U.S. Environmental Protection Agency
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ET
ibient Ammonia Monitors
The U.S. EPA Environmental Technology Verification
(ETV) Program's Advanced Monitoring Systems
(AMS) Center, operated by Battelle under a
cooperative agreement with EPA, has verified the
performance of seven ambient ammonia monitors1 for
use at animal feeding operations (AFOs). The current
standard method for measuring ambient ammonia is
time consuming, labor intensive, and not well-suited for
conducting continuous measurements. The verified
monitors can provide a quick and convenient way of
measuring ammonia. These monitors were verified in
collaboration with the U.S. Department of Agriculture
(USDA).
Technology Description and
Verification Testing
The AMS Center verified the seven ambient ammonia
monitors (Table 1) in two phases of testing, each at
separate AFOs. Phase I was conducted at a swine
finishing farm, and Phase II was conducted at a cattle
feedlot. These sites were selected to provide realistic
testing conditions and a wide range of ammonia concen-
trations. Table 2 summarizes some of the performance
data for the individual technologies. The full verification
reports can be found at http://www.epa.gov/nmirl/std/
etv/vt-ams.html under ambient ammonia sensors cate-
gory. Ambient ammonia monitors utilize a wide range of
analytical methods. These methods include direct
detection by spectroscopic techniques or indirect detection
of ammonia using selective membrane permeation with
conductivity detection, catalytic conversion with
chemiluminescence detection, treatment with a chemical
dopant followed by ion mobility detection, or other
techniques. Ambient ammonia monitors also can
provide specialized features that can be valuable in
specific uses, such as long-term
monitoring or determining ammonia
fluxes and emission rates.
AFOs and Ammonia at a Glance
Animal husbandry operations, which include
AFOs, are regarded as representing the largest
single source of ammonia in the United States,
emitting 2,200 thousand metric tons in 2002
alone. Approximately half of the ammonia from
the ponds and lagoons used to manage animal
wastes at AFOs falls to the surface within 50
miles of these sources, where it can contribute to
eutrophication of surface waters and result in fish
kills and reduced biodiversity. The remainder is
transformed into particulate matter, which can
have significant adverse human health effects.
The Clean Air Act; Comprehensive
Environmental Response, Compensation, and
Liability Act; and Emergency Planning and
Community Right-to-Know Act include
requirements for monitoring and reporting
ammonia releases that are applicable to some
AFOs. In 2003, the National Academies of
Science identified the methods used to estimate
ammonia emissions from these sources (i.e., that
apply generic emission factors to estimates of
live stock population) as general!}' inadequate,
and they recommended improvement in
measurement protocols for ammonia. EPA
recently issued an Air Quality Compliance
Agreement (AQCA) with the animal producers
industry to improve ammonia emissions
measurements and promote compliance with
federal regulations. Some ETV-verified
technologies utilize the analytical methods
identified in the AQCA study protocol.
For example, monitors that collect
high-speed (sub-second response
time) ammonia concentration data
can be used with simultaneous
three-dimensional windspeed/
direction data to determine
ammonia flux. Alternatively, open-
path monitors can be used to
calculate emission rates from AFOs,
since these monitors measure
the average ammonia concentration
over a 1-to-100 meter path. Some
monitors also are suitable for long-
term monitoring, since they can be
operated without user intervention
for weeks at a time.
Table 1. Verified Ambient Ammonia Monitors
Technology Name
Aerodyne Research, Inc.
QC-TILDAS
Bruker Daltonics OPAG 22 Open-
Path Gas Analyzer
Molecular Analytics lonPro-IMS
Ammonia Analyzer
OmnisensSATGA310
Ammonia Analyzer
Pranalytica, Inc. Nitrolux™ 1000
Ambient Ammonia Analyzer
Mechatronics Instruments BV
AiRRmonia Ammonia Analyzer
Thermo Electron Corp. Model 17C
Ammonia Analyzer
Description
An infrared laser spectrometer, based on pulsed
quantum cascade laser technology; continuous measure-
ment
A broadband, open-path, Fourier transform infrared
spectrometer for remote sensing continuous measurement
An ion mobility spectrometer; continuous measurement
A trace gas analyzer that uses photoacoustic spectrometry;
continuous measurement
A resonant photoacoustic spectrometer with a line-tunable
carbon dioxide (C02) laser; continuous measurement
A single-point monitor composed of a membrane diffusion
sampler, a detector block with a diffusion membrane, and
two conductivity cells; continuous measurement
A chemiluminescence analyzer that uses nitric oxide (NO)
and ozone (03) reactions; time-averaged measurement
The ETV Program operates largely as a public-private partnership through competitive cooperative agreements with non-profit research institutes. The
program provides objective quality-assured data on the performance of commercial-ready technologies. Verification does not imply product approval or
effectiveness. ETV does not endorse the purchase or sale of any products and services mentioned in this document.
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Selected Outcomes of Verified Ambient
Ammonia Monitors
The potential market for verified ambient ammonia monitors
includes AFOs. EPA estimates that there are approximately
450,000 AFOs in the U.S. Larger facilities (more than 1000
animal units ) with higher emissions are more likely to
implement monitoring technologies. The verified monitors
could:
• be used under EPA's Voluntary Air Compliance Agreement
to improve ammonia emission estimates
• help address the research needs identified by the National
Academies of Science and others
An ambient ammonia monitor at an AFO
• be applied potentially at up to 975 large AFOs (out of an
estimated potential market of 3,900) to verify their compliance with current or potential future state and
federal regulations and to avoid potential multimillion dollar penalties
• identify operational changes to improve ammonia control and reduce emissions from AFOs; a 10%
reduction in livestock ammonia emissions can lead to over $4 billion annually in particulate-related health
benefits (McCubbin et al).
2 An animal unit is equal roughly to one beef cow.
Table 2. Selected Performance of Verified Ambient Ammonia Monitors
Vendor8
A
B
C
D
E
F
G
Testing
Phase I
& Phase
II
Phase I
& Phase
II
Phase I
& Phase
II
Phase II
Phase II
Phase II
Phase I
& Phase
II
Average
Relative
Accuracy1"
3.7 to
10.5%
2.4 to 34%
10 to 44%
2.2%
18.3%
26%
4.7 to 10%
Relative
Precision11
0.3%
0.7 to 2.1%
0.2 to 1.3%
0.9%
1.0%
1.8%
1.9 to 2.5%
Response
Time (95%)
3 to 76 min
8 to 20 min
1 to 32 min
2 to 2.6 min
2.5 to 17 min
4 to 14 sec
0.8 to 66 sec
Linearity
Slope
0.90 to
1.03
1.02 to
1.28
0.71 6 to
1.25
0.966
0.815
0.583
0.840 to
0.962
Intercept
-24 to -0.6
-2.4 to 136
-58.5 to 167
15.9
1.08
24.9
-8.8 to 35
r*
1.000
0.9957 to
0.9999
0.9854 to
0.9997
1.000
1.000
0.9144
0.9989 to
0.9998
Comparability0
Slope
0.86 to
1.20
0.41 to
1.18
0.646 to
1.83
1.15
1.565
Not
reported
0.984 to
1.09
Intercept
-0.5 to 16
-1.4 to 58
-6.7 to 21. 6
-4.1
-16.5
Not
reported
-9.5 to 14.4
r*
0.984 to
0.990
0.538 to
0.9755
0.9794 to
0.9842
0.994
0.994
Not
reported
0.9943 to
0.9982
a Because the ETV Program does not compare technologies, the performance results shown in this table do not identify the vendor associated with
each result and are not in the same order as the list of technologies in Table 1 .
b A result of 0% indicates perfect accuracy or precision.
0 The comparability of the verified technology with a standard reference method was established by comparing the average ammonia sensors
readings with time-integrated Nhh samples collected using citric-acid-coated denuders. The reference samples were collected based on procedures
described in the EPA Compendium Method IO-4.2, Determination of Reactive Acidic and Basic Gases and Acidity of Fine Particles (<2.5 urn).
Comparability between the ammonia sensors results and the reference method results with respect to ambient air was assessed by linear
regression using the reference method NH3 concentrations as the independent variable and results from the ammonia sensor as the dependent
variable.
ETV Advanced Monitoring
Systems Center
Robert Fuerst, EPA
fuerst.robert@epa.gov
Tel: (919) 541-2220
Amy Dindal, Battelle
dindala@battelle .org
Tel: (561) 422-0113
References
U.S. EPA, 2006. ETV Case Studies: Demonstrating Program Outcomes.
EPA/600/R-06/001. January. (Primary source)
U.S. EPA, ETV, http://www.epa.gov/etv.
McCubbin, D.R., B.J. Apelberg, S. Roe, and F. Divita Jr. 2002.
"Livestock Ammonia Management and Particulate-Related Health
Benefits." Environ. Sci. Technol. 36:1141-1146.
U.S. EPA Animal Feeding Operations, http://www.epa.gov/oecaagct/
anafoidx.html.
EPA/600/S-07/009
February 2007
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