United States
Environmental Protection
Agency
National Risk Management
Research Laboratory
Cincinnati, OH 45268
Research and Development
EPA/600/SR-95/121 August 1995
&EPA Project Summary
Airborne Asbestos
Concentrations During Buffing,
Burnishing, and Stripping of
Resilient Floor Tile
John R. Kominsky, Ronald W. Freyberg, and James M. Boiano
This study was conducted to evalu-
ate airborne asbestos concentrations
during low-speed spray-buffing, ultra
high-speed burnishing, and wet-strip-
ping of asbestos-containing resilient
floor tile under pre-existing and pre-
pared levels of floor care maintenance.
Airborne asbestos concentrations were
measured before and during each floor-
care procedure to determine the mag-
nitude of the increase in airborne
asbestos levels during each procedure.
Airborne total fiber concentrations were
also measured for comparison with the
Occupational Safety and Health Admin-
istration (OSHA) Permissible Exposure
Limit (PEL) of 0.1 f/cm3, 8-hr, time-
weighted average (TWA). Low-speed
spray-buffing and wet-stripping were
evaluated on pre-existing floor condi-
tions and three levels of prepared floor-
care conditions (poor, medium, and
good). Ultra high-speed burnishing and
wet-stripping were evaluated on two
levels of prepared floor-care conditions
(poor and good). All of the computed
8-hr. TWA personal sample results were
below the OSHA PEL. It is noted that
the floor tile in this study was of low
asbestos content and in good condi-
tion, hence it is conceivable that floor
tile with higher percentages of asbes-
tos could result in higher levels of air-
borne asbestos during routine floor
care maintenance activities. TEM analy-
sis showed higher exposures to fibers
predominantly less than 5 urn in length,
whereas these shorter fibers were not
counted by PCM.
This study shows that low-speed
spray-buffing, ultra high-speed burnish-
ing, and wet-stripping of asbestos-con-
taining resilient floor tile can be sources
of airborne asbestos in building air.
The results suggest that multiple lay-
ers of sealant applied to the floor prior
to the application of the floor finish
can reduce the release of asbestos fi-
bers during polish removal. The results
of this study further support the U.S.
EPA Recommended Interim Guidance
for Maintenance of Asbestos-Contain-
ing Floor Coverings.
This Project Summary was developed
by EPA's National Risk Management
Research Laboratory, Cincinnati, OH,
to announce key findings of the re-
search project that is fully documented
in a separate report of the same title
(see Project Report ordering informa-
tion at back).
Introduction
Three principal types of preventive main-
tenance are routinely performed on resil-
ient floor tile: spray-buffing, ultra
high-speed burnishing, and wet-stripping
followed by refinishing. Spray-buffing is
the restorative maintenance of a previ-
ously polished floor by use of a floor-
polishing machine (operating at 175 to
1000 rpm) immediately after the surface
has been mist-sprayed with a restorative
product whereby the floor is buffed to dry-
ness. Ultra high-speed burnishing is the
buffing of a previously polished floor by
using a floor polishing machine (operating
at greater than 1500 rpm) without using a
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restorative spray product. Wet-stripping is
the removal of the finish from the floor
using a chemical floor-polish stripper and
a 175 rpm floor machine equipped with an
appropriate strip pad. This current study
was conducted to evaluate airborne as-
bestos concentrations during low-speed
spray-buffing, ultra high-speed burnishing,
and wet-stripping of asbestos-containing
resilient floor tile under pre-existing and
prepared levels of floor care maintenance.
Objectives
The objectives of the study were as
follows:
• To determine the airborne asbestos
concentrations during low-speed
spray-buffing of asbestos-containing
resilient floor tile in pre-existing floor
condition.
• To determine airborne asbestos con-
centrations during polish removal from
asbestos-containing resilient floor tile
in pre-existing floor condition.
• To determine and compare the air-
borne asbestos concentrations dur-
ing low-speed spray-buffing of
asbestos-containing resilient floor tile
in poor, medium, and good floor con-
ditions.
• To determine and compare airborne
asbestos concentrations during pol-
ish removal after low-speed spray-
buffing of asbestos-containing resilient
floor tile in medium and good condi-
tions using a manual floor machine.
• To determine and compare the air-
borne asbestos concentrations dur-
ing ultra high-speed burnishing of
asbestos-containing resilient floor tile
in poor and good floor conditions.
• To determine and compare the air-
borne asbestos concentrations dur-
ing polish removal after ultra
high-speed burnishing of asbestos-
containing resilient floor tile in poor
and good floor conditions using an
automated floor machine.
• To determine whether personal
breathing zone concentrations during
low-speed spray-buffing of floors in
pre-existing, poor, medium, and good
conditions exceed the OSHA Permis-
sible Exposure Limit (PEL) of 0.1 f/
cm3, 8-hr. Time-Weighted Average
(TWA).
• To determine whether personal
breathing zone concentrations during
ultra high-speed burnishing of floors
in poor and good conditions exceed
the OSHA PEL of 0.1 f/cm3, 8-hr.
TWA.
• To determine whether personal
breathing zone concentrations during
polish removal after low-speed spray-
buffing of floors in pre-existing, poor,
medium, and good condition exceed
the OSHA PEL of 0.1 f/cm3, 8-hr.
TWA.
• To determine whether personal
breathing zone concentrations during
polish removal after ultra high-speed
burnishing of floors in poor and good
conditions exceed the OSHA PEL of
0.1 f/cm3, 8-hr. TWA.
Site Description
This study was conducted in an unoc-
cupied building located at the decommis-
sioned Chanute Air Force Base (AFB) in
Rantoul, IL. The study was conducted in a
room which contained approximately 8600
ft2 of open floor space tiled with 9-inch by
9-in. resilient floor tile containing approxi-
mately 5% chrysotile asbestos. Represen-
tatives of the Chemical Specialties
Manufacturers Association (CSMA) and a
floor products manufacturer visually in-
spected the physical condition of the floor.
Their inspection focused on the evenness
of the floor plane and the physical condi-
tion of the tile. They concluded that the
floor was acceptable for the proposed
study.
Configuration for Low-speed
Spray-buffing and Wet-
stripping Experiments
Approximately 6500 ft2 of floor space
was isolated as the experimental test area.
A containment shell was constructed from
2-in. by 4-in. and 2-in. by 6-in. lumber to
provide five equally-dimensioned test
rooms, each with approximately 1300 ft2
of floor space and 7-ft ceiling height. The
containment shell was then surfaced with
6-mil polyethylene sheeting to provide air-
tight walls and ceilings for the five test
rooms. The ceiling for each test room
consisted of a single layer of polyethylene
sheeting. The walls of each test room
were surfaced with seven layers of poly-
ethylene sheeting. Four high-efficiency
particulate air (HEPA) filtration units were
placed in the hallway outside of the five
test rooms to ventilate the test rooms and
reduce the airborne asbestos concentra-
tions to background levels after each ex-
periment.
Configuration for Ultra High-
Speed Burnishing and Wet-
Stripping Experiments
Upon completion of the low-speed
spray-buffing and wet-stripping experi-
ments, the test area was reconfigured to
accommodate the ultra high-speed bur-
nishing and wet-stripping experiments. The
test area was reconfigured to provide a
single test room of approximately 6500 ft2
of floor space and 7-ft. ceiling height. The
ceiling for the test room consisted of a
single layer of polyethylene sheeting. The
walls were surfaced with eight layers of
polyethylene sheeting. Three HEPA filtra-
tion units were placed in the hallway out-
side of the test room to ventilate the test
room and reduce the airborne asbestos
concentrations to background levels after
each experiment. The units were oper-
ated during the preparation phase of each
experiment but not during the actual bur-
nishing or wet-stripping experiments. All
three HEPA units discharged the air out-
doors via 12-in. diameter flexible ducting.
Fresh air into the test room was obtained
directly from outdoors through windows.
Experimental Design
Low-Speed Spray-Buffing and
Wet-Stripping
Pre-existing Conditions
Low-speed spray-buffing was first evalu-
ated on the pre-existing floor-care condi-
tion. Pre-existing condition was the
condition of the floor as it existed in the
room prior to evaluating the prepared floor-
care conditions. Pre-existing floor condi-
tions consisted of an undetermined number
of coats of a Carnauba-type, buffable pol-
ish on the floor tile. Low-speed spray-
buffing of the pre-existing floor-care
condition was evaluated five times, once
in each of the five test rooms. Wet-strip-
ping (including polish and sealant removal)
was also evaluated on the pre-existing
floor-care condition. Wet-stripping of the
pre-existing floor-care condition was evalu-
ated five times, once in each of the five
test rooms.
Prepared Floor Care Conditions
Low-speed spray-buffing was evaluated
on three levels of prepared floor-care con-
ditions: 1) poor floor-care condition, 2)
medium floor-care condition, and 3) good
floor-care condition. Poor floor-care con-
dition was defined as a floor with one coat
of sealant and one coat of polish. Medium
floor-care condition was defined as a floor
with one coat of sealant and two coats of
polish. Good floor-care condition was de-
fined as a floor with two coats of sealant
and three coats of polish. Floor-care con-
ditions were defined in consultation with
the CSMA and other representatives of
floor-care products manufacturers. Each
floor-care condition was evaluated five
times, once in each of the five test rooms,
to yield a total of 15 experiments.
Wet-stripping after low-speed spray-buff-
ing was evaluated on two levels of floor-
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care conditions (medium and good). This
comparison addresses the effectiveness
of two coats of sealant versus one coat of
sealant to limit the extent of airborne as-
bestos concentrations during polish re-
moval. Wet-stripping of each of the two
floor-care conditions were evaluated five
times, once in each of the five test rooms,
to yield a total of 10 experiments.
Ultra High-Speed Burnishing
and Wet-Stripping
Ultra high-speed burnishing was evalu-
ated on two levels of prepared floor-care
conditions: 1) poor floor-care condition,
and 2) good floor-care condition. Poor
floor-care condition was defined as a floor
with two coats of sealant and one coat of
polish. Good floor-care condition was de-
fined as a floor with two coats of sealant
and four coats of polish. Floor-care condi-
tions were defined in consultation with the
CSMA and other representatives of floor-
care chemicals manufacturers. Each floor-
care condition was evaluated four times
to yield a total of eight experiments.
Wet-stripping after ultra high-speed bur-
nishing were also evaluated on two levels
of floor-care condition (poor and good).
Each of the two floor-care conditions were
evaluated four times to yield a total of
eight experiments.
The CSMA and other representatives
from the floor-care chemicals industry
specified different definitions of poor and
good floor-care conditions for the low-
speed and ultra high-speed experiments
based on the varying nature of the two
floor-care procedures. Although this pre-
cluded a direct comparison of the results
from the low-speed and ultra high-speed
experiments, the different definitions of
floor-care condition were necessary to con-
duct a practical evaluation of each floor-
care procedure.
Sampling Strategy
Area air samples were collected before
each experiment to establish a baseline
airborne asbestos concentration in the test
room for comparison with the concentra-
tion measured during low-speed spray-
buffing, ultra high-speed burnishing or
wet-stripping. After the baseline samples
were started, the floor of the test room
was thoroughly swept with the exhaust of
a 1-hp leaf blower. Five baseline area air
samples were collected in each test room/
area before each experiment. One sample
was located in each quadrant of the test
room; the fifth sample was located in the
center of the test room. Two field blanks
(one open and one closed) were also col-
lected during the baseline sampling as a
control for filter contamination.
Three personal breathing zone samples
were collected on the equipment operator
during each experiment for comparison
with the baseline samples. Two additional
personal samples were also collected on
the operator for comparison to the OSHA
PEL of 0.1 f/cm3, 8-hr TWA. Three field
blanks (one open and one closed 0.45 urn
mixed cellulose ester (MCE), one open
0.8 urn MCE) were also collected during
each experiment as a control for filter con-
tamination.
Sampling Methods
The area air samples (baseline and out-
door) were collected on open-face, 25-
mm diameter, 0.45-um pore-size, MCE
filters with a 5-um pore-size cellulose sup-
port pad contained in a three-piece cas-
sette. The filter cassettes were positioned
approximately 5 ft above the floor with the
face of the filter at a 45° angle toward the
floor. The filter assembly was attached to
an electric-powered (110 VAC) 1/6-hp
vacuum pump operating at a flowrate of
approximately 9 l/min.
Five personal breathing zone air
samples were collected during each ex-
periment on the individual operating the
floor machine. Two samples were collected
on open-face, 25-mm diameter, 0.8-um
poresize MCE membrane filters and cellu-
lose support pad contained in a three-
piece cassette with a 50-mm conductive
extension cowl. These two samples were
analyzed by phase contrast microscopy
(PCM). Three additional personal breath-
ing zone samples were collected on an
open-faced, 25-mm-diameter, 0.45 urn
pore-size MCE filters with a 5 um pore-
size MCE diffusing filter and a cellulose
support pad contained in a 3-piece cas-
sette. These three samples were analyzed
by transmission electron microscopy
(TEM).
Analytical Methods
Baseline Samples
The MCE filters were prepared and ana-
lyzed in accordance with the nonmandatory
TEM method specified in the AHERA Fi-
nal Rule (October 30, 1987; 52 CFR 4826).
In addition to the requirements of the
AHERA nonmandatory TEM method, the
specific length and width of each structure
were measured and recorded. A sufficient
number of grid openings were analyzed to
ensure a sensitivity (the concentration rep-
resented by the finding of a single struc-
ture) of no greater than 0.005 asbestos
structures per cubic centimeter of air
sampled, unless the degree of loading
made this impractical. On heavily loaded
samples, counting stopped after complet-
ing the grid square in which the 100th
asbestos structure was found.
Personal Breathing Zone
Samples
The two 0.8-um pore-size MCE filters
used to collect the personal breathing zone
samples were analyzed by PCM. These
samples were prepared and analyzed ac-
cording to NIOSH Method 7400 (Revision
3, June 5, 1989, National Institute for Oc-
cupational Safety and Health Manual of
Analytical Methods). The analytical sensi-
tivity was approximately 0.01 fibers/cm3 of
air sampled. The three personal breathing
zone samples collected on 0.45 um
poresize MCE filters were analyzed by
TEM as described above for the baseline
samples.
Statistical Methods
The relative change in airborne asbes-
tos concentration was measured by the
ratio of the average concentration during
the specific maintenance procedure to the
average concentration before the mainte-
nance procedure. These ratios were then
compared by taking the natural logarithm
and comparing the averages by standard
analysis of variance (ANOVA) techniques.
Quality Assurance
During the study, sample chain-of-cus-
tody procedures were an integral part of
both the sampling and analytical activities
and were followed for all air and bulk
samples collected. The field custody pro-
cedures documented each sample from
the time of its collection until its receipt by
the analytical laboratory. Internal labora-
tory records then documented the cus-
tody of the sample through its final
disposition. Specific quality assurance pro-
cedures outlined in the AHERA rule were
used to ensure the precision of the collec-
tion and analysis of air samples, including
filter lot blanks, open and closed field
blanks, and repeated sample analyses.
Results and Discussion
Low-Speed Spray-Buffing and
Wet-Stripping Experiments
Pre-existing Floor Conditions
TEM Concentrations
Low-speed spray-buffing and wet-strip-
ping were first evaluated on the pre-exist-
ing floor-care condition. Pre-existing
condition was the condition of the floor as
it existed in the room prior to evaluating
the prepared floor care conditions.
Results of the one-factor ANOVA indi-
cate that the specific maintenance proce-
-------
dure had a statistically significant effect
on airborne asbestos concentrations mea-
sured during the procedure (p=0.0128).
Specifically, larger increases in airborne
asbestos concentrations were observed
during wet-stripping than during spray-buff-
ing. The estimated airborne asbestos con-
centrations during spray-buffing and
wet-stripping as a proportion of the re-
spective baseline concentrations were cal-
culated along with the corresponding 95%
confidence interval. The average airborne
asbestos concentration measured during
low-speed spray-buffing was approximately
11 times greater than the average baseline
concentration. The 95% confidence inter-
val for this proportion is (2.6, 47). The
lower 95% confidence limit is greater than
1, which indicates this is a statistically
significant increase. The average airborne
asbestos concentration measured during
wet-stripping was approximately 186 times
greater than baseline concentrations. The
95% confidence interval for this propor-
tion is (44, 788). The lower 95% confi-
dence limit is greater than 1, which
indicates this is a statistically significant
increase.
PCM Concentrations
Two personal breathing zone samples
were collected during each experiment and
analyzed by PCM. None of the individual
PCM concentrations exceeded the OSHA
PEL of 0.1 f/cm3. The highest individual
PCM concentration (0.023 f/cm3) was mea-
sured during wet-stripping. The 8-hr TWA
concentrations associated with the mea-
sured levels were calculated by assuming
zero exposure beyond that which was
measured during the experiment. The 8-
hr TWA concentrations ranged from 0.001
to 0.003 f/cm3 during low-speed spray-
buffing and from 0.0003 to 0.003 f/cm3
during wet-stripping of floors in pre-exist-
ing condition. None of the 8-hr TWA con-
centrations exceeded the OSHA PEL of
0.1 f/cm3.
Although the results of the personal
breathing zone samples analyzed by PCM
were all below the OSHA PEL, consider-
ably higher exposures were shown by the
personal breathing zone samples analyzed
by TEM. Two primary reasons explain why
the TEM concentrations were consider-
ably higher than the PCM concentrations.
First, PCM cannot detect fibers thinner
than 0.25 urn in width. Second, the PCM
method used in this study (i.e., NIOSH
7400) does not count fibers shorter than 5
urn in length. Over 99% of the asbestos
structures measured during low-speed
spray-buffing and wet-stripping of floors in
pre-existing condition were shorter than 5
urn in length and would therefore not be
counted by the PCM method.
Caution should be exercised in extrapo-
lating the PCM measurements collected
during this study to conditions at other
sites. These tile were of low asbestos
content and in good condition, and no
other asbestos exposure activity was as-
sumed.
Prepared Floor Conditions
TEM Concentrations
Figure 1 illustrates the overall average
(geometric mean) concentrations mea-
sured before and during low-speed spray-
buffing and wet-stripping on floors in
prepared floor conditions. Although the
mean relative increase in airborne asbes-
tos concentrations during low-speed spray-
buffing tended to decrease as the floor
care condition improved (i.e., poor condi-
tion resulted in a larger relative increase
than medium, and medium condition
showed a larger relative increase than
good), the differences between the three
levels of floor care were not statistically
significant (p=0.1149). Overall, the aver-
age airborne asbestos concentration dur-
ing low-speed spray-buffing was
approximately 2.6 times higher than the
average baseline concentration. This in-
crease was statistically significant
(p=0.0017). A 95% confidence interval for
the mean airborne asbestos concentra-
tion during spray-buffing as a proportion
of the baseline concentration showed that
the overall mean airborne asbestos con-
10
c
o
Of
o
c
o
u
Vi
o
Ul
Of
0=1
I/I
0.1
o
I 0.01
0.001
Sample Period
I Baseline | During
Low-Speed Spray-Buffing
Poor Medium Good Medium
Prepared Floor Care Condition
Good
Figure 1. Average airborne asbestos concentrations during low-speed spraying of floors in prepared conditions.
-------
centration was between 1.3 and 5 times
greater during buffing than before buffing.
Significantly larger increases in airborne
asbestos concentrations were observed
during wet-stripping of floors in medium
condition than on floors in good condition
(p=0.0029). The relative increase in air-
borne asbestos concentrations (i.e., com-
pared to baseline measurements) was
approximately 14 times greater, on aver-
age, during wet-stripping of floors in me-
dium condition than during wet-stripping
of floors in good condition.
The estimated airborne asbestos con-
centrations during wet stripping of floors
in medium and good condition as a pro-
portion of the respective baseline concen-
trations were calculated along with the
corresponding 95% confidence interval.
The average airborne asbestos concen-
tration measured during wet-stripping of
floors in medium condition was approxi-
mately 108 times greater than the aver-
age baseline concentration. The 95%
confidence interval for this proportion is
(33, 335). The lower 95% confidence limit
is greater than 1, which indicates this is a
statistically significant increase. The aver-
age airborne asbestos concentration mea-
sured during wet-stripping of floors in good
condition was approximately 8 times
greater than the average baseline con-
centration. The 95% confidence interval
for this proportion is (2.5, 25). The lower
95% confidence limit for this proportion is
greater than 1, which indicates this is a
statistically significant increase. The strip-
ping solution used on these floors was
designed to remove only the polish from
the floor, leaving the layer(s) of sealant on
the floor. Therefore, although significant
increases in airborne asbestos concentra-
tions were observed during wet-stripping
of floors in both medium and good condi-
tion, the extra layer of sealant on floors in
good condition appears to significantly de-
crease the airborne asbestos levels.
Overall, significantly larger increases
(p=0.0001) in airborne asbestos concen-
trations were observed during wet-strip-
ping than during low-speed spray-buffing
(this comparison was restricted to floors
in medium and good condition since wet-
stripping was not evaluated on floors in
poor condition). The relative increase in
airborne asbestos concentrations was
approximately 18 times greater, on aver-
age, during wet-stripping than during low-
speed spray-buffing.
PCM Concentrations
Two personal breathing zone samples
were collected during each experiment and
analyzed by PCM. None of the individual
PCM concentrations exceeded the OSHA
PEL of 0.1 f/cm3. The highest individual
PCM concentration (0.032 f/cm3) was mea-
sured during low-speed spray-buffing. The
8-hr TWA concentrations associated with
the measured levels were calculated by
assuming zero exposure beyond that
which was measured during the experi-
ment. The 8-hr TWA concentrations
ranged from 0.0003 to 0.006 f/cm3 during
low-speed spray-buffing and from 0.0003
to 0.002 f/cm3 during wet-stripping. None
of the 8-hr TWA concentrations exceeded
the OSHA PEL of 0.1 f/cm3. It is noted,
however, that these tile were of low as-
bestos content and in good condition, and
that no other asbestos exposure activity
was assumed. TEM analysis showed
higher exposures to structures predomi-
nantly less than 5 urn in length. Over 99%
of the asbestos structures measured dur-
ing low-speed spray-buffing and wet-strip-
ping of floors in pre-existing condition were
shorter than 5 urn in length and would not
be counted by the PCM method. There-
fore, caution should be exercised in ex-
trapolating the PCM measurements
collected during this study to conditions at
other sites.
Ultra High-Speed Burnishing
and Wet-Stripping Experiments
TEM Concentrations
Figure 2 illustrates the average airborne
asbestos concentrations measured before
and during high-speed burnishing and
stripping. Results of the two-factor ANOVA
indicate that neither the maintenance pro-
cedure (p=0.2491) nor the floor condition
(p=0.7396) had a statistically significant
effect on the relative increase in airborne
asbestos concentrations measured during
the maintenance procedure. That is, simi-
lar increases in airborne asbestos con-
centrations were seen during ultra
high-speed burnishing and wet-stripping
of floors in both poor and good condition.
No floor condition or maintenance proce-
dure resulted in significantly higher or lower
increases in mean airborne asbestos
concentration.
The estimated airborne asbestos con-
centrations during ultra high-speed bur-
nishing and wet-stripping as proportions
of the respective baseline concentrations
were calculated along with the correspond-
ing 95% confidence interval. When aver-
aged over floor care condition (good, poor),
the mean airborne asbestos concentra-
tion during ultra high-speed burnishing was
approximately 14 times greater than the
mean baseline concentration. The 95%
confidence interval for this proportion is
(7.6, 26). The lower confidence limit is
greater than 1, which indicates this is a
statistically significant increase. Similarly,
when averaged over floor care condition,
the mean airborne asbestos concentra-
tion during wet-stripping was approximately
9 times greater than the mean baseline
concentration. This increase is also statis-
tically significant.
The estimated airborne asbestos con-
centrations during procedures on floors in
poor and in good condition as proportions
of the respective baseline concentrations
were calculated along with the correspond-
ing 95% confidence interval. When aver-
aged over floor care procedure (ultra
high-speed burnishing, wet-stripping), the
mean airborne asbestos concentration dur-
ing procedures on floors in poor condition
was approximately 12 times greater than
the mean baseline concentration. The 95%
confidence interval for this proportion is
(6.4, 22). The lower confidence limit is
greater than 1, which indicates this is a
statistically significant increase. Similarly,
when averaged over floor care procedure,
the mean airborne asbestos concentra-
tion during procedures on floors in good
condition was approximately 10 times
greater than the mean baseline concen-
tration. This increase is also statistically
significant.
Overall, ultra high-speed burnishing and
wet-stripping resulted in an 11-fold in-
crease, on average, in airborne asbestos
concentration. A 95% confidence interval
for the overall average concentration dur-
ing ultra high-speed burnishing and wet-
stripping expressed as a proportion of the
average baseline concentration is (7.1,
17.2). The lower confidence limit is greater
than 1, which indicates the increase is
statistically significant.
PCM Concentrations
The ultra high-speed burnishing opera-
tion produced a fine, pale yellow, powdery
dust from the wax and/or sealant. PCM
concentrations measured during ultra high-
speed burnishing were significantly higher
than those measured during stripping. The
elevated concentrations measured during
ultra high-speed burnishing were due pri-
marily to the white dust generated during
the process. The fine dust particles (pul-
verized wax/sealant) that measured greater
than 5 urn in length and had a length-to-
width aspect ratio of 3:1 were counted as
fibers (NIOSH Method 7400, A Counting
Rules). The corresponding TEM concen-
trations show that the PCM concentra-
tions do not reflect an accurate indication
of the airborne asbestos concentrations.
The 8-hr TWA concentrations were cal-
culated by assuming zero exposure be-
yond that which was measured during the
experiment. Although none of the 8-hr
-------
E
O
a
E
O
JO
W
a'
o
!§ 0.001
0.0001
Sample Period
Baseline • During
0.01
Poor Good Poor
Prepared Floor Care Condition
Good
Figure 2. Average airborne asbestos concentrations measured before and during ultra high-speed burnishing and wet-stripping of floors in prepared
conditions.
TWA concentrations measured during wet-
stripping (after ultra high-speed burnish-
ing) exceeded the OSHA PEL of 0.1 f/cm3
for total fibers, all of the 8-hr TWA con-
centrations measured during ultra high-
speed burnishing exceeded the OSHA
PEL. These exceedances, however, were
due to the excess nonasbestos-contain-
ing particulate generated during the bur-
nishing process and not to elevated
airborne asbestos particles.
Conclusions
The following are the principal conclu-
sions reached during this study:
1) Larger increases in airborne asbes-
tos concentrations were observed dur-
ing wet-stripping than during
low-speed spray-buffing of floors in
pre-existing condition. The average
airborne asbestos concentration mea-
sured during low-speed spray-buffing
was approximately 11 times greater
than the average baseline concentra-
tion. The average airborne asbestos
concentration measured during wet-
stripping was approximately 186 times
greater than the respective average
baseline concentration. In both cases,
the increases in airborne asbestos
concentrations were statistically sig-
nificant.
2) The average airborne asbestos con-
centration measured during low-speed
spray-buffing of floors in the three
levels of prepared floor-care condi-
tions (poor, medium, and good) was
approximately 2.6 times higher than
the average baseline concentration.
This increase was statistically signifi-
cant.
3) The level of prepared floor care did
not significantly affect the airborne
asbestos concentrations measured
during low-speed spray-buffing. Al-
though the average increase in air-
borne asbestos concentrations tended
to decrease as the level of floor care
improved, the differences due to the
three levels of floor care were not
statistically significant.
4) Wet-stripping of floors in medium and
good condition (after low-speed spray-
5)
buffing) resulted in statistically signifi-
cant increases in airborne asbestos
concentrations. The average airborne
asbestos concentration measured dur-
ing wet-stripping of floors in medium
condition was approximately 108 times
higher than the average baseline con-
centration, whereas the average air-
borne asbestos concentration
measured during wet-stripping of
floors in good condition was approxi-
mately 8.0 times higher than the av-
erage baseline concentration. The
increase was statistically significant
for both floor-care conditions.
A second layer of sealant appears to
significantly decrease airborne asbes-
tos levels during wet-stripping (after
low-speed spray buffing). Larger in-
creases in airborne asbestos concen-
trations were observed during
wet-stripping of floors in medium con-
dition than on floors in good condi-
tion. The average increase (relative
to baseline measurements) in airborne
asbestos concentration during wet-
stripping of floors in medium condi-
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tion was approximately 14 times
greater than during wet-stripping of
floors in good condition. This differ-
ence was statistically significant.
6) Overall, larger increases in airborne
asbestos concentrations were ob-
served during wet-stripping than dur-
ing low-speed spray-buffing. The
average increase (relative to baseline
measurements) in airborne asbestos
concentration during wet-stripping was
approximately 18 times greater than
during low-speed spray-buffing. This
difference was statistically significant.
7) None of the individual airborne total
fiber concentrations (determined by
PCM) measured during low-speed
spray-buffing and wet-stripping of
floors in pre-existing or prepared con-
ditions exceeded the OSHA PEL of
0.1 f/cm3. The 8-hr TWA concentra-
tions, calculated by assuming zero
exposure beyond that which was mea-
sured during the experiment, were
also below the OSHA PEL. Although
all of the computed 8-hr TWA per-
sonal sample results for the condi-
tions of this study were below the
OSHA PEL, it is noted that these tile
were of low asbestos content and in
good condition, and that no other as-
bestos exposure activity was as-
sumed. TEM analysis showed higher
exposures to fibers predominantly less
than 5 urn in length, whereas these
shorter fibers were not counted by
PCM. Caution should be exercised in
extrapolating the PCM measurements
collected during this study to condi-
tions at other sites.
8) When averaged over floor-care con-
dition (poor and good), a 14-fold in-
crease in airborne asbestos
concentration was observed during
ultra high-speed burnishing, whereas
a 9-fold increase was observed dur-
ing wet stripping. The difference be-
tween the increase in airborne
asbestos concentrations measured
during ultra high-speed burnishing and
that measured during wet-stripping
was not statistically significant.
9) When averaged over the maintenance
procedure (ultra high-speed burnish-
ing and wet-stripping), a 12-fold in-
crease in airborne asbestos
concentration was observed during
procedures on floors in poor condi-
tion, whereas a 10-fold increase was
observed during procedures on floors
in good condition. The difference be-
tween the increase in airborne as-
bestos concentrations measured on
floors in poor condition and those on
floors in good condition was not sta-
tistically significant.
10) Overall, ultra high-speed burnishing
and wet-stripping resulted in an 11-
fold increase, on average, in airborne
asbestos concentration. This increase
was statistically significant.
11) None of the individual airborne total
fiber concentrations (determined by
PCM) measured during wet-stripping
(after ultra high-speed burnishing) of
floors in prepared condition exceeded
the OSHA PEL of 0.1 f/cm3. The 8-hr
TWA concentrations based on these
measured levels and sample dura-
tions also did not exceed the OSHA
PEL.
12) All of the individual airborne total fi-
ber concentrations (determined by
PCM) measured during ultra high-
speed burnishing of floors in prepared
condition exceeded the OSHA PEL
of 0.1 f/cm3. The 8-hr TWA concen-
trations based on these measured lev-
els and sample durations (assuming
zero concentration beyond that which
was measured during the experiment)
would also exceed the OSHA PEL.
These exceedances, however, were
due to the nonasbestos-containing
particulate generated during the ultra
high-speed burnishing process and
not to elevated airborne asbestos par-
ticles.
13) This study was conducted on resilient
floor tile containing a relatively low
percentage of asbestos. That is, the
vinyl floor tile contained 3 to 5%
chrysotile asbestos, whereas vinyl
floor tile generally contains 3 to 25%
asbestos. Hence, it is conceivable that
floor tile with a higher percentage of
asbestos could result in higher levels
of airborne asbestos during routine
floor-care maintenance activities. The
results of this study should be inter-
preted accordingly.
Recommendations
1) Floor-care treatments systems that in-
clude the use of a sealant over which
the wax or finish coats are applied
should be used on asbestos-contain-
ing resilient floor tile. Two or more
layers of sealant should be applied
as a base coat. The use of multiple
layers of sealant on asbestos-con-
taining floor tile can significantly lessen
airborne asbestos concentrations dur-
ing the mechanical removal of the
wax or finish from the floor.
2) Two or more layers of wax or finish
should also be applied to asbestos-
containing resilient floor tile. Although
to a lesser extent, multiple layers of
floor finish may also provide addi-
tional protection against asbestos re-
lease during low-speed spray-buffing
and ultra high-speed burnishing of
asbestos-containing resilient floor tile.
3) The results of this study further sup-
port the original U.S. EPA Recom-
mended Interim Guidance for
Maintenance of Asbestos-Containing
Floor Coverings issued on January
25, 1990. Machine stripping of as-
bestos-containing resilient floor tile
should be conducted only when nec-
essary. Wet-stripping of floors tends
to result in higher increases in air-
borne asbestos concentrations than
routine buffing procedures. Floors
should be kept adequately wet during
stripping. The floor machine should
be equipped with the least abrasive
pad possible to strip the wax or finish
coat from asbestos-containing floor
tile.
4) Workers responsible for the mainte-
nance of asbestos-containing floor tile
should be trained on the proper use
of the floor machines used for low-
speed spray-buffing, ultra high-speed
burnishing, and wet-stripping, the ap-
propriate buffing and stripping pads,
and the selected floor-care treatment
system. Workers should also be in-
formed of and follow appropriate op-
erations and maintenance (O&M) work
practices and procedures for the main-
tenance of asbestos-containing resil-
ient floor
The full report was submitted in fulfill-
ment of Contract No. 68-D2-0058, Work
Assignment No. 11-61 by Environmental
Quality Management, Inc. under the spon-
sorship of the U.S. Environmental Protec-
tion Agency.
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John R. Kominsky, Ronald W. Freyberg, and James M. Boiano are with
Environmental Quality Management, Inc., Cincinnati, OH 45240
Alva Edwards is the Technical Project Officer (see below) and
Thomas Sharp is the EPA Project Officer
The complete report, entitled "Airborne Asbestos Concentrations During
Buffing, Burnishing, and Stripping of Resilient Floor Tile," (Order No.
PB95-260212; Cost $27.00, subject to change) will be available only
from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Technical Project Officer can be contacted at:
National Risk Management Research Laboratory
U. S. Environmental Protection Agency
Cincinnati, OH 45268
United States
Environmental Protection Agency
Technology Transfer and Support Division (CERI)
Cincinnati, OH 45268
Official Business
Penalty for Private Use
$300
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
EPA/600/SR-95/121
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