days (<65 μg m -3 ).

On “unhealthy” PM 2.5 days (concentrations >65 μg m -3 ), the data were more varied (larger confidence intervals), bu t overall more consistent in statistical homogeneity. As can be seen in Figure 10, only the Amalga and ASF sites, located essentially in the middle of the Cache Valley, we re statistically different from the average on these high pollution days. Similarly, only the Hyrum and Preston (Idaho) sites, on the far south and north ends of the Valley, were statistically lower than the average. However, once again, taken in it s entirety, the data set shows complete statistical overlap

or PM 2.5 homogeneity. It should be noted neither the Ball ard Junction or Clarkston samplers successfully operated during any if the high concentration episodes. Also, during these same periods the Newton and H unter Ed instruments only collected one and two samples, respectively.14 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8

Amal g a A SF

B

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. Clarks t on

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H yr

um

Mendon Newto n

P

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to

n

R ic h mo

nd USU Wellsville

S mit

h fi e l d LoganPM2.5Normalized to Average

Figure 10. Average PM 2.5 concentrations normalized to the Valley-wide average PM 2.5 concentrations on days with PM 2.5 >65 μg m -3 (error bars = 95% confidence interval).

Similar to Figure 9, Figure 11 shows the normalized concentrations on days with

PM 2.5 concentrations >65 μg m -3 in relation to the sampling sites geophysical location. As can be seen, there appears to be a more centralized zone of elevated PM 2.5 concentrations, but that zone encompasses mu ch of the center of the Cache Valley and its main population centers. The lowest average concentrations are found in the southeast (Hyrum) and northwest and north (Cornish, UT and Preston, ID) corners of the Cache Valley.15 410000 420000 430000 440000

UTM Easting (NAD27) 4600000 4610000 4620000 4630000 4640000 4650000 4660000 4670000UTM Northing (NAD27)

Smithfield Preston, ID

Franklin, ID Cornish, UT

Richmond

Logan USU

Hyrum Wellsville Mendon

Newton
Amalga

Figure 11. Normalized PM 2.5 concentrations measured in northern Utah’s Cache Valley on “unhealthy” days (>65 μg m -3 ).

PM 10 AND PM 2.5 HOMOGENEITY CONCLUSIONS

From the 2002/2003 PM 10 saturation study, although some slight areal variations may exist, within in a 95% confidence interval, the wintertime PM 10 concentrations throughout northern Utah’s Cache valley appear to be homogeneous. At the Logan and Smithfield sampling locations, which showed a statistically significant difference in their

PM 10 concentrations, no significant diffe rences were observed in their PM 2.5 concentrations.

As with the previous winter’s PM 10 study, some site-to-site PM 2.5 variations were shown to exist; however, within in a 95% confidence interval, the wintertime PM 2.5 concentrations throughout north ern Utah’s Cache Valley appear to be homogeneous. On days with 24-hr PM 2.5 concentrations less th en the 24-hr NAAQS (65 μ g m -3 ), the highest

concentrations tended towards the center of the Valley, which generally tended to16 correspond to the lower elevations of the local topography. On “unheal thy” days or days

in which the PM 2.5 concentrations where greater th an the 24-hr NAAQS, the Valley was once again found to be statistically homogene ous. However, during these episodes, the

maximum concentration area was much broade r and located over most of the population zones on the Utah side of the Cache Valley.

The homogeneity of the PM 10 and PM 2.5 concentrations indicates that the particulate issue is not just a problem for the main population center, Logan, but for all of the communities of the Cache Valley. Therefor e, the solution to the problem will have to involve all of the surrounding communities17 

### CACHE VALLEY AMBIEN T AMMONIA STUDIES

Contributing Authors

Dr. Randal S. Martin Dongzi Zhu, M.S. Env. Eng. Candidate Kori D. Moore, M.S. Env. Eng. Candidate Dept. of Civil & Environmental Engineering Utah State University Logan, UT

R. Neal Olson Utah Air Monitoring Center West Valley City, UT18 INTRODUCTION

As was mentioned in the Overall Intr oduction, the nominal composition of the

PM 2.5 particles in the Cache Valley is domin ated by ammonium salts, with ammonium nitrate accounting for 50-95% of the total particulate mass. For comparison, PM 2.5 in

most rural areas in the western United States are typically dominated by total carbonaceous mass and crustal materials (EPA , 2003). Urban areas in the western US, are typically dominated by carbonaceous materia l; however, nitrate salt s appear to be a significant portion of the PM 2.5 in the southern California area (EPA, 2003). Both rural

and urban areas in the eastern US are domi nated by the sulfate salts, with a strong contribution from carbonaceous materials (EPA, 2003).

The dominance of secondary, ammonium-based particulate material in the Cache Valley suggested a likely abundance of ambient gas-phased ammonia (NH 3 ) in the local atmosphere. The strong dependency of the local economy on agri culture, especially livestock production, further supported this supposition. The most current Utah state economic report indicates that Cache Count, UT had total agricultural receipts in 2004 of $121.6 million, with 83.2% of that attributable to livestock production (UGOPB, 2006).

The most recent data available for Franklin County, ID (2000) show that agriculture accounted for total cash receipts of $66.0 million, with livestock production accounting for 85.6% of the county’s agricultural tota l (Sonoran Institute, 2006).

In order to investigate leve ls of ambient, gas-phase NH 3 and whether NH 3 is the limiting factor in NH 4 NO 3 formation, an ammonia sampling station was co-located at the Logan city sampling site to establish overall ambient levels of gas-phase and particulatephase NH 3 , as well as the levels of associated an ions and cations. Subsequent to this investigation, an additional a program was initiated in the Fall of2004 to monitor realtime ambient ammonia concentrations at th e downtown Logan, UT (urban) location, the site historically used for federal complianc e monitoring, and a rura l site, located away from significant, typical “city-related” polluta nt sources. To be representative of the area, a rural site was sought out, such that it was in the proximity of locally-typical expected rural ammonia sources, such as small cattle operations (“mom and pop” dairies), working agricultural fields, a nd natural and constructed wetlands. The secondary site chosen was near Amalga, UT. The goal of the second study was to see if the Logan location was repres entative of valley-wide NH 3 concentrations or if there were significant differences between urban and rural locations.

METHODOLOGY

Ambient Gas- and Particulate-Ph ase Ammonia and Related Ions

The ambient gas-phase ammonia and acid sa mpling system was co-located at the Logan city sampling site and sampled on an every sixth day schedule. A URG, Inc. Model 3000C Annular Denuder System (ADS) (URG, 2000) was used for collection of 24-hour averaged gas- and particulate-phase samples. The full system operates at 10 Lpm and consists of a sharp-cut PM 2.5 cyclone, followed one or two acid gas (Na 2 CO 3 -19 coated) denuders, followed by the NH 3 gas (citric acid-coated) denuder, followed by a 2- stage filter pack assembly. For the purpos e of this study, the samp ling was initiated in October of 2002 and continued through the end of 2003.

The NH 3 collection denuders were prepared prior to exposure by coating the inner surfaces with a 1% citric acid solution ( 1.0 g citric acid, 99 ml of methanol, 1 ml glycerol). For acid gas collection, 1% Na 2 CO 3 solutions were prepared from 1.0 g

Na 2 CO 3 , 1.0 g glycerol, 50 ml double-distille d, deionized water (DDW) and 50 ml methanol. Glycerol was used to make the denuder surface more adhesive and prevent

oxidation of nitrite to nitr ate by ozone. Within the ADS, air was drawn through the cyclone for large particle removal, then through the Na 2 CO 3 -coated denuder where acid gases were collected, and then through the citric acid-coated denuder where NH 3 (g) was

absorbed to the walls. The air stream was th en drawn through a filter pack to collect the particulate matter for mass and compositional determination, followed by the nylon backup filter. The system was enclosed in a weatherproof box, which was kept at a lower

limit of 7 0 C if the ambient temperature was less than 7 0 C, or 2 0 C above ambient temperature if the ambient temperature was greater than 7 0 C. The system was connected to a pump with an accompanying mass flow controller and a dry gas meter. The mass flow controller allowed precise control of airflow through the a nnular denuder/cyclone assembly. The Gallus 2000 dry gas meter (S chlumberger, Reims Cedex, France) was also plumbed to the system and was calibra ted before use to insure precise sample volumetric reading.

After exposure, the denuder tubes were separately eluted with 10 ml (NH 3 ) and 30 ml (acid gases) of double-disti lled, deionized water. Addition ally, 10 μL of concentrated

H 2 SO 4 was added to the NH 3 extract to acidify the sample, ensuring the collected gasphase ammonia (NH 3 ) would remain in solution as the more soluble ionic species, ammonium (NH 4 + ). The samples were stored in the dark at 4oC until the extract concentrations were quantifie d via ion chromatography. The Dionex IC system consisted of the following equipment: AS 40 Automate d Sampler, CD 20 Conductivity Detector, GP 40 Gradient Pump, Membrane Suppresso r, LC 25 Chromatography Oven, and an

IonPac ® AS4A-SC (4 mm) anion column or an IonPac ® CS12A cation column, AG4ASC anion guard column or CG12A cati on guard column, depending on the ionic species of interest.

For anion analysis from the denuder washes, a 25- μ L injection loop was used in the IC, while for cations analysis from the denuder washes, an 80- μ L injection loop was used; and for filter extraction cations, a 195- μ L loop was used. This was because the

concentration of filtered extraction cations was much lower than that from denuder washes, and a larger loop allo wed injection of more sample onto IC which allowed more consistent peak detection. For anions analysis, DDW filtered through a 0.2 μ m filter was used as reagent water and 1.7 nM sodium bicarbonate and 1.8 nM sodium carbonate

solution as the eluant. Stock sta ndard solutions of 1000 mg/L of C1 - , NO 3 - , NO 2 - , SO 4 2-
were prepared from ACS reagent grade salt s (Fisher, Fair Lawn, NJ). For cations analysis, 0.15 M H 2 SO 4 was used as the eluant. Stoc k standard solutions of 1000 mg/L

of Na + , K + , Mg +2 , Ca +2 , NH 4 + were prepared from ACS regent grade materials.20 Calibration curves were prepared using 1, 5, 10 mg/L (ppm) stock standard solutions and were verified on each working day and after approximately 20 samples. Blank and continuing calibration verification standards ( CCV), such as 5 ppm standard anions or cations solutions, were tested approximately every 10 samples. P eak identification and data processing were performed using Dione x PeakNet Data Chromatography software (Version 2.0). Ambient air co ncentrations were calculated from the IC analytic results and sampled air volume.

Urban vs. Rural Ambient Gas-Phase Ammonia Study

This study began in November 2004 and went through April 2005, gapping the typical Cache Valley PM 2.5 “season”. It should be men tioned that due to equipment problems the Logan city NH 3 system, sampling did not actu ally begin until Dec. 7, 2004. ThermoEnvironmental Instruments Model 17C Chemiluminescent Ammonia Analyzers were installed in climate controlled samp ling trailers at the Logan site (41.7309°N, 111.8376°W, ele. 1380 m asl) and at a newly established site near Amalga, UT, approximately 15.1 km northwest of the Logan site, roughly near the center of the Utah portion of the Cache Valley. Within 3 km of the rural site are a number of agricultural fields, two small dairy operations (50-100 cows each), natural wetlands and an associated stream system, a waste lagoon, and a small cheese factory. The rural site specific coordinates are as follows: 41.8584°N, 111.8943°W, ele. 1355 m asl. All UTMs given

are in NAD27 coordinates.

At both locations, sample air was transf erred into the analyzers through glass sampling manifolds and Teflon ® tubing. The Model 17C Analyzers operate through the sequential measurement of NO, NO 2 , and NH 3 via ozone initiated chemiluminescence and surfaced catalyzed oxidation of the ammoni a. The system first measures ambient NO

and NO 2 as describe by typical federal refere nce method gas-phase chemiluminescence (40CFR50, App. F, 2006), as such the NO

x data are archived and available as well as the

ammonia. The NH 3 analyzer adds an additional 7 75°C stainless stee l converter to

oxidize the NH 3 to NO. The 17C then measures the additional system response due to the newly created NO, which is then re ported as ambient ammonia (TECO, 2004).

The instruments were calibrated or zero/s pan checked on an at least semi-weekly basis using commercially-purch ased ammonia and zero gas standards. The instrument has a reported lower detectable limit of 1 ppb, a response time of 120 seconds, and a linearity of ±1% at rang es up to 20,000 ppb (TECO, 2004). Similar instrument characteristics were also reported via a sepa rate independent study (C owen et al., 2004). Additional operational details can be found at the manufacture’s website (TECO, 2006).

RESULTS AND DISCUSSION

Ambient Gas- and Particulate-Ph ase Ammonia and Related Ions21 0 5 10 15 20 25

10/17/2002 12/16/2002 2/14/2003 4/15/2003 6/14/2003 8/13/2003 10/12/2003 12/11/2003Gas-Phase NH3(ppb)

0 5 10 15 20 25 30 35 40 45 50Logan PM2.5(μg m-3)

Gas NH3 conc. Logan PM2.5 Figure 12 shows the ambient, gas-phase am monia concentrations measured at the Logan site from October 2002 through December 2003. The average overall concentration is 9.3 ppb ± 1.2 (95% CI). The minimum NH 3 concentrations were around 2.5 ppb, which were observed in the summer time, and the maximum concentrations approached 25 ppb, which were observed in the wi ntertime. This is well above what is typically considered tropos pheric background levels (0.05 – 0.2 ppb) and compares to other areas of high agricultura l activity (Robarge et al., 2000; Finlayson- Pitts and Pitts, 2000). The elevated ammonia levels are not une xpected due to the enclosed nature of the Valley’s airshed, especially during winter time inversion episodes, and the common nature of livestock produc tion in the local region.

Figure 12. Ambient NH 3 and PM 2.5 measured in Logan, Utah.

Based primarily on the number of livesto ck in the Cache Valley, the Utah DAQ estimates daily (wintertime) emissions on th e order of 4.8 metric tons (UDAQ, 2006). It is well recognized that current NH 3 emissions algorithms are considered highly uncertain (CAEAAFO, 2002; CENR, 2001; FAO, 2001); howev er, examination of these first order emissions estimates can give some insight in to local atmospheric photochemical particle formation. The Utah DAQ has also estimated daily NO

x and SO

x emissions at 8.3 and 8.5 metric tons. Based on these numbers, th ere is easily enough av ailable gas-phase NH 3 to neutralize the emitted SO

x . However, the NO

x -NH 3 particle conversion is more accurately represented as an equilibrium reaction, and as such, complete conversion would not be expected. Furthermore, the re sultant ammonium nitrate particle formation22 0 2 4 6 8 10 12

Dec/02, Jan,

Feb/03 Mar, Apr, May Jun, Jul, Aug Sep, Oct, Nov Dec/03, Jan,

Feb/04Gas-Phase NH3(g/m3) is favored during cold and humid (i.e. foggy) conditions as experienced during the Cache Valley’s winter months. The high ambient NH 3 concentrations suggest the NH 3 is in

excess and the emission estimates of all of the noted species may need to be revised.

The concurrent PM 2.5 concentrations from the Logan site are also shown in Figure 7 and it appears that the two parameters may be correlated. Linear regression analysis shows only a moderate correlation (r 2 = 0.537); however, it can be said that the higher

PM 2.5 concentrations typically occurred during periods of elevated ambient ammonia. Further, the regression analysis proportionality constant, the “slope” term, is very nearly equal to unity (1.006), suggesting that in the local area, a 1 pp b increase or decrease in

ambient NH 3 would be paralleled by a similar change in the PM 2.5 concentration. This is not to suggest that NH 3 emissions, and thereby particulat e ammonium nitrate, increase in the winter months. More likely these increa ses are related to seasonal decreases in the atmospheric mixing volume and dilution rates.

On a seasonal basis, the winter months (Dec., Jan., Feb.) showed the highest NH 3 concentrations, averaging 13.9 ppb ± 2.99 (95% CI), which was statistically different from the remaining three seasons (see Figure 13 ). The spring (Mar., Apr, May), summer (Jun., Jul., Aug.) and fall (Sept., Oct., Nov.) NH 3 concentrations were not significantly different from each other. The overall average ambient NH 3 concentration for these three seasons was 7.7 ppb ± 0.94.

Figure 13. Seasonal variations of Cache Valley ga s-phase ammonia (error bars represent 95% confidence intervals).23 

### -- based on all three algorithms (treated equally)

0 10 20 30 40 50 60 70 80 90 100

Winter Spring Summer FallPercent of Samples

%HNO3 Limited %Transitional %NH3 Limited In order to more fully examine whether the gas-phase NH 3 is in abundance or deficit in relation to potential formation of particulate ammoni um nitrate, three separate algorithms were applied to the collected ionic concentration da ta. The models used were

the excess NH3 model of Blanchard et al. (2000), the partic ulate-to-total NO 3 - ratio model also by Blanchard et al. ( 2000), and Gas Ratio Analysis (free NH 3 to total HNO 3 ) model of Ansari and Pandis (1999). The de tails of these models, and their accuracy compared to more detailed atmospheric photochemical models, are given in the associated references, but in brief they all at tempt to model the gas- and particulate phase ion balance. The average results of these three individual calculati ons can be seen in Figure 14.

Figure 14 . Seasonal determination of HNO3- or NH3-limited particulate ammonium

nitrate formation.

As can be seen, during the cri tical wintertime periods, the NH 4 NO 3 formation was limited by the availability of ambient nitric acid (HNO 3 ) for approximately 90% of the observed samples. Although not relevant to the Cache Valley’s elevated wintertime

PM 2.5 concentrations, the two of the th ree remaining seasons also should NH 3 -rich (HNO 3 -limited) atmospheres. Examination of the specific ionic concentrations and the particulate ammonium salts further s uggest that the wintertime gas-phase NH 3 is in excess by as much as a factor of two (2x) . More complete discussion of the above analysis can be found in Zhu (2005), and is pr esently in preparation for publication in a peer-reviewed journal.24 0 20 40 60 80 100 120 140 160 180 200

11/11/04 11/25/04 12/9/04 12/23/04 1/6/05 1/20/05 2/3/05 2/17/05 3/3/05 3/17/05 3/31/05 4/14/05 4/28/05

DateMixing Ratios (ppb) & Logan PM2.5(μg/m3)

Logan PM2.5 Amalga NH3 Logan NH3 Urban vs. Rural Ambient Gas-Phase Ammonia Study

As shown in Figure 15, the ambient NH 3 , as measured at both the Logan (urban) and Amalga (rural) sites followed similar tren ds and paralleled elevated and depressed periods with the measured PM 2.5 concentrations. The Logan ammonia concentrations showed a moderate linear regression correlation with the collocated PM 2.5 concentrations

with an R 2 value of 0.6543. The rural (Amalga) wa s statistically less well correlated showing an R 2 value of 0.4895. However, directly comparing the ambient ammonia

concentrations between the two sites show ed a correlation coefficient of 0.8255, with a proportionality constant of 2.5 and an inter cept of 7.6 ppb (using the Logan concentration as the independent variable), indicating the rural ammonia concentrations were approximately 21⁄2 times the average urban values.

Figure 15 . Logan and Amalga ambient NH 3 (24-hr avg) compared to Logan PM 2.5 (24- hr avg).

As can also be derived from Figure 15, th e Logan site recorded a maximum 24-hr average value 74 ppb and a minimum value of <1 ppb, with a period daily average value of 19 ppb. This average value is remarkably consistent with that reported by Martin and

Zhu (2004), 14 ppb, for the Logan location over the previous two winters using the previously described separate, denuder tube technique. The Amalga location showed much higher concentrations, with maximum, minimum, and average values of 200 ppb, 1 ppb, and 58 ppb, respectively. It is of interest to note that at the Amalga location, 1-hr average values >200 ppb were not unusual, particularly during strong inversion events

and the maximum 1-hr NH 3 concentration observed was 373 ppb.25 0 10 20 30 40 50 60 70 80 90 100

Nov 04 Dec 04 Jan 05 Feb 05 Mar 05 Apr 05Ammonia Concentration (ppb)

Amalga NH3 Logan NH3

At the 95% confidence interval, the mont hly ambient ammonia averages at the rural (Amalga) site were statistically higher than the concentrations observed at the urban (Logan) location (see Figure 16). This differenc e is believed to be due to the relative

abundance of NH 3 sources near the rural location, and the increased likelihood of local photochemistry due to the increased presence of possible reactants at the urban site (NOx, VOC, etc.) due to increased nearby pollutant sources (especially automobile traffic). As with Figure 15, Figure 16 al so shows the highest NH 3 concentrations occurred in January and February, when persistent i nversions where present and high PM 2.5 concentrations

were observed.

Figure 16 . Monthly ambient ammonia averages for Logan (urban) and Amalga (rural),

UT.

As can be seen in Figures 17 and 18, both the Logan and Amlaga NH 3 displayed noticeable diurnal patterns, with maximums typically occurring the morning hours (6 am to 10 am MST) and the minimum usually in th e mid-afternoon to early evening (2 pm to 6 pm MST). The hour-to-hour diurnal differenc e appeared stronger, particularly at the rural location, when the ambient concentrations were at their highe st in February and

March.26 

## Average Amalga Diurnal NH 3

0 20 40 60 80 100 120 140

0 2 4 6 8 10 12 14 16 18 20 22 24

Time of Day (MST)NH3(ppb)

Nov-04 Dec-04 Jan-05 Feb-05 Mar-05 "Apr-05" Figure 17. Logan (urban) diurnal ambient ammonia behavior.

Figure 18. Amalga (rural) diurnal ambient ammonia behavior. 

## Average Logan Diurnal NH 3

0 5 10 15 20 25 30 35 40

0 2 4 6 8 10 12 14 16 18 20 22 24

Time of Day (MST)NH3(ppb)

Dec-04 Jan-05 Feb-05 Mar-05 Apr-0527 

### Wind Direction in Degrees vs Avg NH 3

0 20 40 60 80 100 120 0

45

90

135

180 225 270 315

Nov-04 Dec-04 Jan-05 Feb-04 Mar-05 Apr-05 The abundance of ambient NH 3 at the rural location suggested that the site may be significantly impacted by an adjacent amm onia source. However, examination of

observed NH 3 concentrations as a function of wi nd direction showed that the ammonia sources in the rural location seemed ubiquit ous and the concentrati ons were consistent from most wind directions (s ee Figure 19). Furthermore, the data, averaged for wind direction, show complete sta tistical overlap (at the 95% c onfidence interval) within any given month. It should be mentioned; how ever, that during February and March, the average observed concentrations from th e east and southeast, respectively, were statistically higher than some , but not all, of the other wind directions. While the previously mentioned cheese factory is approx imately 1.4 km to the south-southeast, the land to east is mostly pasture land, agricultura l fields, and natural we tlands/river areas. The dominant wind directions during the study period were north or northeast and south, southwest, or west, roughly following the topographical confines of the valley.

Figure 19. Amalga (rural) NH 3 concentrations as a function of wind direction.28 AMBIENT AMMONIA CONCLUSIONS

Concentrations of ambient gas-phase a mmonia reached values as high as 25 ppb during winter inversions, but averaged closer to 14 ppb. The gas-phase NH 3 concentrations in the two observed wi nter periods (2002/2003 and 2003/2004) were almost same, suggesting consistent polluta nt wintertime emission rates and similar inversion-dominated pollutant trap ping. Spring, summer, and fall NH 3 concentrations were significantly lower, averaging just over one half of the wintertime levels. The data showed only a moderate relationship between ambient NH 3 and PM 2.5 (R 2 = 0.537), but the overall trend suggested a one-to-one rate of change between the two parameters.

Applying an excess ammonia mode l, a particulate-to total-NO 3 - model and gasratio model, showed that all the of resu lts indicated the Cache Valley’s wintertime atmosphere was ammonia-rich or HNO 3 -limited in reference of secondary NH 4 NO 3 aerosol formation (using the Logan site as the refence location). Since Cache Valley’s atmosphere has been proved to be ammonia rich, or HNO 3 -limited through the herein described study, reduction on HNO 3 will produces a greater, more immediate, reduction

of aerosol NH 4 NO 3 than will an equivalent reduction of NH 3 . Programs to be implemented could include vehicle insp ection and maintenance (I&M) programs, increased public transit programs, car poo ling, and other programs to reduce vehicle

miles traveled.

The monthly average ambient ammonia con centrations at the urban varied from 5-31 ppb, with the highest values occurring in February and March, the same time periods when maximum PM 2.5 concentrations were observed. The highest daily average observed was 74 ppb and the test period (five month) average was 19 ppb. These values compare well to previous investigators reported values for the Logan area (Martin and Zhu, 2004; Mangelson et al., 1997) and are genera lly much higher than those reported for other urban areas, with the exception on Phoenix, AZ (Watson et al., 1994) and Riverside, CA (Yoong, 1981). The listed two urban areas reported ambient NH 3 concentrations on the same order as the Logan site.

The nearby rural (Amalga) site showed monthly average ammonia concentrations of 20 to 87 ppb, with the highest values occurr ing during the same months as those at the urban site. The overall correlation (R 2 ) between the two sites was 0.8255, with a derived relationship between locations as shown in Equation 1:

[NH 3 ] Rural = 2.51 * [NH 3 ] Urban + 7.58 (Equation 1)

where all concentrations ar e in parts per billion (ppb).

The highest daily average observed at the rural was 200 ppb and the test period (six month) average was 58 ppb. The maximum 1-hr NH 3 concentration observed for the rural location was 373 ppb. These values are well above those reported for nonagricultural, rural areas (Wat son et al. 1994; Pryor et al. 2001; Thoni et al. 2003), but are29 in line with rural si tes collocated around strong agricultu ral production facilities (Mopunt et al., 2002; McCullo ch et al., 1998).

Comparison of hourly ambient NH 3 concentrations with hourly averaged wind

directions showed near co mplete statistical homogeneit y, although there were a few direction-to-direction differences during th e months of February and March. The independent nature of the ammonia concen trations in relation to the wind vectors suggests that the rural NH 3 sources are well-dispersed th roughout the Cache Valley and it is likely the no single source (no one point, area, etc. s ource) dominates the local NH 3 emissions budget. It would seem more likely the high rural ammoni a concentrations are due to a multitude of valley-wide sources.

Additionally, as shown in Equation 1, the rural ammonia levels are on the average 2.5x greater than the urban levels. As also mentioned above, as measured at the Logan site alone, was in ammonia ex cess by a factor of approximate ly two in regard to the photochemical formation of particulate ammonium nitrate. If indeed the Amalga location is representative of the other rural areas of the Cache Valley, the local atmosphere may be more ammonia-rich than previ ously assumed. This would, in turn, mean that the worth of potential NH 3 reduction scenarios would have to be very carefully examined.30 

### ON-ROAD VEHICLE EMISSIONS IN CACHE VALLEY (2004)

Contributing Authors

Dr. Randal S. Martin Mark Greenwood, B.S. Env. Eng. student Lisa Kent, B.S. Env. Eng. student Kori D. Moore, B.S. Env. Eng. student

Clint Rogers, B.S. Env. Eng. student Angela Squires, B.S. Env. Eng. student Lisa Kent, B.S. Env. Eng. student Dept. of Civil & Environmental Engineering Utah State University Logan, UT31 INTRODUCTION

Research described within the ammonia se ction of this document showed that the local Cache Valley ambient air is ammonia-ri ch during the winter months, meaning that the limiting compound is the nitric acid (HNO 3 ) that combines with the gaseous ammonia (NH 3 ) to form NH 4 NO 3 . Nitric acid is photchemically formed in the atmosphere from precursor oxides of nitrogen (NO

x ) compounds through a series of photochemical reactions involving other re actants such as ozone (O 3 ), hydroxyl radicals (OH), reactive volatile organic compounds (VOCs), and availabl e solar radiation (insolation). The main

source of NO

x and VOCs in Cache Valley is the tr ansportation sector with over 80,000 vehicles registered in Cache County, UT a nd Franklin County, ID. The Cache County Assessor lists approximately 67,000 motor vehicles , half of which are 1995 or older, as being registered within the county (Cache County, 2004). Franklin County, ID, as of 2004, had 12,900 total registered motor vehicles of similar age structure (IDT, 2006).

A potentially effective way to control NO

x and VOC emissions is to control the emissions from automobiles, and this is typically accomplished through the implementation of an Inspection and Maintena nce (I & M) Program that tests emissions

on an annual or bi-annual basis. Vehicles th at do not pass the test must be fixed before being allowed to register. This option for controlling pollutant emissions is currently being considered by Cache County, but info rmation was lacking on what expected

emissions of the current vehicle fleet and what fraction of the fleet may be expected to fail or pass an I & M Program. As such, a series of on-road emission tests were performed in May 2004 in and around Logan, UT.

METHODOLOGY

The vehicle emission testing was done using an MD-LaserTech RSD (remote sensing device) borrowed from Utah County. Additionally, a trained operator, Todd Rittle, from the Utah County Department of Health was on hand to operate and calibrate all of the test equipment. In brief, the sy stem shot infrared and ultraviolet laser beams across a roadway, reflected of a polished mirro r and returned to the transceiver, where wavelength-specific energy absorption was reco rded. The concentra tions of NOx, VOCs, CO, and CO 2 within the vehicle plume were the in strumental correlated with the laser

attenuation. Additional information record ed included vehicle speed, acceleration, and license plate data (the latter recorded via a time-marked photograph. It should also be noted that a beam height of approximately 14” was selected, knowing this be height was a choice between measurement of typical car or typical pickup exhaust heights. The 14” was more typical of the passenger automobile.

The testing occurred at various roadside sites along high tr affic areas throughout Cache Valley during the period of May 13- 20, 2004. A relative map of the tested locations can be seen in Figure 20. Finall y, the slope of the road at each site was subsequently measured by USU undergraduate Environm ental Engineering students using standard surveying techniques and used to calculate a comparison parameter known as vehicle specific power (VSP).32 Figure 20. Locations of May 2004 Cache Valley on-road vehicle emissions study.

RESULTS AND DISCUSSION

The number of (valid) vehicles surveyed fo r exhaust emissions at all sites within Cache Valley was 12,464 at an average speed of 34.4 mph. The vehicles were separated into bins by vehicle year beginning with the year 1980 and conti nuing at five year

increments until the last bin of 1996 and older. Figure 21 displays how the sample set of surveyed vehicles sorted by vehicle year co mpares with the total number of registered vehicles in the county also sorted by vehicle y ear. The two curves in this figure are very similar suggesting that the sampled data is a good descriptor of the general vehicle population.

Figure 22 shows the percenta ge of the total bin popul ation represented in the sampling set. The majority of registered ca rs in Cache County have a vehicle year of 1990 or greater, and this divi sion can be seen in Figure 22 as the 1990-95 and older than 1996 bins had the greatest percen tage of total cars sampled.33 Total and Sampled Vehicles

0 5000 10000 15000 20000 25000 30000 35000 40000

< 1980 1980-1984 1985-1989 1990-1995 ≥ 1996

Model YearNumber of Vehicles

0 500 1000 1500 2000 2500 3000 3500 4000 Total Vehicle Fleet Sampled Vehicles

% Sampled in each age group

0.0% 2.0% 4.0% 6.0% 8.0% 10.0% 12.0%

< 1980 1980-1984 1985-1989 1990-1995 ≥ 1996 Figure 21. Vehicles surveyed with compared to total Cache County registered vehicles.

Figure 22. Surveyed vehicles grouped by vehicle year.

The data of exhaust emissions obtained from the surveyed cars were analyzed to see the percentage of cars in each vehicle year classi fication that would exceed the emission limits for carbon monoxide (CO), hydr ocarbons (VOCs), and oxides of nitrogen (NO

x ). Carbon dioxide (CO 2 ) was also monitored, but it is not reported here as it is not a presently regulated automobile emission po llutant. Each pollutant was evaluated34 <

1980 1980-

1984 1985-

1989 1990-

1995 ≥

1996 Fail 0.0% 5.0% 10.0% 15.0%

Percent of

Vehicles

Vehicle Year Percent of Failing Vehicles for Vehicle Year for

NOx individually, which means that a single vehicle could poten tially fail emissions testing based on one, two, or all three emission limits.

Figure 23 shows the percentage of vehicles by vehicle year th at would fail an oxides of nitrogen emissions test, based on a concentration limit 1776 ppm. As seen in the figure, all of the age classes are below a 15% failure rate. This means that a low number of cars are failing for NO

x , which is the pollutant of concern for PM 2.5 formation. The percentage of vehicles th at failed on the basis of NO

x is small compared to the results for CO and HC. Overall, 4.5% of the meas ured vehicles would presumably fail an inspection test, accounting for 25.4% of the total automobile NO

x emissions. The average tailpipe NO

x concentration measured was 396 ± 11 ppm.

Figure 23. Percent of vehicles by vehicle year exceeding NO

x emission limits.

The older cars and newer cars result in a smaller percentage of failures than vehicles with a vehicle year of 1980 to 1989. It can be seen from Figure 24 that once again the average NO

x concentration for failing vehicles is not heavily dependent on vehicle year.35 0 500 1000 1500 2000 2500 3000

ppm

< 1980 1980-

1984 1985-

1989 1990-

1995 ≥ 1996

Vehicle Year Average NOx for Sampled Vehicles

Passing Vehicle Emissions Failing Vehicle Emissions

< 1980 1980-

1984 1985-

1989 1990-

1995 ≥ 1996 Fail 0.0% 10.0% 20.0% 30.0% 40.0% 50.0% 60.0% 70.0% 80.0%

Percent of

Vehicles

Vehicle Year Percent of Failing Vehicles for Vehicle Year for HC Figure 24

. Average passing vehicle emissions versus average non-passing vehicle emissions

for NO

x .

The data trends for hydrocarbons (VOCs) as shown in Figure 25 are similar to

those of NO

x . Older vehicle year bins have a high percentage of emission failures, while newer vehicles have a smaller percentage of failures. The percent of failing vehicles for hydrocarbons is based on a failing limit of 225 ppm. The average tailpipe VOC concentration measured was 99.6 ± 14.2 ppm. Overall, 10.3% of the measured vehicles would presumably fail an inspection test, accounting for 47.8% of the total automobile

NO

x emissions.

Figure 25

. Percent of vehicles by vehicle y ear exceeding VOC (HC) emission limits.36 0 100 200 300 400 500 600 700 800

ppm

< 1980 1980-

1984 1985-

1989 1990-

1995 ≥ 1996

Vehicle Year Average Hydrocarbons for Sampled Vehicles

Passing Vehicle Emissions Failing Vehicle Emissions From Figure 26, it can be seen that the failing vehicles emit on average 6 times more hydrocarbons than those that pass. Once again, the vehicle year does not have a big impact on the hydrocarbon concentrati on being emitted by the failing vehicles.

Figure 26. Average passing vehicle emissions versus average non-passing vehicle emissions for VOC (HC).

Although, not relevant to Cache Valley’s PM 2.5 problem, nor a CO problem, it is interesting to examine the vehicle fleets CO emissions with respect to the number of “high” emitters. Overall, the average CO concentration was 0.61 ± 0.05% (at the 95% confidence interval). Figure 27 shows the pe rcentage of vehicles sampled per vehicle year classification that woul d fail emissions test based on carbon monoxide with a limit of 1.14% CO. In total, 11.4% of the observed vehicle fleet would fail such an emissions test and these vehicles were responsible for 45.9% of the total measured CO. From Figure 27 it can also be seen th at the highest percent of vehi cles that would fail according to year are those that are olde r than 1985. It also shows that less than 10% of the vehicles

that are newer than 1995 would fail an emissions test for CO.37 < 1980 1980-

1984 1985-

1989 1990-

1995 ≥ 1996 Fail 0.0% 10.0% 20.0% 30.0% 40.0% 50.0% 60.0% 70.0%

Percent of

Vehicles

Vehicle Year Percent of Failing Vehicles for Vehicle Year for CO

0 0.5

1 1.5

2 2.5

3 3.5

4

% CO

< 1980 1980-

1984 1985-

1989 1990-

1995 ≥ 1996

Vehicle Year Average CO for Sampled Vehicles

Passing Vehicle Emissions Failing Vehicle Emissions Figure 27. Percent of vehicles by vehicle year exceeding CO emission limits.

From Figure 28, it can be seen that the failing vehicles appear to emit on average of five to seven times more CO by percentage of total exhaust than the passing vehicles. It is important to note that the average CO concentration for the failing vehicles does not vary greatly with vehicle year. The 1996 and newer cars that would fail an emissions test are also significant emitters like the older cars.

Figure 28

. Average passing vehicle emissions versus average non-passing vehicle emissions for CO.38 0 500 1000 1500 2000 2500 3000 3500 4000

Number of

Vehicles

< 1980 1980-1984 1985-1989 1990-1995 ≥ 1996

Model Year Projected Number of Failing Vehicles per pollutant

CO

HC

NOx The percent of vehicles that would fa il per age class for each pollutant was projected onto the Cache Valley fleet number s and is shown in Figure 29. The greatest number of cars projected to fail emissions testing would do so because of CO emission violations, except in the vehi cle year bin of 1980 and older, where more cars would fail due to VOC (HC) emission violations. The greatest number of potentially failed

emissions tests would come from the vehicle bins 1985 through 1989 and 1990-1995. The percentages and totals of failing cars can not be summed because some of the

vehicles would be counted more than once due to failing two or more emission tests.

Figure 29. Projection of Cache County vehicles expected to fail emissions test based on CO, VOC (HC), and NO

x emission limits.

It is of interest to compare the aver age emission concentrations of the target pollutants from Cache Valley to a similar study conducted in Utah County during 2003.

These results are shown in Fi gure 30. As can be seen, th e average automobile emission

concentrations for NO

x , VOCs (HC), and CO were all lo wer for the Cache County data set, even though an automobile I & M program is currently in place Utah County, but not Cache County. It should be noted from fi gure 30; however, that only the NOx emission concentrations showed a statistically significan t difference (at the 95% confidence level). At this point, no explanation can be given for this apparent discrepancy. However, possible explanations could in clude differences in vehicle fleet structure, the possible inclusion of larger engine (pickup, SUV) vehi cles in the Utah County study, or perhaps different test conditions (season, relative si te locations, vehicle operating conditions).39 0 100 200 300 400 500 600

NOx (ppm)PPM Cache Utah

0 20 40 60 80 100 120

HC (ppm)PPM Cache Utah

0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70

CO (%)% Cache Utah

Figure 30 . Average on-road vehicle emission concentration for Cache and Utah

Counties.

The data that was obtained for the Cache Valley has been compared to similar data collected in Virginia in 2003. In order to compare the Cache Valley data to Virginia the vehicle specific power was calculated for each vehicle that was sampled. The pollutant concentration was then compared to the vehicle specific power to allow a common term in comparing pollutant concentr ations. Virginia has an existing vehicle inspection and maintenan ce program, so by comparing the average pollutant concentrations per vehicle specific powe r one can obtain an approximation of the reductions in emitted pollutant concentrations from the vehicles.

Other researchers have suggested that a parameter referred to as vehicle specific power (VSP) may be a relevant way to rela te vehicle emissions to engine operating

conditions. VSP is defined as the vehicle’s estimated engi ne power divided by the mass of the vehicle and is typically given in units of kilowatts per metric ton (kW/t). In practice, VSP can be found as using empiri cal relationship given by Klausmeier and

McClintock (2003) as:

VSP = 4.364*sin(Grade in deg/57.3)*Sp eed + 0.22*Speed*Acceleration + 0.0657*Speed + 0.000027*Speed 3

Klausmeier and McClintock (2003) re ported for a Virginia study that NO

x emissions increase with VSP until a maximum occurred somewhere between 15 and 30 kW/t, depending on the age of the vehicles, with the older age vehicles reaching higher

maximum NO

x emissions at lower VSP values. The Virginia hydrocarbon (VOCs)

emission did not show as dramatic of vari ances with VSP; however, some decreasing40 VOC emissions with increasing VSP were obser ved particularly for older (pre 1985) age

class vehicles

Figure 31 shows the oxides of nitrogen emi ssions concentrations as compared to vehicle specific power for the different age classes observed in the Cache Valley study. The Cache Valley NO

x concentrations are generally greater ( ≈ 2x) for the given range of VSP than the Virginia data reported by Kl ausmeier and McClintock (2003), where a vehicle I & M program is in place. This may indicate that a vehicle I & M program

would be beneficial in reducing the amount of NO

x emitted into the Cache Valley atmosphere by vehicles, but may also be cause d by differences in vehicle fleet (although comparison to VSP and vehicle age should normalize that out.

NOx vs VSP

0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400

-100 -80 -60 -40 -20 0 20 40 60 80 100

VSP kW/tNOx ppm < 1980

1980-1984

1985-1989

1990-1995

≥ 1996

Figure 31. Cache Valley vehicle speci fic power compared to NO

x emission

concentrations.

Figure 32 shows the hydrocarbon (VOC) emissi on concentrations as compared to vehicle specific power for the different ve hicle age classes measured during the Cache Valley study. Comparing the data in Figure 32 to the previously mentioned Virginia data, it can be shown that the Cache Valley VOC concentrations are generally comparable to the Virginia hydrocarbon concentr ations and both data sets show relatively

little variation of VOC concen trations with VSP. This suggests that VOCs are not a strong function of the engines’ workload, but rather a function of the engines’ operating functions. an I/M program would not be very beneficial in hydrocarbon reduction.41 

### HC vs VSP

0 100 200 300 400 500 600 700 800 900

-100 -80 -60 -40 -20 0 20 40 60 80 100

VSP kW/tHC ppm < 1980

1980-1984

1985-1989

1990-1995

≥ 1996

Figure 32. Cache Valley vehicle specific pow er compared to VOC emission

concentrations.

ON-ROAD VEHICLE EMISSI ONS STUDY CONCLUSIONS

From the information on registered vehi cles that was obtained from the Utah Department of Motor Vehicles, the percenta ge of vehicles that are 1996 or newer was determined to be 49.4%. This means that appr oximately half of the registered cars in Cache Valley would be eligible for I & M testing with the OBD method.

The results of this study have also found th at the majority of vehicles that would fail a vehicle inspection and ma intenance test would do so for hydrocarbons (VOCs) and carbon monoxide (CO), although th e latter is not presently of concern in the Cache Valley, and that the majority of the vehicles that would fail would be older than 1996. The study indicated that approximately 4.5% and 10.3% of the Valley’s vehicles would fail inspections tests for NOx and VOCs, re spectively, and that these vehicles were responsible for 25.4% and 47.8% of the vall ey-wide emissions. The study has also shown that the average pollutant concentrati on for failing vehicles does not vary greatly with vehicle year. The 1996 and newer vehicl es that would fail an emissions test are significant pollutant contributors ju st like their older counterparts.

The comparison of the Cache Valley data to a similar study conducted in Virginia in an area with an I & M program suggests that the NO

x emission concentrations may be lowered with a local inspection program (based on the relationships between NO

x emissions and engine workload). A sim ilar comparison with VOCs suggest an I & M program may not improve VOC emission rates.42 

### CACHE VALLEY AIR QU ALITY PHONE SURVEY

Contributing Authors

Dr. Randal S. Martin Mark Greenwood, B.S. Env. Eng. student Lisa Kent, B.S. Env. Eng. student Kori D. Moore, B.S. Env. Eng. student

Clint Rogers, B.S. Env. Eng. student Angela Squires, B.S. Env. Eng. student Lisa Kent, B.S. Env. Eng. student Dept. of Civil & Environmental Engineering Utah State University Logan, UT43 INTRODUCTION

A random public phone survey was conducted in order to understand the feelings of the general public concerning the air quality and potential remediation scenarios within Cache Valley. The survey was conducte d in the Fall of 2004 by undergraduate Environmental Engineering students. Th e students randomly selected names and numbers from the the Cache County phone direct ory and called the re sidents until a total of 100 hundred response were obtained. As a separate, comparative exercise, a similar survey was given to the students Fall 2004 class of USU’s CEE 3610 (Environmental Management).

THE PHONE SURVEY

The citizen phone survey began with expl anation of what the survey was for and queried the respondent as to if they would like to participate. If they agreed they were asked the following ten questions:

1) How severe is Cache Valley’s air pollu tion problem (not a problem, small problem, medium problem, large problem, severe problem)?

2) Would you support a vehicle emissi on and inspection program (yes or no)?

3) How much would you be willing to pa y for an I & M program (county should pay, $10-$20, $20-$30, or $30-$40)?

4) Do you think all of your cars would pass such a test (would pass, some would pass, would not pass)?

5) How many vehicle and license d drivers are in your household?

6) What are you willing to do to reduce vehi cle miles traveled ( nothing, car pool, public transit, alternative transportation, trip c onsolidation, stay home ) -- you may pick more

than one?

7) What is your home’s primary source of heating?

8) Are there any additional sources of heating in your hom e? If so, what are they?

9) Do you comply with Cache Valley’s curr ent “No-Burn” days ( not applicable, never comply, mostly comply, always comply)?

10) Have you experienced a respiratory illn ess during Cache Valley’ s elevated pollution episodes (yes or no)?

The student survey questions asked for th e number and year of cars, what county each car is registered in, and what could be considered a “reasonable” price for emission44 Cache Valley Air Pollution Problem

17%

15%

27% 19% 22% Not a Problem

Small

Problem

Medium Problem Large

Problem Se v e r e Pr ob l e m inspections. The results from this survey ma y be more biased sin ce all students have a somewhat similar background and “stage-of-life” status.

THE SURVEY RESULTS

The Residents Phone Survey

The phone survey showed Cache Valley’s opinion and desires for solving the air quality problem. Figure 33 shows a fairly even spread of opinions concerning the severity of the problem. The combination of severe problem and large problem account up to 41% of the population compared to 32 % th at believe there is no problem or a small problem.

Figure 33. Q1: How severe is Cache Valley’s air pollution problem?

Figures 33 and 34 illustrate the publics accep tance of an I & M program in Cache Valley and how much they would be willing to pay for it. Seventy four percent (74%) of the residents surveyed would support an I & M program and 54% would pay $10-$20, while 19% would pay $20-30$. It should be noti ced that the percentage of people that would not support an I & M program (26%) is close to the percent of people who would prefer that the county tfund such a program ( 23%). This would likel y indicate that those who would not support an I & M program, would prefer the county to pay for it. Figure 35 shows that most of the surveyed residents (82%) believed all of their vehicles would pass and I & M test, while only 2% be lieved there vehicles would fail.

Question 5 (How many vehicle and licen sed drivers are in your household?) resulted in a ratio of 1.10 cars per licensed driver.45 Support for a Vehicle Emisions Program

74% 26%

Would Support Would not Su pp ort

Public Acceptance of Cost

54%

19% 4% 23%

$10-$20 $20-$30 $40-$30 County Should
Pay

Percentage of Cars In Household That Would Pass IM

82% 2% 16%

Would Pass Would Not Pass Some Would Pass Figure 33. Q2: Would you support a ve hicle emissions program?

Figure 34. Q3: How much would you be willing to pay?

Figure 35. Q4: Do you think all of your cars would pass?46 Percentage of People Willing to Reduce Vehicle Miles Traveled (VMT ) through...

45% 36% 54%

40%

5% 66%

0% 20% 40% 60% 80%Car PoolPublic Trans.AlternateTrans.TripConsolidationStay HomeNone The public’s acceptance of alternative wa ys to reduce Vehicle Miles Traveled (VMTs) was fairly evenly distributed betw een the presented options with only 5% of surveyed participants not willing to reduceV MTs (see Figure 36). This gives the County another option for increasing ai r quality in the valley by promoting items such as public and alternative transportation, and car pooling

Figure 36. Q6: What are you willing to do to reduce VMTs?

Figures 37, 38 and 39 illustrate the public ’s means of heating their homes and compliance with county policies. Most all hom es are primarily heated with a gas furnace (94%), while very few have a secondary source (total of 40%). Of the secondary sources, however, 27% were coal or wood burning st oves, the only heating source presenting a potential air quality problem. Of the all the people surveyed, 30% mostly complied with no burn policies, 11% always complie d (59% were not applicable).

The final question asked if they had ever encountered any respiratory problems caused by the air quality in the valley and 11% of the people said they had (see Figure 40).47 Primary Home Heating Utility

94% 6%

Furnace Other

Figure 37. Q7: What is your home’s primary source of heat?

Secondary Home Heating Utility

13% 60% 27% Wood or Coal
Burning Fire Place

Other No Extra Source

Figure 38. Q8: Are there any additional sources of heating in your home?

Compliance With No Burn Days

0% 59% 30%

11% Not Applicable Always Comply Mostly Complies

Never

Com p l y

Figure 39. Q9: Do you comply with “no Burn” days?48 Number of Vehicles per Student

0

1%

1

49% 2

41% 3

6% 4

3% Experienced an Air Po llutant Illness in Cache
Valley

11%

89% Yes

No

Figure 40: Q10: Have you ever ex perienced a respiratory illn ess during Cache Valley’s elevated pollution episodes?

The Student Survey

The CEE 3610 Environmental Management class was surveyed with 79 students in attendance. The responses to the survey questions are sh own in Figures 41 through 44. The average number of cars per student was calculated at 1.59 , with one student responding that he/she did not own a car.

Figure 41. Number of vehicles per stude nt (% of 79 students surveyed).49 Figure 42. Student vehicles by age bin.

Vehicle Registration Location

65% 13% 22% Cache County

Counties with I/M Programs

Counties without I/M Programs

Figure 43. Student vehicle re gistration location. Vehicles by Year

< 1980

5%

1980 - 1984

3%

1985 - 1989

13%

1990 - 1995

33% ≥ 1996

46%50 Reasonable Price Responses

74% 16% 0% 10%

$10 - 20

$20 - 30

$30 - 40

County pays

Figure 44. Student responses to reasonable I & M costs

The student survey results varied from pub lic phone surveys in responses to cost for an I & M program. Seventy four percent (74%) of students agre ed to pay $10-$20 for a program would be reasonable, while the publ ic percentage was 54% (refer to Figure 34 and 44). This could possibly be due to the av erage student income is significantly lower than the public average.

The number of vehicles used per student (n ot vehicles per lice nsed driver) can be evaluated in that, the majority of students (49%) used only one car and the next largest category being two cars. This can be explai ned by the percentage of married and single students in USU’s engineering pr ogram. It can likely be as sumed that the percentage of students with two cars are married (vehicles/ dr iver = 1) and the sing le students have only one vehicle. The age of vehicle distributi on between students and the general public are

almost identical

SURVEY CONCLUSIONS

Based on the above survey, the Cache Count y residents believe a significant air quality problem exists in the Cache Valley (68%) and ar e in support of a vehicle inspection and maintenance progr ams (54%). Furthermore, th ey would be willing to pay $10-20 for this service (74%). The public is also willing to take other measures to cut

down on vehicle miles traveled in order to cut down on vehicle pollution. These measures include trip consolidation (66%), alternate transporta tion (54%), and car pooling (45%).51 

### VERTICAL TEMPERATURE PROFILE MEASUREMENT

Contributing Authors

Dr. Randal S. Martin Kori D. Moore, B.S. Env. Eng. student Dept. of Civil & Environmental Engineering Utah State University Logan, UT52 INTRODUCTION

In order to better understand the invers ions that occur in Cache Valley, small

HOBO ® H1 temperature sensors/data loggers were deployed beginning in the spring of

2003 at selected elevations al ong an east-west transect from the valley floor up a steep mountainside to a point above the expected inversion heights. Through the use of the data loggers, the esta blishment, growth, and duration of inversions within Cache Valley were monitored over the period of one year. Data analysis shows the presence of lowlevel radiation inversions with diurnal and seasonal variations in the shape, steepness, and longevity of the vertical temperature profile. Comparison with measured PM 2.5 values has shown a strong correlation between the dur ation of a temperature inversion and the

ambient PM 2.5 concentration.

Background

Cache Valley is part of the transition between the basin and range topography of

Nevada and Utah and the mount ainous topography of the Rocky Mountains. It has a total area of about 300 square miles. Cache Valley is bounded on the west, south, and east sides by mountains and by hills on the north. Th e valley floor has an average elevation of 4500’ asl, and the surrounding mountains reach a height of 9900’ asl. The surrounding topography essentially creates a protect ed pocket or bowl of Cache Valley.

In a normal vertical temperature profile of the atmosphere just above the earth’s surface, temperature decreases with increasing altitude. In such conditions, turbulence and wind can readily mix a given pollutant thro ughout the vertical profile. A temperature inversion, on the other hand, is a positive change in temperature with increasing altitude, or can be defined as a layer of lighter, warmer air on top of a layer of more dense, colder air. The warm air essentially places a cap on the lower air, trapping below the colder air and any pollutants therein. If the inversion pe rsists, the concentrati on of pollutants in the trapped layer of colder ai r increases as more polluta nts are added (Masters, 1998).

An example of an inversion is shown in Figure 45, obtained by driving up a canyon adjacent (east) to Cache Valley. There is a strong temperatur e inversion at about 5000’ asl for both sampling periods. Two importa nt things to note are that the sampling dates occur during the winter and that they are two years apart, suggesting the 5000’ asl mark is a common inversion depth. In Cach e Valley, winter-time temperature inversions

occur due to the reflection of the sun’s energy by the snow, wh ich allows the air above to warm up faster than the snow covered ground, thus creating a positive change in temperature with increasing altitude at a poi nt above groundlevel. High pressure cells create extended periods of clear skies, a nd these clear skies comb ine with snow cover (high albedo) to produce strong temperature in versions over Cache Valley that can last for several days (see Figure 46). The surr ounding topography contains the colder air trapped below, much like air trapped in a closed jar. Pollutants released within the valley become concentrated, often causing a haze. A low pressure front is required to break a persistent inversion, and the precipitation that sometimes follows clears the air of most of the particulate matter.53 Cache Valley Vertical Temperature Profile

4500 5000 5500 6000

-12.0 -10.0 -8.0 -6.0 -4.0 -2.0 0.0

Temperature (C)Elevation (ft asl)

1/24/2002 1/12/2004

Figure 45. Temperature profile of Cach e Valley obtained by driving up

an ad j acent can y on.

METHODOLOGY

Typical measurements of temperature inve rsion heights, persis tence, and growth are achieved through the period ic release of radiosondes or the use of a tethersonde (Arya, 1999). A radiosonde consists of a small, light-weight radio transmitter connected to temperature, pressure, and humidity sensor s that are all attached to a helium-filled

balloon. The balloon is releas ed, and, as it ascends into the atmosphere, the radio Figure 46 . Cache Valley inversion as seen fr om an adjacent mountainside (ele. 6300’ asl). The city of Logan, UT is faintly seen in the center.54 transmitter sends the measured data back to a receiver connected to a computer which interprets the data a nd stores it. A tethersonde differs from a radiosonde in that the balloon is attached to the ground via a teth er. Sensor/transmitter systems may be dispersed along the tethering line, and may be used for longer periods of time than with a radiosonde. These methods provide very ti me-limited data, are time intensive, and require costly equipment. Other methods of obtaining inversion measurements include the use of acoustic and thermal adsorption t echniques, which provide more time resolved data, but require complex and expensive equipment and can be time-intensive.

There are currently several commercially available temperature sensors/data loggers that have been deve loped for both scientific and commercial uses (Whiteman et
al. , 2000). One such data logger, the HOBO ® H1 (Figure 47) developed by Onset Computer of Bourne, MA, is a small, inexpensive unit consisting of a circuit board in a plastic case; waterproof cases are available for protection from water and sunlight. A similar product of Onset Computer, the HOBO ® H8

Pro was found to be effective and accurate for meteorological applications by Whiteman et al. (2000).These systems require minimal attention and have a userfriendly software program. The HOBO ® H1 data loggers were used to measure temperature inversion characteristics in Cache Valley.

Nine HOBO ® H1 temperature sensor/data loggers were utilized to record ambient temperatures at separate locat ions and elevations. The sens ors/data loggers were first

calibrated to one another thr ough the use of four co-located sampling periods. Derived calibration equations were used to adjust each respective data set. Since the data collected were only compared to one another to obtain relative temperature differences and not to obtain the actual temperature, it was not necessary to calibrate the sensors/data loggers with a Hg-thermometer. The sensors measured the temperature on a continuous basis, and the hourly average temperature was stored as a data point. The data were collected every six to eight w eeks. The temperature sensor s within the protective case were placed 2-3 meters above ground and in open areas to minimize terrestrial heating and ensure ventilation, respectively. The el evation of each sensor was based upon site accessibility and vertical spacing, and the fina l elevations are as follows: 4562’, 4646’, 4865’, 5024’, 5338’, 5513’, 5735’, 6287’, and 6576’.

RESULTS

The HOBO ® H1 temperature sensors/data loggers obtained reliable data that were

used to determine the characteristics of te mperature inversions in Cache Valley. As a whole, they adequately measured the actua l ambient temperature when compared with available, nearby meteorological stations.

Figure 47 . HOBO ® H1 temperature sensor/data

l ogge r a n d p r otect i ve case.55 March 7-31, 2003 Hourly Avg Temp Profiles

4500 5000 5500 6000 6500 7000

0 2 4 6 8 10 12 14 16 Temperature (C)Elevation(ft asl)

3:00 AM 6:00 AM 9:00 AM Noon

3:00 PM 6:00 PM 9:00 PM Midnight

Figure 48 . Average vertical temperatur e profile of Cache Valley for March 7-31, 2003. The use of vertical temperature profiles averaged over a period of weeks or a month provides a good indication of the existenc e and characteristics of inversions, as can be seen by the average values for March 2003 in Figure 48. At 6:00 AM, just before the sun rises, there is a strong temperatur e inversion between a bout 4500’ and 5400’, but above that the temperature profile looks nor mal, except a possible existence of an upper

level inversion at 6300’. Afte r the sun rises, the valley floor begins to warm up, and by 9:00 AM the inversion is almost gone. As th e day progresses, the valley increases in temperature and at about 3:00 PM the temp erature profile almost mirrors the dry adiabatic lapse rate shown by the black dotted lin e. As the sun sets, the valley cools at a much faster rate than the air mass above, causing a temperature inversion to begin forming again before midnight. The cooling continues through the night as the diurnal evolution of the temperature profile comes to an end, completing the daily cycle. Also, note the broad range of temperature values ove r the entire profile. Similar results were produced through the analysis of data for spring, summer, and fall months.

On the other hand, if the averaged temper atures for the first half of January 2004 are examined, it is apparent that the temp erature inversion doesn’t form and break up each day, rather it is more diurnally consis tent (Figure 49). Only during the warmest times of the day is the inversion seemingly affected by the surface warming. The range of temperatures throughout the vertical profile is also much smaller than that of March 2003, especially at higher elevations. This w ould suggest that winter months have more persistent inversions, as the fi rst of January 2004 demonstrates.56 The data collected from the HOBO ® sensors also proved very useful in examining the day to day changes in the temperature inve rsion. This day to day change can be seen for the month of January 2004 in Figure 50, with red representing warm temperatures, getting brighter as the te mperatures grow warmer, a nd blue representing cold temperatures, growing brighter as the temperature decreases. It should be noted that the

value of 2 is the first numb er on the x-axis, but it really represents midnight between January 1 st and 2 nd ; there is not a day 32, instea d it is midnight of the 31 st . Early in January, data from the lowest sensor were not available, causing the blue patch on the

bottom until the 18 th

.

From Figure 50, it can be seen that duri ng the first couple of days of January 2004, it was fairly warm and no inversion was observed, or the cold air was above the warm air. However, the air temperatures dropped over several days and on about the 6 th
a temperature inversion began to appear, with warmer air above cooler air. As time progressed, the temperature difference be tween the air masses above and below increased, causing the temperatur e inversion to strengthen and become deeper. Just after the middle of the month, a couple of weak lo w pressure cells passed through the region, decreasing the temperature difference, but not completely breaking up the Cache Valley inversion. The inversion began buildi ng after each frontal system on the 18 th and the

23 rd . At the end of the month, a strong low pressure cell, with an accompanying snow storm, moved in to break up the inversi on and provide some relief from the 20-day capping lid sitting over Cache Valley. The te mperature profile returned to normal with

cooler air above and warmer air below.

Figure 49 . Vertical temperature profile over Cache Valley for January 1-17, 2004. Avg Temp Profile for January 1-17, 2004

4500 5000 5500 6000 6500 7000

-16.0 -14.0 -12.0 -10.0 -8.0 -6.0 -4.0 -2.0 0.0

Temperature (C)Elevation (ft asl)

3:00 AM 6:00 AM 9:00 AM Noon

3:00 PM 6:00 PM 9:00 PM Midnight57 Figure 50. Temperature contour map of the ai r above Cache Valley with respect to elevation and time for the month of January 2004. 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32

January 2004 4600 4800 5000 5200 5400 5600 5800 6000 6200 6400 6600Elevation (ft asl)

The temperature contour map clearly s hows the growth and persistence of the inversion layer. To examine the affects of an inversion on the pollution concentration,

the PM 2.5 concentrations for the month of Janua ry 2004 were overlaid on the temperature contour map in Figure 51. The solid yellow line represents the ambient PM 2.5 concentration as measured at the Logan city sampling location and the dotted green line represents the National Ambient Air Quality Standard (65 μ g/m 3 ). The concentration of

ambient PM 2.5 began fairly low, but as the temperature inversion started and strengthened, the concentration reached values double the national standard. Concentrations dropped when the inversion laye r begins to break up due to the two weak low pressure systems, but continued to increase after each system passed. It was not until the strong low pressure system passed thr ough at the end of the month that the PM 2.5 concentrations dropped below the NAAQS.58 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32

January 2004 4600 4800 5000 5200 5400 5600 5800 6000 6200 6400 6600Elevation (ftasl)

65 μ g/m 3

Figure 51

. January 2004 temperature contour map with PM 2.5 concentration (yellow) and National Ambient Air Quality Standard (green)

.

CONCLUSIONS

The HOBO ® H1 temperature sensors/data l oggers were able to distinguish differences in the Cache Valley vertical temp erature profile, incl uding the evolution of temperature inversions. De spite being ground-based, the se nsors/data loggers were sensitive and accurate enough to produce relia ble data. Through data analysis, it was been found that diurnally fluctuating inversions dominate the vertical temperature profile for all but the colder months of winter, su ch as December, January, and February. The sensors/data loggers proved extremely useful in understanding the evol ution of persistent

inversions that occur in Cach e Valley, as well as clearly de monstrating their effects on

ambient PM 2.5 concentrations. This understanding will allow for better prediction of high pollution events and, therefore, aid in curre nt and future pollution prevention efforts.59 

### INDOOR/OUTDOOR PARTICULAT E MATTER IN THE CACHE

VALLEY

Contributing Authors

Dr. Randal S. Martin Kori D. Moore, B.S. Env. Eng. Student Vishal Doshi, M.S. Env. Eng. Candidate Dept. of Civil & Environmental Engineering Utah State University Logan, UT60 INTRODUCTION

The health concern for PM 2.5 is because the particle s are small enough to be breathed into the deep lung tissue and become deposited. Larger particles are filtered out

in the nose and throat. The affects of the deposited particles depend on particle composition, dose, and the current health status of the individual. Daily (24-hr) averaged

PM 2.5 levels as high as 133 and 138 μg/m 3 in the Cache Valley have been recorded during prolonged wintertime temperature inversions. Such high levels are strictly a winter-time problem for Cache Valley, as can be seen in Figure 52. During the spring, summer, and fall, the average is around 10 μg/m 3 . As previously discussed in earlier sections, chemical analysis of the PM 2.5 in Cache Valley has shown that it is dominated by ammonium salts, which contribute 60-90% of the total particle mass, and that ammonium nitrate (NH 4 NO 3 ) is the largest fraction by mass (Martin and Zhu, 2004; UDAQ, 2006). Ammonium salts are secondary po llutants as they form in the atmosphere through photochemical reactions, such as is generalized in the following:

NH 3 (g) + HNO 3 (g) ÅÆ NH 4 NO 3 (s) (Equation 1)

As this is an equilibrium reaction, temp erature greatly affects the formation, or dissociation, of ammonium nitr ate, causing a difference in K eq values of greater than two orders of magnitude between 0 and 20oC. Solid particles are favored at cold temperatures and gases are favored at warm temperat ures (Seinfeld and Pandis, 1998).

0 20 40 60 80 100 120 140

1/1 1/31 3/1 3/31 4/30 5/30 6/29 7/29 8/28 9/27 10/27 11/26 12/26μg/m3

2001 2002 2003 2004 A nnual Average PM 2.5 Standard 24-Hr PM 2.5 Standard

Figure 52 . Cache Valley PM 2.5 concentrations as recorded for 2001-2004.61 The average adult begins to feel the health affects of PM 2.5 at 65 μg/m 3 , but those with compromised immune systems such as children, the elderly, and the ill may have noticeable affects at 40 μg/m 3 . The Bear River Health Department (BRHD), in conjunction with the Utah Department of Air Quality (DAQ), has developed a public notice system to alert citizens of Cache Valle y of the current air quality during winter months using the following color scale: “gr een” – good air quality, continue activities as normal; “yellow” – poor air quality, reduce ve hicle mileage and those with compromised immune systems are recommended to remain indoors; “red” – bad air quality, reduce vehicle mileage and everyone is recommended to remain indoors. The PM 2.5 concentrations that divide green and yellow and yellow and red are 40 and 65 μg/m 3

, respectively. The BRHD also suggests that school children remain inside during recess and lunch time on red days. However, the qual ity of the indoor air, with respect to PM 2.5 , in comparison to the ambient air quality in the area schools was unknown. Therefore, it

was also unknown if it was act ually better to keep the ch ildren inside on high pollution days. This study was designed to determine the indoor air quality and answer the question as to whether it is best to keep the children inside or not.

Past research on indoor air quality vers us outdoor air quality has shown that

indoor PM 2.5 is usually less than outsid e, ambient levels. Sawant et al . (2004) found that

indoor:outdoor ratios of PM 2.5 concentrations in schools in Mira Loma, CA during the fall of 2001 and winter of 2001-2002 averaged 38 %. Chemical analysis further showed that the highest portion of PM 2.5 was organic carbon and that the indoor:outdoor ratio of

nitrate was the smallest of a ll the chemical species (Sawant et al. , 2004). El-Abssawy (2003) confirmed that indoor particle concen trations were depende nt on outdoor particle concentrations, indoor activities , and on particle size.

Based on these past studies and owing to the dominance of ammonium nitrate in

the local PM 2.5 , it was expected that local PM 2.5 concentrations would be lower indoor as compared to outdoor. Therefore, a study was initia ted to examine any such differences.

METHODOLOGY

Three elementary schools and one high sc hool in Cache Valley were chosen as sampling sites. Filter-based sampling was conducted using 0.45 μm Teflon filters with AirMetrics MiniVol impaction samplers. Pair ed samplers were placed both inside and outside of each school, as seen in Figure 53, and operated at simultaneous times to obtain comparable data. Sample times were duri ng school hours, Monday through Friday from

8:00 AM to 4:00 PM local time and were coll ected over two to four day periods. Table 2 lists the school name, the location of both samplers, and the sampling dates. The UDAQ sampling site is located one block from Loga n High School. The filters were analyzed for mass by comparing average pre-weights a nd post-weights. An ion chromatography was performed on solutions of the co llected particles for nitrate (NO 3 - ), sulfate (SO 4 - ), nitrite (NO 2 - ), and chloride (Cl - ).62 Airmetrics MiniVol TM Portable Air Sam p le r

Figure 53 . PM 2.5 samplers at Greenville Elementary a) in the library and b) on the roof.

School Sample Dates Sampler Location Inside Library Greenville Elementary Jan. 24, 2005 – Feb. 18, 2005 Outside Roof Inside Library Summit Elementary Jan. 11, 2005 – Feb. 11, 2005 Outside Roof Inside Library Sunrise Elementary Jan. 11, 2005 – Feb. 8, 2005 Outside Roof

Inside Classroom Logan High

School Feb. 9, 2005 – Feb. 25, 2005 Outside UDAQ Sampling

Site

Table 2 . Sampling locations and dates by school.

RESULTS AND DISCUSSION

The results of the mass concentrat ion analysis from both the indoor and outdoor samplers for each school are shown in Figure 54. The linear fit and R 2 value for

each data set are also shown. Examination of the data show that while outdoor PM 2.563 Figure 54 . Indoor air quality versus outdoor air quality for all four schools. Indoor vs. Outdoor PM 2.5 Concentrations

y = 0.1557x + 11.286

R 2 = 0.5088 y = 0.0765x + 6.2655

R 2 = 0.2436 y = 0.1403x + 5.7243

R 2 = 0.9724

y = 0.0427x + 10.286

R 2 = 0.0856 0 5 10 15 20 25

0 10 20 30 40 50 60 70

Ambient PM 2.5 ( μ g/m 3 )Indoor PM2.5(μg/m3)

Summit Sunrise Greenville

Logan H.S. Linear (Summit) Linear (Sunrise)

Linear (Greenv ille) Linear (Logan H.S.) levels nearly reached the 24-hr NAAQS of 65 μg/m 3 , the indoor concentration at each of the four schools was well below the 40 μg/m 3 at which sensitive populations are suspected to be affected. In the data fo r Logan High School, one apparent outlying value

caused a low R 2 value, but the data are otherwise well grouped. Without the outlier, an

R 2 value of 0.5747 would be produced. The low slope values in the linear fit equations suggest that the indoor PM 2.5 is slightly affected by the outside concentration, but that

most of the PM 2.5 is apparently removed.

The average measured ambient and indoor PM 2.5 concentrations are shown in Figure 55, along with the ratio of the indoor levels to the outdoor levels as a percent. The

error bars show the 95% confidence interv als for each average value. The average

outdoor concentrations for each school were not found to be statistically different from one another. The high variabil ity seen in the outdoor values is expected due to changes in ambient temperatures and in the vertical mixing ability of the ground-level air mass caused by vertical temperature inversions, and by deposition of the particles during precipitation events. The indoor PM 2.5 concentrations are fairly constant as demonstrated by the low variability. Sunrise Elementa ry, Greenville Elementary, and Logan High School indoor averages were statistically the same, but Summit Elementary had a64 Concentration and Ratio Averages

0 10 20 30 40 50 60 70 80 90

Ambient Indoor I:O RatioConc. (g/m3) or I:O Ratio (%)

Summit Sunrise Greenville Logan HS

Figure 55 . Average PM 2.5 levels and indoor:out door ratio by school. statistically significant higher average con centration than the other three. Summit Elementary also had the highest average i ndoor:outdoor concentrati on ratio at 61.2%. This, however, was not statistically differe nt than the average for both Greenville Elementary and Logan High School. The aver age indoor:outdoor concentration ratio for Sunrise Elementary was not statistically di fferent than the averages for Greenville Elementary and Logan High School, but was sign ificantly different from the average of Summit Elementary.

It is believed that the mechanism used by the heating system in each school may

affect the indoor PM 2.5 concentrations. Greenville Elementary, Sunrise Elementary, and Logan High School heat the buildings by passi ng air through a heater and blowing the heated air throughout the build ing (central heating). Summit Elementary uses steam

heaters to heat the air in some of the rooms, producing less air circulation than the other

schools. Circulation of the h eated air provides a more unifo rm air temperature and mixes suspended particles more uniformly as well. As mentioned earli er, air temperature greatly affects the formation and volatilizati on of ammonium nitrate. The difference in heating mechanisms between Summit Elementary and the other three schools would have an affect on the total particle mass due to the volatilization of a mmonium nitrate.

The chemical analyses of the particle s collected on the filters through anion chromatography confirmed that nitrate dom inates the outdoor particle composition (Figure 56). It also revealed th at the average concentration of NO 3 - in the indoor air of65 Figure 56 . Anion concentrations in indoor and outdoor PM 2.5

. Average Anion Concentration and Indoor:Outdoor Ratio

0 1 2 3 4 5 6 7 8 9

Chloride Nitrate SulfateConcentration (μg/m3) or Ratio

Indoor Outdoor I:O Ratio the three elementary schools was six times less than the outdoor concentrations, producing an average indoor:outdoor nitrate co ncentration ration of 17%. The indoor and outdoor nitrite (NO 2 - ) levels were below the method detection limit. The particulate

concentration of Cl - was twice as high indoors as outdoor s, which could be due to sources within the building. The SO 4 - concentrations were much closer than either the NO 3 - or the Cl - with an average indoor:outdoor ratio of 85%. Cation chromatography was not performed because the complimentary cation for SO 4 - and NO 3 - is believed to be ammonium (NH 4 + ). The differences in the indoor :outdoor particle composition ratios between elementary schools is found in Figur e 57. Due to the dominance of ammonium nitrate in the particle mass, only the NO 3 - anion indoor:outdoor ratio was examined. The error bars represent the 95 % confidence interval. Th e average indoor:outdoor NO 3 - ratios are not statistically different with the small number of data points collected, but there appears to be an higher concen tration trend in data collected at Summit Elementary, the

school that uses steam heaters to heat the building. More da ta collection at all sites is required to more completely quantify any difference in NO 3 - levels.66 Figure 57 . Average nitrate indoor:out door ratios for the Elementary

Schools A

verage Nitrate Indoor:Outdoor Ratio for Elementary Schools

Summit Sunrise Greenville 0 0.05

0.1 0.15

0.2 0.25

0.3 0.35

0.4 0.45

0.5Ratio

CONCLUSIONS

Winter-time PM 2.5 concentrations above the nati onal standard in Cache Valley have led area schools to keep children insi de during recess and lunch time on “red” days as suggested by the Bear River Health Department. Indoor PM 2.5 concentrations versus

ambient PM 2.5 were studied in four area schools a nd chemically analyzed in order to quantify indoor concentrations and particulate composition.

The average measured indoor PM 2.5 concentrations at the four schools was 12.5 μg/m 3 , well below the 40 μg/m 3 level at which children start to be affected, even when ambient concentrations approach and exceed the national standard of 65 μg/m 3 . Anion analysis of the collected pa rticles confirmed that ammonium nitrate is the dominant chemical species in ambient PM 2.5 , but the indoor NO 3 - concentrations are on average

17% of the outdoor concentratio ns. This difference in NO 3 - concentrations is likely due

to ammonium nitrate volati lization as the temperature increases from ambient temperature to room temperature. The indoor PM 2.5 levels were, therefore, found “safe”

in all four schools at the ambi ent concentrations measured. Keeping the children inside during high pollution days was in their best in terest and protected them from exposure to unhealthy levels of particulate matter.67 

### WINTERTIME VERTICAL OZONE DISTRIBUTIONS

Contributing Authors

Dr. Randal S. Martin Crystal Viator, B.S. Env. Eng. Student Dept. of Civil & Environmental Engineering Utah State University Logan, UT68 INTRODUCTION

Research discussed in previous sections showed that the main contributor to the

PM 2.5 in the Cache Valley was photochemically derived ammonium-nitrate (NH 4 NO 3 ). Along with the precursor compounds of ammonia (NH 3 ) and oxides of nitrogen (NO

x ),

the formation of ammonium-nitrate is fueled by ozone and sunlight. Although considerably more reactions are invo lved, Equations 1-4 show the basic NH 4 NO 3 formation mechanisms.

O 3 + sunlight → O 1 D + O 2 (Eq 1)

O 1 D + H 2 O → 2OH (Eq 2)

OH + NO 2 → HNO 3 (Eq 3)

HNO 3 + NH 3 → NH 4 NO 3 (Eq 4)

As shown above ozone (O 3 ) reacts with available incoming so lar radiation (i nsolation) of about 310 nm, or less, to form O singlet D (O 1 D), an excited oxygen atom, as well as diatomic oxygen (O 2 ). The O 1 D then reacts with water vapor to form two hydroxyl radicals. Hydroxyl radicals are highly reac tive and readily combin e with any available nitrogen dioxide (NO 2 ), produced from car emissions a nd other combustion sources, to give nitric acid (HNO 3 ), which when combined with gas-phase ammonia forms NH 4 NO 3. Furthermore, ozone is known to accelerate the oxidation of hydrocarbons and other pollutants in quantities as low as 20 ppb whic h can complicate and accelerate the above reactions (Woods Hole, 2006).

Ozone is also the product of a complex series of reactions strongly dependent on available sunlight ( ≤ 420 nm) as summarized in Equation 5:

NO 2 + NMHCs + sunlight → O 3 + products (Eq 5)

where NMHCs represents non-methane hydroc arbons. Typically these reactions are expected to be dominant in the summertime when there is plenty of available sunlight. However, Cache Valley’s global location (41.8°N) and frequent wintertime clouds, storms, and fog episodes, were not thought to allow enough insolation to produce enough ozone or to adequately drive Equations 1 and 5.

Uncertainty in the local wintertime ozone levels led investigators (Dr. Martin) to establish an ozone monitoring site in downt own Logan, situated in the heart of Cache Valley, from February to April of 2004. Prev iously, ozone had only been monitored in Logan for regulatory purposes by the Utah Division of Air Quality (UDAQ) during the summer months; however, since the brief st udy of Martin, the UDAQ has established year-round ozone monitoring at the specifi ed location. As shown in Figure 58, wintertime ozone concentrations peaked as high as 70 ppb, with average peak values69 0 10 20 30 40 50 60 70 80

1/30 2/4 2/9 2/14 2/19 2/24 2/29 3/5 3/10 3/15 3/20 3/25 3/30 4/4 4/9 4/14 4/19 4/24 4/29Ozone (ppb)

Ozone Daily O3 Avg around 45-55 ppb. The overall daily averages were on the order of 25-35 ppb. These unexpectedly high wintertime ozone values i ndicate sufficient oxidation potential to initiate the previously discussed reaction pa thways toward ammonium nitrate formation (Refer to Equations 1-5).

The source of the observed high concentrations of O 3 was still uncertain, particularly in regards to th e lack of available insolation. However, somewhat in support of these high wintertime values Lefohn et al. (2001) reported finding hourly average ozone concentrations greater than or equal to 50 and 60 ppb during photochemically quiescent months in the winter and spring at several rural sites acr oss southern Canada, the northern United States (Wyo ming), and northern Europe.

Figure 58 . Logan O 3 February-April 2004.

For the Cache Valley situation, it was speculated that free tropospheric ozone could be the source of the elevated ground level ozone, assuming the possibility or likelihood of sufficient downward mixing. As such, an experiment was designed to measure the local wintertime vertical ozone pr ofile. If elevated concentrations were observed above the ground level or the invers ion heights, the upper level ozone may be the source for the unexpectedly high concentra tions recorded at the Logan station.

METHODOLOGY

In order to measure the vertical ozon e concentrations a small airplane was outfitted with an ozone monitor, a temperat ure monitor, a GPS system, and two flights were conducted. The first flight was in the mid-afternoon of February 9, 2006 (13:41- 15:32). The second flight was in the early mo rning, just after sunrise, on February 11, 2006 (7:02-8:59). A four meter Teflon tube with an outer diameter of 1⁄4” was attached to70 the wing strut of a Cessna 182 airplane. The tu be ran to the inside of the plane and was

attached to a ThermoEnvironmental Model 49C UV Photometric O 3 Analyzer. Before the initial flight, the ozone monitor was ca librated using a ThermoEnvironmental Model 49C Primary Standard O 3 Calibrator. The data were av eraged over one minute intervals and corrected for system sampling and instru ment response time lags (approximately one minute). A HOBO temperature sensor wa s attached to the opposite strut and programmed for 15 second averaging periods. A Garmin Etrex Vista handheld GPS was used to track aircraft position and altitude. The flights were on a north-south transect along the length of the valley at above sea level elevati ons of around 1460 m, 1600 m, 1950 m, and 2770 m, or above the valley floor elevations of approximately 90 m, 300 m, 600 m, 1400 m. A sample flight path (Februar y 9) can be seen in Figure 59. The flight path for the second profile (F ebruary 11) was similar.

Flight Path (2/9/06)

1300 1500 1700 1900 2100 2300 2500 2700 2900 3100

4590 4600 4610 4620 4630 4640 4650 4660 4670
UTM(N); kmElevation (m asl)

Figure 59 . Flight path for February 9, 2006.

RESULTS

During the first flight ground level ozone concnetrations measured just before takeoff and after landing, were found to average approximately 35 ppb. At the UDAQ Logan station, approximately 5.6 km from th e airport location, dur ing the same time period ground level ozone was measured to be approximately 34-48 ppb (UDAQ, 2006). The ozone concentrations along the flight pa th are shown in Figure 59. The different elevation transects above the valley floor ar e shown in different colors (see legend on Figure 59). For most of the elevations fl own, ozone concentrations were moderately consistent varying between 40-50 ppb. Howeve r, at the lower two transects, 90 m and 300 m above ground level, the ozone concentr ations displayed a noticeable decrease when flying over the mid-to-south end of the valley, the most densely populated area of the valley. Additionally, it should be noted that there was a 1.4 – 1.9 m/s wind blowing out of the Northwest. The investigators theo rize that the reason the “Logan Dip,” as it was referred to, was not seen at the third and fourth tr ansects (600 m – 1400 m) is

because these final two transects were above the inversion height . Figure 60 shows a71 photograph taken from an elevation of appr oximately 1900 m (asl) clearly showing the inversion layer.

Ozone Concentrations Along the Flight Path (2/9/06)

25 30 35 40 45 50 55 60

4590 4600 4610 4620 4630 4640 4650 4660 4670
UTM(N); kmOzone (ppb)

90 meters 300 meters 600 meters 1400 meters

Figure 59 . Ozone concentrations along February 9, 2006 flight path (elevation transects are above ground level).

Figure 60 . Photograph of invers ion above Cache Valley, Ut ah taken 2/9/06 at 1900 m (asl).

The valley-wide average vertical ozone pr ofile from the same day is shown in Figure 61. The ozone concentrations were low at ground level and rose to values approaching 50 ppb, then began to decrease at above sea level el evations of around 2000 m. The 95% confidence intervals have a highe r degree of variability at lower elevations. This coincides with the variability owing to the “Logan Dip” seen in Figure 59.72 However, above the inversion layer the 95% confidence intervals ar e small because the ozone was essentially the same horizontally (north-to-south) through the measured troposphere.

Cache Valley Vertical Ozone Profile-Flight 2/9/06

1300 1500 1700 1900 2100 2300 2500 2700 2900 3100

10 20 30 40 50 60 70

Ozone (ppb) and Temp (F)Elevation (m asl)

Temperature Ozone Avg O3 Avg Temp

Figure 61. Vertical temperature and ozone profile February 9 flight (error bars represent the 95% confidence interval).

Also shown in Figure 61 is the vertical temperature profile for the February 9 th
flight. As described by Cooper and Alley ( 2002), an inversion is when temperature increases with altitude as opposed to the typical case of temperature decreasing vertically. A very pronounced inversion can be seen clearly delineated at approximately 650 m above ground level (2000 m asl). Most of the locally emitted reac tive pollutants remain trapped under the inversion laye r and are more concentrated at the south end of the valley due to population density and wind direction. This is also evidenced by the “Logan Dip” in Figure 59.

The second flight in the early morn ing of February 11, 2006 found that ground level ozone was between 16-31 ppb. UDAQ repor ted that on that morning the Logan station ground level ozone was measured to be approximately 19-33 ppb (UDAQ, 2006). The ozone concentrations along the flight pa th are shown in Figure 62. As with the previous flight (Figure 59) the different el evation transects above the valley floor are shown in different colors (Figure 62). On the morning of the 11 th , ozone concentrations were more consistent in regards to north-so uth variability and generally increased with

elevation.73 Ozone Concentratons Along the Flight Path (2/11/06)

10 20 30 40 50 60 70

4590.000 4600.000 4610.000 4620.000 4630.000 4640.000 4650.000 4660.000 4670.000
UTM(N); kmOzone (ppb)

90 meters 400 meters 600 meters 1400 meters

Figure 62. Ozone concentrations along February 11, 2006 flight path (elevation transects are above ground level).

Figure 63 shows the vertical temperature and ozone profiles for the February 11 th flight. As elevation increased, there was a gradual increase in ozone up to approximately the same background concentration as observed on the February 9 th afternoon flight. Once again the observed ground level ozone showed the highest degree of variability, which is likely due to different concentrations observe d between the start (take-off) and ending (landing) of the flight period.

Cache Valley Vertical Ozone Profile-Flight 2/11/06

1300 1500 1700 1900 2100 2300 2500 2700 2900

0 10 20 30 40 50 60 70

Ozone (ppb) and Temp (F)Elevation (masl)

Temperature Ozone Avg O3 Avg Temp

Figure 63 . Vertical temperature and oz one profile February 9 flight.

This flight started before sunrise, at which point ground level ozone had had sufficient time overnight to titrate out by reacting with hydro carbons and oxides of nitrogen. Upon landing the sun had risen a nd ozone formation chemistry had already74 begun (more insolation). The temperature prof ile (Figure 63) showed that there was a moderate, continuous inversion from gr ound level to the highest elevation.

CONCLUSIONS

Upon analysis of the data it was concl uded that the wintertime high levels of ozone in Utah’s Cache Valley could indeed be a result of downward mixing from ozone aloft. The upper-level available ozone is like ly being utilized at gr ound level, as well asproduced, through the previously mentioned photochemical reactions to form particulatephase ammonium nitrate.

Figure 64 directly compares the ozone c oncentrations from both flights. The ground level ozone was low in the morning hours compared to the afternoon flight due to reactions previously discussed.

Ozone Cocentrations

1000 1500 2000 2500 3000

0 10 20 30 40 50 60 70

Ozone (ppb)Elevation (m asl)

Feb 9 Afternoon Feb 11 Morning Ave O3 2/9/06 Ave O3 2/11/06

Figure 64 . Ozone Concentration-both flights.

In the afternoon, a very pronoun ced dip in ozone concentra tions over Logan served as evidence that the ozone is reacting with po llutants within the i nversion boundary. The ozone concentrations were similar (45- 55 ppb) above the inversion and generally increased with elevation. Although this study gives strong in dication that free tropospheric ozone may supply sufficient con centrations to initi ate photochemical reactions in Northern Utah’s Cache Valley, it is recommended that additional vertical ozone profiles be measured to determine if these results are typica l throughout the winter period. Airplane transects are expensive and ti me consuming. It is suggested that other methods, such as radio sondes or tether sondes, be used for further analysis.7576 Cache Valley Major Carbonyls (Winter 2005)

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

"Bad" Air Averages

Formal (A) Formal (L) Acetal (A) Acetal(L) Aceton (A) Aceton (L) 

### VOCs

Cache Valley Major Carbonyls (Winter 2005)

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

"Good" Air AveragesAmbient (ppb)

Formal (A) Formal (L) Acetal (A) Acetal(L) Aceton (A) Aceton (L)77 1 10 100 1000 10000

Gas-Phase NH 3 (ppb) Grocery Store General Store

Restaurant USU CEE Dept Grade School

BRHD (gov) Beutler Home Martin Home Dupont Home KDM Apt JTP Home 

### NEW RESEARCH

Indoor NH3, Valley-wide NH3

Jan. 20-25, 2006

415000.00 425000.00

UTM (NAD27); m 4610000 4615000 4620000 4625000 4630000 4635000 4640000 4645000 4650000 4655000 4660000UTM (NAD27); m

Logan Franklin, ID Preston, ID

Mendon Cronish, UT

Newton
Smithfield

Wellsville

Trenton

Cutler

Reservoir78 

### REFERENCES

40CFR50, Title 40 Code of Federal Regulatio ns, Part 50, Appendix L (2003), Reference

Method for Determination of Fine Particul ate Matter as PM2.5 in the Atmosphere, www.access.gpo.gov/nara/cfr/waisidx_03/40cfr v2_03.html, accessed December 2003.

40CFR50, App. F (2006), Title 40 Code of Fede ral Regulations Part 50, National Primary and Secondary Ambient Air Quality Standard s, Appendix F, Measurement Principle and

Calibration Procedure for the Measurement of Nitrogen Dioxide in the Atmosphere,

accessed at washingtonwatchdog.org/documen ts/cfr/title40/part50.html

.

AirMetrics (2004), MiniVol Portable Air Sampler Operators Manual, www.airmetrics.com/products/miniv ol/index.html, accessed January 2004.

Ansari A.S.and S.N. Pandis (1999), Predicti on of multicomponent inorganic atmospheric aerosol behavior, Atmos. Environ ., 33:745-757

Arya, S. Pal (1999), Air Pollu tion Meteorology and Dispersion , Oxford University Press, Inc.: New York City, NY. 310.

Blanchard, C.L., P.M. Roth, S.J. Tanenbaum, S.D. Ziman, and J.H. Seinfeld (2000), The Use of ambient measurement to identify wh ich precursor species limit aerosol nitrate formation, J. Air Waste Manage. Assoc ., 50:2073-2084.

Cache County (2004), Utah, Assessor’s Offi ce, Motor Vehicle Registration, personal

communication.

CAEAAFO (2002), The Scientific Basis for Es timating Emissions from Animal Feeding Operations, Interim Report, Committee on Air Emissions from Animal Feeding Operations, Division of Earth and Life Sciences, National Research Council, National Academy Press.

CENR (2001), Atmospheric Ammonia: Sources and Fate, A Review of Ongoing Federal Research and Future Needs, Committee on th e Environment and Natural Resources, air Quality Research Subcommittee, NOAA Aer onomy Laboratory, Boulder, CO, June 2000.

Cooper, D.C. and F.C. Alley (2002), Ai r Pollution Control: A Design Approach

, Waveland Press, Inc., Prospect Heights, Ill., U.S.

Cowen, K., A.L. Sumner, A. Dindal, K. Riggs, Z. Willenberg, J. Hatfield, R. Pfieffer, and K. Scoggin (2004), Thermo Electron Cor poration Model 17C Ammonia Analyzer, Environmental Technology Verification Re port, ETV Advanced Monitoring Systems Center, Battelle, Columbus, OH, July 2004.79 El-Abssawy, A.A. (2003), Indoor-outdoor relati onship of suspended particulate matter and its chemical compositi on at different sizes, Intern.l J. of Environ. and Pollut. , 19:

615-634.

EPA (2003), Air Trends: Pa rticulate Matter, www.epa.gov/ airtrends/pm.html, accessed

Feb. 2003.

FAO (2001), Global Estimates of Gaseous Emissions of NH 3 , NO, and N 2 0 from Agricultural Land, International Fertilizer Industry Association, Food and Agricultural Organization of the United Na tions, Rome, 2001, ISBN 92-5-104698-1.

Finlyason-Pitts, B.J. and J.N. Pitts, Jr. (2000), Chemistry of the Upper and Lower Atmosphere: Theory, Experiments, and Applications , Academic Press, San Diego, CA, pp 583.

IDT, Idaho Transportation Department ( 2006), Idaho Vehicle C ount and Registration Revenue: Calendar Year 2004, itd.idaho.gov/econ/VehicleRegistration/REG04.htm (accessed Jan. 2006).

Klausmeier, R and P. McClintock (2003), Vi rginia Remote Sensing Device Study - Final Report, ESP, Tucson, AZ.

Lefohn A.S., Oltmans S.J. , Dann T. , and Si ngh H.B. (2001), Present-day variability of background ozone in the lower troposphere. J. Geophys. Res ., 106 (D9):9945-9958.

Mangelson, N.F., L. Lewis, J.M. Joseph, W. Cu i, J. Machir, D.J. Eatough, L.B. Rees, T. Wilkerson, and D.T. Jensen, (1997), The c ontribution of sulfate and nitrate to atmospheric fine particles during winter inversion fogs in Cache Valley, Utah. J. Air Waste Manag. Assoc ., 47:167-175.

Martin, R.S. and D. Zhu (2004), Gas- and Part iculate-Phase Ammonia in Northern Utah’s Cache Valley, No.72, presented at the Joint Regional Mee ting of the Northwest and Rocky Mountain Sections of the American Chemical Society, Logan, UT, June 6-9,

2004.

Masters, Gilbert M. (1998), Introduction to Environmental Engineering and Science,

Second Edition , Prentice-Hall, Inc.: U pper Saddle River, NJ: 651.

McCulloch, R.B., G.S. Few, G.C. Murray, and V.P. Aneja, (1998), Analysis of ammonia, ammonium aerosols, and acid gases in the atmosphere at a commercial hog farm in eastern North Carolina, USA, Environ. Pollut ., 102:263-268.

Mount, G.H., B. Rumburg, J. Havig, B. Lam b, H. Westberg, D. Yonge, K. Johnson, and R. Kincaid (2002.), The measurement of atmospheric ammonia at a dairy using differential optical absorption spect roscopy in the mid-ultraviolet, Atmos. Environ

. 36:1799-1810.80 Pryor, S.C., R.J. Barthelmie, L.L. So rensen, and B. Jenson (2001), Ammonia

concentrations and fluxes over a forest in the midwest USA, Atmos. Environ ., 35:5645-

5656.

Robarge, W., J. Walker, G. Murray, and W. Cure (2000), Ambient Concentrations of

Ammonia in Eastern North Ca rolina, presented at the EPA Great Waters Program Workshop: Airsheds and Watersheds: The Significance of Ammonia to Coastal & Estuarine Areas, Nov. 15-16, 2000, Dewey Beach, Delaware.

Sawant, A.A., K. Na, X. Zhu, K. Cocker, S. Butt, C. Song, D.R. Cocker III (2004),

Characterization of PM 2.5 and selected compounds at multip le indoor and outdoor sites in Mira Loma, California, Atmos. Environ. , 38: 6269-6278.

Seinfeld, J.H. and S.N. Pandis (1998), Atmo spheric Chemistry and Physics: From Air Pollution to Climate Change , John Wiley & Sons, Inc. New York, New York, 1326.

Sonoran Insitute (2006), Population, Empl oyment, Earnings, and Personal Income Trends: Franklin County, Idaho, Sonoran Institute, Bozeman, MT, www.sonoran.org/programs/data/IDFranklin.pdf (accessed Jan. 2006).

TECO (2004), ThermoEnvironmental Inst ruments, Model 17C Chemiluminescent Ammonia Analyzer, Operations Manual.

TECO (2006), ThermoEnvironmental Instruments, website, thermo.com/com/CDA/Category/ All_Sub_Child_Category/0,2211,15,00.html , accessed April 2006.

Thoni, L., E. Seitler, A. Blatter, and A. Neftel (2003), A passive sampling method to determine ammonia in ambient air, J. Environ. Monit., 5(1), 96-99.

UGOPB (2006), Utah’s 2006 Economic Report to the Governor, Governor’s Office of Planning and Budget, www.governor.state.ut.us/dea/ERG/ERG2003/ERG2003. pdf (accessed Jan. 2006).

URG (2000), Model 3000C/3000CA Operati on Manual, URG, Chapel Hill, NC.

Utah Division of Air Quality (2006), personal communication.

Watson, J.G., J.C. Chow, F.W. Lurmann, a nd S.P. Musarra (1994), Ammonium nitrate, nitrate acid, and ammonium equilibrium in wintertime Phoenix, Arizona, J . Air Waste Manag, Assoc ., 44:405-412.

Whiteman, C. D., J. M. Hubbe, and W. J. Shaw (2000), Evaluation of an inexpensive temperature datalogger for meteorological applications, Journal of Atmospheric and Oceanic Technology . 17: 77-81.81 Woods Hole Oceanographic Institution (2006), Ozone Measurements in the Marine Boundary Layer from Ocean Buoys, http://www.whoi.edu/MCG/facilities/hint sa_ozone/background.html, accessed May 2006.

Yoong, M. (1981), Measurement of ambient ammonia concentrations in Southern California, Final Report, prepared for the California Air Resources Board, Contract A7- 188-30, Rockwell Internationl, Newberry Park, CA.

Zhu, Dongzi (2005), Analysis of Wintertime Gas- and Particulate-Phase Ammonia in

Assocation with PM2.5 Formation in Cache Vall ey, M.S. Thesis, Utah State University, Logan, UT, June 2005.