United States                  EPA-600 /R-93-177
            Environmental Protection
            Aa<">cy                     September 1993
4>EFA     Research and
            Development
            CONTRIBUTION TO

            INDOOR OZONE LEVELS

            OF AN OZONE GENERATOR
            Prepared for
           Office of Air and Radiation
           Prepared by
           Air and Energy Engineering Research
           Laboratory
           Research Triangle Park NC 27711

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                                  EPA-600/R-93-177
                                  September 1993
                 CONTRIBUTION
            TO INDOOR OZONE LEVELS
             OF AN  OZONE GENERATOR
                 Final Report
                      by

              Raymond S. Steiber
     U.S. Environmental Protection Agency
Air and Energy Engineering Research Laboratory
 Research Triangle Park, North Carolina 27711
                 Prepared for:

     U.S. Environmental Protection Agency
      Office of Research and Development
            Washington, D.C. 20460

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                       EPA REVIEW NOTICE
This report has been reviewed by the U.S. Environmental Protection Agency, and
approved for publication. Approval does not signify that the contents necessarily
reflect the views and policy of the Agency, nor does mention of trade names or
commercial products constitute endorsement or recommendation for use.

This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.

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                            ABSTRACT

Ozone generators are claimed to provide a way to clean indoor air.
The amount of ozone generated  by these devices is a major concern.
A  study  of a  commonly  used  commercially available  unit  was
undertaken to determine the  impact of the ozone generator on indoor
ozone levels. Experiments were conducted in a typical mechanically
ventilated office and in  a test house.  The  ozone generated by the
unit  and  the in-room  ozone concentrations were  measured.   The
results  showed   that,   when   the  unit  was   operated   at  the
manufacturer's  recommended  setting, it generated little  if  any
ozone.  The  indoor  concentrations  in   this   case  were  not
significantly above natural  background.    When  operated  at  the
maximum setting the generator produced large amounts of ozone. In
this situation the indoor ozone concentration exceeded 100 ppb in
well  ventilated spaces  and nearly  1  ppm  in  poorly  ventilated
spaces. When the  ozone  generator was turned  off,  ozone  levels
quickly returned  to background.   No measurements were made to
determine the effect of the device on other aspects of indoor air
guality, such as the elimination  of volatile organic compounds.

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                             CONTENTS

                                                       Page
Abstract                                                 ii

Tables                                                  iii

Metric Conversions                                       iv

Introduction                                              1

Test Group 1                                              2

Test Group 2                                              3

Test Group 3                                              4

Conclusions                                               5

References                                                 6

Appendix.  Quality Evaluation Report                           7
                              TABLES

1     Test Conditions  (Test Group  2)                      3

2     Test Conditions  (Test Group  3)                      4

3     Ozone Generator: Settings  vs Ozone Output          6
                               111

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                   METRIC CONVERSIONS

    Nonmetric units are used in this report for the reader's convenience.
Readers more familiar with the metric system may use the following
factors to convert to those units.
          Nonmetric         Multiplied by        Yields Metric
              ft                 0.3048                 m
              ft2                0.0929                 m2
              in.                2.54                   cm
                                  IV

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INTRODUCTION

     Ozone generators  are claimed to help purify  indoor air and
remove odors  and  other pollutants.   Large industrial scale ozone
generators have been found useful in ameliorating unpleasant odors,
particularly in fire-damaged buildings.   Ozone generators are also
claimed to be  effective in  combatting molds  and bacteria.   There
are no published data  supporting these claims.

     Although manufacturers  of  ozone generators claim that their
units  do not  increase  indoor  levels  of ozone,  they  offer  no
supporting data other than testimonials.  This study was undertaken
to determine the impact of a commercial ozone generator on indoor
ozone levels under typical conditions.  No measurements were made
to determine the effect of  the  device on other aspects of indoor
air quality,  such  as  the elimination of volatile  organic compounds.

     The unit selected for test was an ozone generator designed for
use in the home or  office.   It  has two  user-adjustable controls:
one that varies the  speed of the circulating fan and another that
controls the output  of the ozone.

      The unit was tested under three different  sets of conditions.
Test Group 1 was a 24-hour test under normal operating conditions
in a well-ventilated room. Test Group 2  also  took place in a well-
ventilated room,  but this time  only the higher  ozone generator
settings  were used.    Test  Group  3  was conducted  in  a  poorly
ventilated room.  Here the emphasis was  on what happened when the
ozone generator was  left running overnight with  no air circulation
but normal  leakage   around  the  door and  through  the walls.   In
running these tests,  our chief interest was in the amount of ozone
being contributed to room air and not the  ozone  levels at the face
of the instrument.   However,  these  were  also measured (see Table
3).

     At this point it  might  be well  to  insert  a few words on how
room background  levels  were determined.    Obviously  background
levels could not be  measured when a  test was in progress,  yet at
the same time results could be seriously affected by this number,
particularly at the  lowest concentrations.  In any indoor setting
where there are no  secondary sources of  ozone,  such as  actually
operating copiers, the  chief source  of  ozone will  be outside air
brought into  the  building through natural leakage  or mechanical
ventilation.   Weschler et al.1 have observed that there is roughly
a 2:1 correlation  between outdoor and indoor or.one levels: that is
to say,  if there is a 50 ppb  concentration of ozone outside, indoor
concentrations will  measure  around 25 ppb.  Insofar as these tests
are concerned,  this is  important not  so much  in  terms of  the
numbers themselves  as  it is in the  manner  in which  indoor  air
rigorously tracks outdoor air.   Although the  absolute
                                1

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concentrations may vary from day to day, the rise and fall of ozone
levels over  the course of  a day,  given warm,  sunny weather,  is
absolutely predictable.  In the early morning (before 8 am) ozone
concentrations  will  hover  between  0  and  2-3 ppb.   As  the day
progresses, the levels will gradually rise, reaching their zenith
sometime between noon and 1:30 pm.  On cloudy days the ozone levels
will remain at 0-2 ppb.

     Now how  does this relate  to determining  background indoor
ozone levels?  If a background reading of 2 ppb is measured before
a test begins,  and another background reading of 20 ppb is measured
after it ends,  then a straight line  increase from 2  to 20 ppb over
the course of the test can be inferred  and subtracted sequentially
as background.  On the other hand, if the pre-test reading in the
afternoon is 40 ppb and the  after-test  reading several hours later
is  still  40  ppb, then  it   can  be  assumed  that no significant
excursions have occurred.   Imperfect as this system of background
correction may seem,  it produces surprisingly consistent results,
particularly when checked  against a standard ozone generator, such
as  the  TECO Model 565 ozone generator,  the instrument  used  to
calibrate EPA's  air  network  ozone  detectors.    As  an additional
hedge  against  background  excursions,  many  readings were  taken
during these  tests,  instead of  only a few, so  that the overall
trend could be observed.

TEST GROUP I

      Test Group  1 was run  in a mechanically ventilated  office
with continuously operating air  ducts in the ceiling.   The room
area was  approximately 200   square  feet*  and there  was  a sealed
window at one end and  a hallway  door at  the other.   The unit was
placed on top of a 5-foot high filing cabinet located 3 feet from
the hallway wall.   It was turned at a slight angle in order to give
coverage to the entire room.  As in all these tests, measurements
were made with a Model 560  Thermo-Environmental Ozone Analyzer.
This instrument had  recently been calibrated by personnel of the
Research Triangle Institute,  located  in Research  Triangle Park,
North Carolina (see Appendix for details).   The Model 560 was
placed on top of a 3-foot high table 6 feet 10 inches from the
ozone generator.  Background ozone levels in the room
ranged from  a  few parts per billion  (ppb)  in the  early morning
hours to  over  40 ppb  by  mid-afternoon.   By  far  the  greatest
contributor to these background levels was the effect of sunlight
on atmospheric oxygen. When  it was cloudy during  any  of the tests,
background ozone levels fell, when it was sunny they  rose, and when
it was sunny with visible air pollution they rose dramatically.

      Test Group 1 consisted  of two experiments:  one  that lasted 29
*Readers  more  comfortable  with the  metric system  may use  the
factors listed on page iv to convert to those units.
                                2

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straight hours, during which the ozone generator unit ran
continuously, and a second in which the ozone generator unit was
shut  off.  For  the  first  experiment  both the  fan knob  and the
generator knob were moved to the medium setting (12  o'clock).  This
is slightly above the manufacturer's recommended setting for normal
use (11 o'clock).  The ozone  concentration 14  inches from the face
of the unit is a continuous 5 ppb with the dial  set at 12 o'clock.
Measurements  were  taken  every 30-40  minutes except during the
nighttime hours when no one was present and the room was secured.
At no time during the 29-hour test did the  ozone  levels contributed
to room  air  by the ozone generator rise  to  the point where they
could  be distinguished from  the  background; nor  did  room ozone
levels fall when the unit was shut off for the second test.

TEST GROUP 2

      This   group   of   experiments  was   also   conducted  in  a
mechanically ventilated office with the same configuration and area
as the office used in Test Group 1.  The test conditions for this
group  of tests were the  same  as  for the  first  except  that much
higher settings were used on the ozone generator.   Four separate
tests were run under the conditions listed in Table 1.
          TABLE 1.  Test Conditions (Test Group 2)
TEST #
1
2
3
4
TIME
(hr)
2.0
22.5
24.0
43.0
FAN SETTING
(o'clock)
1
3
5*
Off
GENERATOR SETTING
(o'clock)
1
3
5*
Off
  *Maximum setting
The average concentration of ozone contributed to room air during
Test  1  was  12.2 ppb  and  during  Test  2  was   13.3  ppb.    The
slightness of the difference in readings between Tests 1 and 2 is
probably  indicative  of  the difficulty of  taking  measurements at
such  low  concentrations  vis-a-vis  the  background  and  the  non-
linearity of the controls  on the ozone  generator.   During Test 3
ozone readings were much higher, averaging  100 ppb.  All the above
averages have been corrected for the background.

      Test 4  was an  attempt  to track  room background  across a
number  of different meteorological  conditions.  Concentrations
during the period of its run ranged between 10 and 22 ppb.
                                3

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TEST GROUP 3

      Test Group  3  was  a repetition (with some modifications) of
all the previous  tests,  only in a closed room without mechanical
ventilation.   This room  had an area  of  90 square  feet  and was
roughly the same size as a small bedroom.   It had a single door at
one end and  a closed window at  the  other.   The background ozone
averaged 5.6 ppb in the daytime  and 1.5 ppb in the early morning.
A total of six tests were run.   The conditions are given in Table
2.
           TABLE 2.  Test Conditions (Test Group 3)
TEST #
1
2
3
4
5
6
TIME
(hr)
1.0
0.5
1.0
1.5
22.5
1.0
FAN SETTING
(o'clock)
12
5*
3
5*
5*
Off
GENERATOR SETTING
(o ' clock)
12
12
3
3
5*
Off
*Maximum setting
During Tests  1  and 2 no  concentrations  of  ozone distinguishable
from the background were detected in the room.  During Test  3 an
average of 20.1  ppb was detected.  When the fan speed was increased
during Test 4,   ozone concentrations  more  than  doubled  for  an
average of 43.1  ppb.  During Test 5 both fan and generator settings
were at their maximum.  Of all  the tests that were conducted, this
was the  only  one in which room concentrations  outran the amount
being produced  by  the ozone generator; that  is,  ozone was being
produced  at a  rate  higher than  it could  either be  reacted  or
dispersed by passive air flow.   Starting at an initial
concentration of 150 ppb  during the  first  few  minutes  of the test,
ozone levels rose  to a high of 814  ppb,  then  leveled off between
600 and 700 ppb.   As  the level of these concentrations seemed to
vary according to the frequency with which the door was opened, it
was decided to  let the unit run overnight with  the door secured.
By 7  o'clock  the  next morning room concentrations had  risen to
996.5 ppb.  At  those  levels it was  decidedly  unpleasant for test
personnel  to  enter  the  room, and eye,  throat,  and  olfactory
irritation  reached the  point   where it was nearly  impossible  to
breathe.
      The last test was an attempt to see how quickly high levels

                                4

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of ozone would dissipate from a closed room when their source was
eliminated.  At the beginning of the test the ozone concentration
was 758.5 ppb.  Within an hour it had dropped to 2.0 ppb with most
of the decay occurring in the first  10 minutes.  However, for some
time afterward, a not unpleasant ozone-type odor persisted in the
room.  This odor is best described as similar to that of sheets and
towels when they are  fresh  out  of the  drier,  only much stronger.
Apparently this is not the  odor of  the  ozone itself,  but of some
typical reaction product.

     For those  who might be interested, Table 3  lists  the ozone
output in parts per billion for six selected generator settings.
To obtain  these readings,  the intake nozzle of the  analyzer was
held 14 inches from the face of the generator.   The generator fan
was set at medium (12 o'clock on the dial), and all readings were
corrected for the background.
CONCLUSIONS

      When operated at the recommended setting for normal use (dial
set at the 11  o'clock position),  the ozone generator contributes
little or no ozone  to the background air  levels.   At the highest
setting,  however, it can contribute as much as 100 ppb to a well-
ventilated room and 10 times that  much to a poorly ventilated one.
Our personal experience shows that at that level the air becomes
difficult to breathe and there is some irritation of the eyes and
the mucous membranes, perhaps due to excessive drying.

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                    TABLE 3.   Ozone Generator:
                    Settings vs Ozone Output
 SETTING                     CORRECTED READOUT
(o'clock)                     (PPb ozone)

  7                               0.0
  9                               2.0
 11*                              3.0
 12                               5.0
  1                               8.0
  3                              69.0
  5**                           520.0

 *Manufacturer's recommended setting
**Maximum setting
References;

1. Weschler, C.J., Shields, H.C., Naik, D.V. (1989), "Indoor Air
   Exposures", APCA Journal 39:1562

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                            APPENDIX:

                    QUALITY EVALUATION REPORT

     This study was designed to assess qualitatively the amount of
ozone generated by a commercially available product  claimed by its
manufacturer  to purify  indoor  air  and  remove  odors  and other
pollutants.   Since  validated  test procedures and comparable data
were  unavailable,  planning  for  the  study was   restricted  to
designing  the test system and  considering  fundamental research
needs,  and  a  quality  assurance  plan  was  not prepared.    In
accordance  with  EPA's  quality policy,  data  reported  in  this
document  cannot  be   defended  and   should  be  considered  for
qualitative purposes only.

     However,  quality control  practices,  such  as  routine  good
laboratory practices,  were applied.   A  specific example  was the
calibration of the Model 560 Ozone Analyzer.

     On April 11 and 12,  1990, the Model 560 Ozone Analyzer  (Serial
No.  666864)  was  calibrated   against  an  ozone  photometer  in
accordance with  40  CFR,  Part  50,  Appendix D.    This was  done by
Robert Murdoch and Richard Shores at the Center  for  Environmental
Quality  Assurance  (CEQA)  at  the Research Triangle Institute,
Research Triangle Park,  North  Carolina,  27709-5929.  The results
were as follows:
  CEQA Calibration
   Concentrations in ppm
        0.030
        0.044
        0.058
        0.073
        0.037
Analyzer Response in
 millivolts (0.1 ppm scale)*

        oToo
        0.30
        0.44
        0.58
        0.72
        0.86
*CEQA Analyzer Response (ppm) = (Voltage) (0.100) - 0.000

The CEQA ozone photometer (Dasibi Model 1003AH, Ser. No, 2629) is
periodically checked against  the EPA/EMSL QAD National Institute of
Standards  and Technology  (formerly Bureau  of  Standards)  NIST-
traceable photometer.

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                       TEST GROUP 1

The room had continuously running mechanical sir ventilation.  It
was approximately 200 square feet in area and had a sealed window
at one end and a door at the other.
Test # 1

Date: April 25-26, 1990       Settings: Fan, 12 o'clock
Weather: Sunny and hot with             Generator, 12 o'clock
visible air pollution and
highs near 90 on the 25th;
hazy overcast till 11 am on
the 26th followed by hot and
sunny.

  TIME            UNCORRECTED READOUT         CORRECTED READOUT
  9:10 am             16 ppb                         *
 10:30 am             16 ppb                         *
 11:30 am             24 ppb                         *
  1:00 pm             38 ppb                         *
  2:3 0 pm             38 ppb                         *
  4:0 0 pm             39 ppb                         *
  8:00 am**            8 ppb                         *
  8:30 am              5 ppb                         *
  9:00 am              2 ppb                         *
  9:40 am              3 ppb                         *
 10:30 am              4 ppb                         *
 11:10 am***          18 ppb                         *
 11:40 am             27 ppb                         *
 12:35 pm             41 ppb                         *
  1:15 pm             35 ppb                         *
  1:55 pm             41 ppb                         *

   *Corrected readout was indistinguishable from background.
  **Unit was left running unattended overnight in secured room.
 ***At this point the sun broke through the haze, thereby
    revealing the true source of the ozone readings.

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Test # 2

Date: April 26, 1990         Settings: Fan off
Weather: Hot, sunny, and                Generator off
polluted.

  TIME            UNCORRECTED READOUT
  2:25 pro              42 ppb
  2:55 pm              42 ppb
  3:25 pm              44 ppb
  3:45 pm              42 ppb
  3:50 pro              Experiment Shut Down

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                            TEST GROUP 2
The room had a continuously running mechanical ventilation system
and was approximately 200 square feet in area.  There was a single
sealed window and a single door.
Test # 1

Date: May 7, 1990          Settings: Fan 1 o'clock
Weather: Sunny and                   Generator 1 o'clock
clear, high around 70

  TIME            UNCORRECTED READOUT        CORRECTED READOUT
  2:00 pm              34 ppb                     11 ppb
  2:35 pm              36 ppb                     13 ppb
  3:08 pm              34 ppb                     11 ppb
  3:40 pm              38 ppb                     15 ppb
  4:05 pm              34 ppb                     11 ppb


Test # 2

Date: May 7-8, 1990        Settings: Fan 3 o'clock
Weather: Sunny and                   Generator 3 o'clock
clear both days with
highs in the 70s

  TIME            UNCORRECTED READOUT         CORRECTED READOUT
  4:10 pm              37 ppb                      14 ppb
  7:25 am*             12 ppb                      12 ppb
  8:05 am              11 ppb                      11 ppb
  8:40 am              32 ppb                      10 ppb
  9:20 am              30 ppb                       8 ppb
 10:00 am              35 ppb                      13 ppb
 10:30 am              32 ppb                      10 ppb
 11:10 am              34 ppb                      12 ppb
 11:40 am              38 ppb                      16 ppb
 12:30 pm              38 ppb                      16 ppb
  2:3 0 pm              46 ppb                      2 4 ppb

*Unattended unit was allowed to run overnight in the secured
 room.
                               10

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Test # 3
Date: May 8-9, 1990
Weather: Sunny and clear
with a high of 75 on the
8th; overcast with a high
of 70 on the 9th.
          Settings: Fan 5 o'clock (max)
                    Generator 5 o'clock  (max)
  TIME
  3:15 pm
  4:08 pm
  7:20 am*
  8:10 am
  8:38 am
 10:20 am
 12:40 pm
  3:00 pm
UNCORRECTED READOUT

     110 ppb
     140 ppb
     100 ppb
     100 ppb
     100 ppb
      98 ppb
     120 ppb
     120 ppb
CORRECTED READOUT

     88 ppb
    118 ppb
    100 ppb
    100 ppb
    100 ppb
     98 ppb
     98 ppb
     98 ppb
*Unattended unit left running overnight in the secured room.
 Room background varied from near zero in the forenoon to 22 ppb
 from 12 o'clock on.
Test # 4

Date: May 9, 10, 11, 1990
Weather: Overcast and 70
on the 9th; rain and 70
on the 10th; sunny and 60
on the llth.
           Settings: Fan off
                     Generator off
  TIME
  3:04 pm
  3:50 pm
  8:30 am
 11:20 am
  8:00 am
  9:10 am
 10:30 am
 10:35 am
UNCORRECTED READOUT

      90 ppb*
      22 ppb
      10 ppb
      22 ppb
      10 ppb
      21 ppb
      21 ppb
      Experiment Shut Down
*The ozone generator unit had just been shut down when this reading
was taken, and it is corrected for background.
                                11

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                         TEST GROUP 3

The room  had no mechanical ventilation  and  was approximately 90
square feet  in area.   It had a closed window and a single door.
Background ozone averaged 5.6 ppb during the principal hours of
daylight and 1.5 ppb in the early morning.


Test # 1

Date: May 21, 1990            Settings: Fan 12 o'clock
Weather: Partially sunny,               Generator 12 o'clock
highs in the 80s

  TIME            UNCORRECTED READOUT         CORRECTED READOUT
  2:10 pm              4.8 ppb                       *
  2:2 0 pm              4.6 ppb                       *
  2:3 0 pm              5.5 ppb                       *
  2:4 0 pm              6.4 ppb                       *
  2:5 0 pm              5.4 ppb                       *
  3:0 0 pm              6.1 ppb                       *

 *Indistinguishable from background


Test # 2

Date: May 21, 1990            Settings: Fan 5 o'clock
Weather: As above.                      Generator 12 o'clock

  TIME            UNCORRECTED READOUT         CORRECTED READOUT
  3:10 pm              5.5 ppb                       *
  3:20 pm              5.5 ppb                       *

*Indistinguishable from background
                                12

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                                                          Data/6
Test # 3

Date: May 21, 1990
Weather: Partially
sunny, high in the 80s
            Settings: Fan 3 o'clock
                      Generator 3 o'clock
  TIME
  3:25 pm
  3:35 pm
  3:45 pro
  3:55 pm
  4:05 pro
  4:17 pro
UNCORRECTED READOUT

     23 ppb
     24 ppb
     27 ppb
     27 ppb
     26 ppb
     27 ppb
CORRECTED READOUT

    17.4 ppb
    18.4 ppb
    21.4 ppb
    21.4 ppb
    20.4 ppb
    21.4 ppb
Test # 4

Date: May 22, 1990
Weather: Windy, rain,
high around 60
            Settings: Fan 5 o'clock
                      Generator 5 o'clock
  TIME
  8:05 am
  8:20 am
  8:35 am
  8:50 am
  9:05 am
  9:15 am
  9:25 am
UNCORRECTED READOUT

     54 ppb
     50 ppb
     34 ppb
     46 ppb
     46 ppb
     42 ppb
     40 ppb
CORRECTED READOUT
    52
    48
    32
    44
    44
    40
    38
, 5 ppb
 5 ppb
. 5 ppb
 5 ppb
 5 ppb
 5 ppb
 5 ppb
                                13

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Test # 5

Date: May 22, 1990            Settings: Fan 5 o'clock
Weather: Windy, rain,                   Generator 5 o'clock
high around 60

  TIME            UNCORRECTED READOUT         CORRECTED READOUT
  9:30 am             160 ppb                    158.5 ppb
  9:40 am             260 ppb                    258.5 ppb
 10:25 am             270 ppb                    268.5 ppb
 10:45 am             360 ppb                    354.4 ppb
 11:15 am             340 ppb                    334.4 ppb
 12:10 pm             600 ppb                    594.4 ppb
  1:45 pm             820 ppb                    814.4 ppb
  2:45 pm             700 ppb                    694.4 ppb
  3:30 pm             680 ppb                    674.4 ppb
  4:15 pm*            620 ppb                    614.4 ppb
  7:10 am             998 ppb                    996.5 ppb
  7:50 am             760 ppb                    758.5 ppb

*At this point the room was secured and no more readings were taken
until  the  next morning.   May  23rd dawned  sunny  and  cool  with
morning temperatures in the low 50s.
Test # 6 (Shutdown/Decay)

Date: May 23, 1990            Settings: Fan off
Weather: Sunny and cool,                Generator off
temp, in low 50s
  TIME            UNCORRECTED READOUT         CORRECTED READOUT
  7:54 am         Ozone Generator Shut Off        758.5 ppb
  7:55 am             540 ppb                     538.5 ppb
  8:02 am              70 ppb                      68.5 ppb
  8:10 am               4 ppb                       4.0 ppb
  8 : 2 0 am               2 ppb                       2 . 0 ppb
  8:4 5 am               2 ppb                       2.0 ppb
  8:50 am             Experiment Shut Down
                               14

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                                 TECHNICAL REPORT DATA
                          (Please read Instructions on the reverse before completing'
 1. REPORT NO.
  EPA-600/R-93-177
                            2.
 4. TITLE AND SUBTITLE
 Contribution to Indoor Ozone Levels of an Ozone
  Generator
                                                        3. Rl
                5. REi ... ~~, _
                 September 1993
                6. PERFORMING ORGANIZATION CODE
 7, AUTHOR(S)

 Raymond S.  Steiber
                8. PERFORMING ORGANIZATION REPORT NO
 9. PERFORMING OROANIZAT1ON NAME AND ADDRESS
                                                        10. PROGRAM ELEMENT NO.
 See Block 12
                11. CONTRACT/GRANT NO.
                 NA (Inhouse)
 12, SPONSORING AGENCY NAME AND ADDRESS
 EPA, Office of Research and Development
 Air and Energy Engineering Research Laboratory
 Research Triangle Park, NC 27711
                                                        13. TYPE OF REPORT AND PERIOD COVERED
                                                        Final; 4/90 - 12/92
                14, SPONSORING AGENCY CODE
                 EPA/600/13
 15. SUPPLEMENTARY NOTES ^EERL project officer is Raymond S. Steiber,  Mail Drop 54, 919 /
 541-2288.
 16. ABSTRACT
              repOrt gives results of a study of a commonly used commercially avail-
 able ozone generator, undertaken to determine its impact on indoor ozone levels.  Ex-
 periments were conducted in a typical mechanically ventilated office and in a test
 house. The generated ozone and the in-room ozone concentrations were measured.
 The results showed that, when the unit was operated at the manufacturer's recom-
 mended setting, it generated little if any ozone.  The indoor concentrations in this
 case were not significantly above natural background. When operated at the meximum
 setting, the generator produced large amounts of ozone: over 100 ppb in well ventila-
 ted spaces, and nearly 1 ppm in poorly ventilated spaces. When the  ozone generator
 was turned off,  ozone levels quickly returned to background.  No measurements
 were made to determine the effect of the device on other aspects of indoor air quality
 such as the elimination of volatile organic compounds.
 7.
                              KEY WORDS AND DOCUMENT ANALYSIS
                 DESCRIPTORS
                                           b.tDENTIFiERS/OPEN ENDED TERMS
                            c.  COSATI Field/Group
 Pollution
 Ozone
   Pollution Control
   Stationary Sources
   Ozone Generators
   Indoor Air Quality
13 B
07B
 3. DISTRIBUTION STATEMENT

 Release to Public
   19. SECURITY CLASS (This Report)
   Unclassified
                            21. NO. OF PAGES
   19
   20. SECURITY CLASS (This page)
   Unclassified
                            22. PRICE
EPA Form 2220-i (9-73)
15

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