THE ENVIRONMENTAL TECHNOLOGY VERIFICATION
PROGRAM
EPA
Baiteiie
The Business of Innovation
TECHNOLOGY TYPE: OZONE INDICATOR CARDS
APPLICATION:
PERSONAL MONITORING OF EXPOSURE TO
OZONE IN AIR
TECHNOLOGY NAME: Ozone Detector Card
COMPANY:
ADDRESS:
WEB SITE:
E-MAIL:
EnviroScan Inc.
689 Unionville Road
Kennett Square, PA 19348
http://enviroscan.net
dieter.feldberg@enviroscan.net
PHONE: 610.925.5101
ETV Joint Verification Statement
The U.S. Environmental Protection Agency (EPA) has established the Environmental Technology Verification
(ETV) Program to facilitate the deployment of innovative or improved environmental technologies through
performance verification and dissemination of information. The goal of the ETV Program is to further
environmental protection by accelerating the acceptance and use of improved and cost-effective technologies.
ETV seeks to achieve this goal by providing high-quality, peer-reviewed data on technology performance to
those involved in the design, distribution, financing, permitting, purchase, and use of environmental
technologies. Information and ETV documents are available at www.epa.gov/etv.
ETV works in partnership with recognized standards and testing organizations, with stakeholder groups
(consisting of buyers, vendor organizations, and permitters), and with individual technology developers. The
program evaluates the performance of innovative technologies by developing test plans that are responsive to
the needs of stakeholders, conducting field and laboratory tests (as appropriate), collecting and analyzing data,
and preparing peer-reviewed reports. All evaluations are conducted in accordance with rigorous quality
assurance (QA) protocols to ensure that data of known and adequate quality are generated and that the results
are defensible.
The Advanced Monitoring Systems (AMS) Center, one of six verification centers under ETV, is operated by
Battelle in cooperation with EPA's National Risk Management Research Laboratory. The AMS Center
evaluated the performance of a colorimetric indicator card for estimating the concentration of ozone in the air.
This verification statement provides a summary of the test results for the EnviroScan, Inc. Ozone Detector Card.
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VERIFICATION TEST DESCRIPTION
This verification test evaluated the ability of the EnviroScan, Inc. Ozone Detector Card to provide reliable
qualitative indications of ozone in air. Laboratory testing was conducted by delivering ozone at known
concentrations in a flowing air stream to Ozone Detector Cards placed in a test apparatus. The delivered ozone
concentrations ranged from zero to approximately 200 parts per billion by volume (ppbv), and were confirmed by
measurements with a continuous monitor designated by EPA as a Federal Equivalent Method (FEM) for ozone.
Visual readings of Ozone Detector Cards exposed in the laboratory testing were made by two non-technical
Battelle staff members who had no knowledge of the ozone test concentrations. Laboratory testing also included
exposure of Ozone Detector Cards to a fixed ozone concentration under lighting conditions ranging from
darkness, to normal laboratory lighting, to simulated full overhead solar spectrum and intensity.
Field testing was conducted by providing Ozone Detector Cards to personnel of the California South Coast Air
Quality Management District (SCAQMD) and to volunteers associated with Breathe California of Los Angeles
(BCLA). SCAQMD personnel exposed and visually read Ozone Detector Cards at field sites where ozone was
being routinely monitored by FEM instruments for compliance purposes. Ambient temperature, relative humidity
(RH), and wind speed were also recorded at the SCAQMD sites. BCLA volunteers exposed and visually read
Ozone Detector Cards at local sites such as schools and parks. Both SCAQMD personnel and BCLA volunteers
provided comments on the use of the cards under field conditions.
The EnviroScan Inc. Ozone Detector Card was verified by evaluating the following performance parameters:
Accuracy - User readings taken with Ozone Detector Cards in laboratory and field testing were compared to
simultaneous ozone measurements made with an EPA FEM ozone monitor. Each comparison in which the
FEM ozone reading fell within the Ozone Detector Card range reported by the card user was deemed an
accurate response.
Variability - Ozone Detector Card readings obtained with constant ozone concentrations in laboratory testing
were used to assess the variability of the card response. Variability was quantified in terms of the number of
different Ozone Detector Card ranges reported by card users when sampling a constant concentration of
ozone.
Duplication - The degree of duplication or consistency of Ozone Detector Card readings was assessed in
three ways, using data from both the laboratory and field testing. Intra-card duplication was assessed using
all readings in which multiple reagent spots on the same card were exposed simultaneously and then read by a
single card user. Inter-card duplication was assessed using all readings in which multiple reagent spots on
different cards were exposed simultaneously and then read by a single card user. User agreement was
assessed using all data in which visual reading of the same exposed reagent spot was made by more than one
user.
Effect of Light Intensity - The effect of light intensity on reagent color development during exposure to
ozone was assessed by laboratory testing at a constant ozone concentration, under three lighting conditions
ranging from darkness to full sun intensity. The impact of light intensity on the accuracy, variability, and
duplication of Ozone Detector Card readings was evaluated.
Effect of Ambient Conditions - Ozone Detector Card readings obtained in field testing were segregated into
accurate and inaccurate readings (i.e., agreeing/disagreeing with coincident FEM measurements). Ambient
temperature, RH, and wind speed data for these two data sets were then statistically compared to investigate
whether field conditions of accurate card readings differed significantly from those of inaccurate readings.
Operational Factors - This performance parameter included factors such as the ease of use of the Ozone
Detector Cards, the readability of the reagent color change in different lighting conditions, and the stability of
the reagent spots during storage before use. Such factors were evaluated based on comments provided by the
users of the cards in field and laboratory testing. Cost was also evaluated based on vendor pricing.
QA oversight of verification testing was provided by Battelle and EPA. Battelle QA staff conducted a technical
systems audit of the laboratory testing, and SCAQMD QA staff conducted a technical systems audit of the field
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testing, under direction of Battelle QA staff. Battelle QA staff also conducted a data quality audit of the test data.
This verification statement, the full report on which it is based, and the test/QA plan for this verification test are
available at www.epa.gov/etv/centers/centerl.html.
TECHNOLOGY DESCRIPTION
The following is a description of the EnviroScan Inc. Ozone Detector Card, based on information provided by the
vendor.
The Ozone Detector Card is approximately 8 cm x 11 cm (3.25 x 4.25 in) in size. Each card has a row of five
spots of solid reagent, with each spot covered by a protective strip of foil. When a foil strip is removed to expose
a reagent spot to air, the reagent reacts with ozone in the air to produce a color change in the spot proportional to
the ozone concentration. An ozone measurement is conducted by removing the foil from a spot and placing the
card in the atmosphere to be tested for 10 minutes. At the end of the 10 minute exposure, the card is folded onto
itself and the user visually compares the color of the exposed reagent spot to a reference color wheel printed on
the front of the Ozone Detector Card. The color wheel has four gradations corresponding to four different ranges
of ozone concentrations:
• Range 1 (10 to 45 parts per billion by volume (ppbv) ozone) corresponds to conditions of little to no ozone
pollution,
• Range 2 (45 to 75 ppbv ozone) corresponds to normal ozone pollution on sunny days,
• Range 3 (75 to 105 ppbv ozone) corresponds to potentially unhealthy conditions,
• Range 4 (>105 ppbv ozone) corresponds to unhealthy conditions.
With a 10-minute exposure period, the degree of reagent color change increases progressively from little to no
change for Range 1 to significant darkening of the reagent spot for Range 4.
VERIFICATION RESULTS
Table VS-1 summarizes the performance results found for the EnviroScan Inc. Ozone Detector Card. Where
data permit, Table VS-1 shows the Ozone Detector Card performance broken down according to the card
range reading that would have been expected based on the actual ozone concentration present.
The table shows that in both laboratory and field testing the Ozone Detector Cards exhibited lower accuracy
and duplication of readings at ozone concentrations corresponding to the highest range reading of the cards
(i.e., range 4). In laboratory testing the accuracy, variability, and duplication of the Ozone Detector Cards
were sometimes worse when exposed to an ozone concentration near the boundary of a detection range than
when exposed to a concentration near the middle of a range, but this effect was not consistently observed.
The Ozone Detector Cards are relatively inexpensive (approximately $1.60 or less per card, when purchased
in lots of 100 or more). Users reported the cards were easy to use, but users had difficulty in matching the
color developed in the reagent spots with the color index printed on the cards. This difficulty may have
contributed to the observed variability of card readings (e.g., in laboratory testing the reported card readings
fell into three different card ranges regardless of the expected range reading). Bright simulated sunlight
during laboratory ozone exposure, and temperature, RH, and wind speed during field use had little effect on
Ozone Detector Card accuracy, but users reported that the lighting conditions under which exposed reagent
spots were read could affect their reported readings.
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Table VS-1. Performance Summary for EnviroScan Ozone Detector Cards
Performance
Parameter
Accuracy (%)a
Variability
(number of card
ranges)3
Intra-Card
Duplication (%)a
Inter-Card
Duplication (%)a
User Agreement
(%)•
Effect of Light
Intensity on Color
Development
during Ozone
Exposure
Effect of Ambient
Conditions on
Accuracy
Operational
Factors
Testing Effort
Laboratory
Range" 1: 96
2: 64
3: 7.8
4: 3.1
Range 1: 3
2: 3
3: 3
4: 3
Range 1: 94
2: 84
3: 94
4: 77
Range 1: 92
2: 59
3: 85
4: 47
Range 1: 91
2: 53
3: 81
4: 55
No effect on accuracy,
variability, or user
agreement; reduced
intra-and inter-card
duplication with full
sun condition
NA
Easy to use; Difficult
to match reagent spot
color to color wheel;
Presence of cards
reduces ozone in test
chamber; Development
of color in reagent
spots during storage of
cards
SCAQMD Field
Range 1: 17
2: 98
3: 65
4: 10
NA
Range 1: 100
2: 100
3: 97
4: 60
100d
NA
NA
Full data set suggests
higher accuracy with
higher temperature and
lower RH; breakdown
by expected range
shows no conclusive
effects.
Easy to use; Difficult
to match reagent spot
color to color wheel;
Visual reading depends
on ambient lighting
conditions; Develop-
ment of color in
reagent spots during
storage of cards
BCLA Field
NAC
NA
NA
NA
100e
NA
NA
Easy to use; Difficult
to match reagent spot
color to color wheel;
Development of color
in one reagent spot
during storage of cards
a: Performance shown for expected ranges of card readings, when information is
b: Range 1 = 10 to 45 ppbv; Range 2 = 45 to 75 ppbv; Range 3 = 75 to 105 ppbv
c: NA = not applicable, no data on this parameter collected from this effort.
d: Based on 23 total cases (insufficient data for breakdown by expected range).
e: Based on 10 total cases.
available.
, Range 4 = >105 ppbv.
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Signed by Tracy Stenner May 16. 2011 Signed by Sally Gutierrez May 20. 2011
Tracy Stenner Date Sally Gutierrez Date
Manager Director
Environmental Solutions Product Line National Risk Management Research Laboratory
Energy, Environment, and Materials Sciences Office of Research and Development
Battelle U.S. Environmental Protection Agency
NOTICE: ETV verifications are based on an evaluation of technology performance under specific,
predetermined criteria and the appropriate quality assurance procedures. EPA and Battelle make no
expressed or implied warranties as to the performance of the technology and do not certify that a technology
will always operate as verified. The end user is solely responsible for complying with any and all applicable
federal, state, and local requirements. Mention of commercial product names does not imply endorsement.
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