Project Summary

United States

Environmental Protection

Agency

Airborne Asbestos

Concentrations During Buffing,

Burnishing, and Stripping of

Resilient Floor Tile

John R. Kominsky, Ronald W. Freyberg, and James M. Boiano

National Risk Management

Research Laboratory

Cincinnati, OH 45268

Research and Development

 This study was conducted to evaluate airborne asbestos 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.

Airborne asbestos concentrations were

measured before and during each floorcare procedure to determine the magnitude 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 Administration (OSHA) Permissible Exposure

Limit (PEL) of 0.1 f/cm3, 8-hr. timeweighted average (TWA). Low-speed

spray-buffing and wet-stripping were

evaluated on pre-existing floor conditions and three levels of prepared floorcare 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 condition, hence it is conceivable that floor

tile with higher percentages of asbestos could result in higher levels of airborne asbestos during routine floor

care maintenance activities. TEM analysis showed higher exposures to fibers

predominantly less than 5 μm in length,

whereas these shorter fibers were not

counted by PCM.

This study shows that low-speed

spray-buffing, ultra high-speed burnishing, and wet-stripping of asbestos-containing resilient floor tile can be sources

of airborne asbestos in building air.

The results suggest that multiple layers of sealant applied to the floor prior

to the application of the floor finish

can reduce the release of asbestos fibers during polish removal. The results

of this study further support the U.S.

EPA Recommended Interim Guidance

for Maintenance of Asbestos-Containing Floor Coverings.

This Project Summary was developed

by EPA’s National Risk Management

Research Laboratory, Cincinnati, OH,

to announce key findings of the research project that is fully documented

in a separate report of the same title

(see Project Report ordering information at back).

Introduction

Three principal types of preventive maintenance are routinely performed on resilient floor tile: spray-buffing, ultra

high-speed burnishing, and wet-stripping

followed by refinishing. Spray-buffing is

the restorative maintenance of a previously polished floor by use of a floorpolishing 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 dryness. 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

EPA/600/SR-95/121 August 1995
2

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 asbestos 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 concentrations during polish removal from

asbestos-containing resilient floor tile

in pre-existing floor condition.

• To determine and compare the airborne asbestos concentrations during low-speed spray-buffing of

asbestos-containing resilient floor tile

in poor, medium, and good floor conditions.

• To determine and compare airborne

asbestos concentrations during polish removal after low-speed spraybuffing of asbestos-containing resilient

floor tile in medium and good conditions using a manual floor machine.

• To determine and compare the airborne asbestos concentrations during ultra high-speed burnishing of

asbestos-containing resilient floor tile

in poor and good floor conditions.

• To determine and compare the airborne asbestos concentrations during polish removal after ultra

high-speed burnishing of asbestoscontaining 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 Permissible 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 spraybuffing 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 unoccupied building located at the decommissioned 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 approximately 5% chrysotile asbestos. Representatives of the Chemical Specialties

Manufacturers Association (CSMA) and a

floor products manufacturer visually inspected the physical condition of the floor.

Their inspection focused on the evenness

of the floor plane and the physical condition of the tile. They concluded that the

floor was acceptable for the proposed

study.

Configuration for Low-speed

Spray-buffing and Wetstripping 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 airtight 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 polyethylene 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 concentrations to background levels after each experiment.

Configuration for Ultra HighSpeed Burnishing and WetStripping Experiments

Upon completion of the low-speed

spray-buffing and wet-stripping experiments, the test area was reconfigured to

accommodate the ultra high-speed burnishing 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 filtration units were placed in the hallway outside of the test room to ventilate the test

room and reduce the airborne asbestos

concentrations to background levels after

each experiment. The units were operated during the preparation phase of each

experiment but not during the actual burnishing or wet-stripping experiments. All

three HEPA units discharged the air outdoors 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 evaluated on the pre-existing floor-care condition. Pre-existing condition was the

condition of the floor as it existed in the

room prior to evaluating the prepared floorcare conditions. Pre-existing floor conditions consisted of an undetermined number

of coats of a Carnauba-type, buffable polish on the floor tile. Low-speed spraybuffing of the pre-existing floor-care

condition was evaluated five times, once

in each of the five test rooms. Wet-stripping (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 evaluated 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 conditions: 1) poor floor-care condition, 2)

medium floor-care condition, and 3) good

floor-care condition. Poor floor-care condition 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 defined as a floor with two coats of sealant

and three coats of polish. Floor-care conditions 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-buffing was evaluated on two levels of floor-
3

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 asbestos concentrations during polish removal. 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 evaluated 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 defined as a floor with two coats of sealant

and four coats of polish. Floor-care conditions were defined in consultation with the

CSMA and other representatives of floorcare chemicals manufacturers. Each floorcare condition was evaluated four times

to yield a total of eight experiments.

Wet-stripping after ultra high-speed burnishing 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 lowspeed and ultra high-speed experiments

based on the varying nature of the two

floor-care procedures. Although this precluded 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 conduct a practical evaluation of each floorcare 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 concentration measured during low-speed spraybuffing, 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 collected 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 μm

mixed cellulose ester (MCE), one open

0.8 μm MCE) were also collected during

each experiment as a control for filter contamination.

Sampling Methods

The area air samples (baseline and outdoor) were collected on open-face, 25-

mm diameter, 0.45-μm pore-size, MCE

filters with a 5-μm pore-size cellulose support pad contained in a three-piece cassette. 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 experiment on the individual operating the

floor machine. Two samples were collected

on open-face, 25-mm diameter, 0.8-μm

poresize MCE membrane filters and cellulose support pad contained in a threepiece cassette with a 50-mm conductive

extension cowl. These two samples were

analyzed by phase contrast microscopy

(PCM). Three additional personal breathing zone samples were collected on an

open-faced, 25-mm-diameter, 0.45 μm

pore-size MCE filters with a 5 μm poresize MCE diffusing filter and a cellulose

support pad contained in a 3-piece cassette. These three samples were analyzed

by transmission electron microscopy

(TEM).

Analytical Methods

Baseline Samples

The MCE filters were prepared and analyzed in accordance with the nonmandatory

TEM method specified in the AHERA Final 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 represented by the finding of a single structure) 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 completing the grid square in which the 100th

asbestos structure was found.

Personal Breathing Zone

Samples

The two 0.8-μm pore-size MCE filters

used to collect the personal breathing zone

samples were analyzed by PCM. These

samples were prepared and analyzed according to NIOSH Method 7400 (Revision

3, June 5, 1989, National Institute for Occupational Safety and Health Manual of

Analytical Methods). The analytical sensitivity was approximately 0.01 fibers/cm3

 of

air sampled. The three personal breathing

zone samples collected on 0.45 μm

poresize MCE filters were analyzed by

TEM as described above for the baseline

samples.

Statistical Methods

The relative change in airborne asbestos concentration was measured by the

ratio of the average concentration during

the specific maintenance procedure to the

average concentration before the maintenance 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-custody 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 procedures documented each sample from

the time of its collection until its receipt by

the analytical laboratory. Internal laboratory records then documented the custody of the sample through its final

disposition. Specific quality assurance procedures outlined in the AHERA rule were

used to ensure the precision of the collection 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-stripping were first evaluated on the pre-existing 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 indicate that the specific maintenance proce-
4

dure had a statistically significant effect

on airborne asbestos concentrations measured during the procedure (p=0.0128).

Specifically, larger increases in airborne

asbestos concentrations were observed

during wet-stripping than during spray-buffing. The estimated airborne asbestos concentrations during spray-buffing and

wet-stripping as a proportion of the respective baseline concentrations were calculated 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 interval 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 proportion is (44, 788). The lower 95% confidence 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 measured during wet-stripping. The 8-hr TWA

concentrations associated with the measured 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 spraybuffing and from 0.0003 to 0.003 f/cm3

during wet-stripping of floors in pre-existing condition. None of the 8-hr TWA concentrations 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, considerably higher exposures were shown by the

personal breathing zone samples analyzed

by TEM. Two primary reasons explain why

the TEM concentrations were considerably higher than the PCM concentrations.

First, PCM cannot detect fibers thinner

than 0.25 μm in width. Second, the PCM

method used in this study (i.e., NIOSH

7400) does not count fibers shorter than 5

μm 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

μm in length and would therefore not be

counted by the PCM method.

Caution should be exercised in extrapolating 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 assumed.

Prepared Floor Conditions

TEM Concentrations

Figure 1 illustrates the overall average

(geometric mean) concentrations measured before and during low-speed spraybuffing and wet-stripping on floors in

prepared floor conditions. Although the

mean relative increase in airborne asbestos concentrations during low-speed spraybuffing tended to decrease as the floor

care condition improved (i.e., poor condition 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 average airborne asbestos concentration during low-speed spray-buffing was

approximately 2.6 times higher than the

average baseline concentration. This increase was statistically significant

(p=0.0017). A 95% confidence interval for

the mean airborne asbestos concentration during spray-buffing as a proportion

of the baseline concentration showed that

the overall mean airborne asbestos conFigure 1. Average airborne asbestos concentrations during low-speed spraying of floors in prepared conditions.

10

1

0.1

0.01

0.001

Sample Period

Baseline During

Poor Medium

Low-Speed Spray-Buffing Wet-Stripping

Good Medium Good

Prepared Floor Care Condition
5

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 airborne asbestos concentrations (i.e., compared to baseline measurements) was

approximately 14 times greater, on average, during wet-stripping of floors in medium condition than during wet-stripping

of floors in good condition.

The estimated airborne asbestos concentrations during wet stripping of floors

in medium and good condition as a proportion of the respective baseline concentrations were calculated along with the

corresponding 95% confidence interval.

The average airborne asbestos concentration measured during wet-stripping of

floors in medium condition was approximately 108 times greater than the average 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 average airborne asbestos concentration measured during wet-stripping of floors in good

condition was approximately 8 times

greater than the average baseline concentration. 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 stripping 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 concentrations were observed during wet-stripping

of floors in both medium and good condition, the extra layer of sealant on floors in

good condition appears to significantly decrease the airborne asbestos levels.

Overall, significantly larger increases

(p=0.0001) in airborne asbestos concentrations were observed during wet-stripping than during low-speed spray-buffing

(this comparison was restricted to floors

in medium and good condition since wetstripping was not evaluated on floors in

poor condition). The relative increase in

airborne asbestos concentrations was

approximately 18 times greater, on average, during wet-stripping than during lowspeed 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 measured 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 experiment. 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 asbestos content and in good condition, and

that no other asbestos exposure activity

was assumed. TEM analysis showed

higher exposures to structures predominantly less than 5 μm 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 μm in length and would not

be counted by the PCM method. Therefore, caution should be exercised in extrapolating 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 procedure (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, similar increases in airborne asbestos concentrations were seen during ultra

high-speed burnishing and wet-stripping

of floors in both poor and good condition.

No floor condition or maintenance procedure resulted in significantly higher or lower

increases in mean airborne asbestos

concentration.

The estimated airborne asbestos concentrations during ultra high-speed burnishing and wet-stripping as proportions

of the respective baseline concentrations

were calculated along with the corresponding 95% confidence interval. When averaged over floor care condition (good, poor),

the mean airborne asbestos concentration 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 concentration during wet-stripping was approximately

9 times greater than the mean baseline

concentration. This increase is also statistically significant.

The estimated airborne asbestos concentrations during procedures on floors in

poor and in good condition as proportions

of the respective baseline concentrations

were calculated along with the corresponding 95% confidence interval. When averaged over floor care procedure (ultra

high-speed burnishing, wet-stripping), the

mean airborne asbestos concentration during 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 concentration during procedures on floors in good

condition was approximately 10 times

greater than the mean baseline concentration. This increase is also statistically

significant.

Overall, ultra high-speed burnishing and

wet-stripping resulted in an 11-fold increase, on average, in airborne asbestos

concentration. A 95% confidence interval

for the overall average concentration during ultra high-speed burnishing and wetstripping 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 operation produced a fine, pale yellow, powdery

dust from the wax and/or sealant. PCM

concentrations measured during ultra highspeed burnishing were significantly higher

than those measured during stripping. The

elevated concentrations measured during

ultra high-speed burnishing were due primarily to the white dust generated during

the process. The fine dust particles (pulverized wax/sealant) that measured greater

than 5 μm in length and had a length-towidth aspect ratio of 3:1 were counted as

fibers (NIOSH Method 7400, A Counting

Rules). The corresponding TEM concentrations show that the PCM concentrations do not reflect an accurate indication

of the airborne asbestos concentrations.

The 8-hr TWA concentrations were calculated by assuming zero exposure beyond that which was measured during the

experiment. Although none of the 8-hr
6

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 wetstripping (after ultra high-speed burnishing) exceeded the OSHA PEL of 0.1 f/cm3

for total fibers, all of the 8-hr TWA concentrations measured during ultra highspeed burnishing exceeded the OSHA

PEL. These exceedances, however, were

due to the excess nonasbestos-containing particulate generated during the burnishing process and not to elevated

airborne asbestos particles.

Conclusions

The following are the principal conclusions reached during this study:

1) Larger increases in airborne asbestos concentrations were observed during wet-stripping than during

low-speed spray-buffing of floors in

pre-existing condition. The average

airborne asbestos concentration measured during low-speed spray-buffing

was approximately 11 times greater

than the average baseline concentration. The average airborne asbestos

concentration measured during wetstripping was approximately 186 times

greater than the respective average

baseline concentration. In both cases,

the increases in airborne asbestos

concentrations were statistically significant.

2) The average airborne asbestos concentration measured during low-speed

spray-buffing of floors in the three

levels of prepared floor-care conditions (poor, medium, and good) was

approximately 2.6 times higher than

the average baseline concentration.

This increase was statistically significant.

3) The level of prepared floor care did

not significantly affect the airborne

asbestos concentrations measured

during low-speed spray-buffing. Although the average increase in airborne 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 spraybuffing) resulted in statistically significant increases in airborne asbestos

concentrations. The average airborne

asbestos concentration measured during wet-stripping of floors in medium

condition was approximately 108 times

higher than the average baseline concentration, whereas the average airborne asbestos concentration

measured during wet-stripping of

floors in good condition was approximately 8.0 times higher than the average baseline concentration. The

increase was statistically significant

for both floor-care conditions.

5) A second layer of sealant appears to

significantly decrease airborne asbestos levels during wet-stripping (after

low-speed spray buffing). Larger increases in airborne asbestos concentrations were observed during

wet-stripping of floors in medium condition than on floors in good condition. The average increase (relative

to baseline measurements) in airborne

asbestos concentration during wetstripping of floors in medium condi1

0.1

0.01

0.001

0.0001

Prepared Floor Care Condition

Sample Period

Baseline During

Poor Good Poor Good

High-Speed Burnishing Wet-Stripping
7

tion was approximately 14 times

greater than during wet-stripping of

floors in good condition. This difference was statistically significant.

6) Overall, larger increases in airborne

asbestos concentrations were observed during wet-stripping than during 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 conditions exceeded the OSHA PEL of

0.1 f/cm3. The 8-hr TWA concentrations, calculated by assuming zero

exposure beyond that which was measured during the experiment, were

also below the OSHA PEL. Although

all of the computed 8-hr TWA personal sample results for the conditions 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 asbestos exposure activity was assumed. TEM analysis showed higher

exposures to fibers predominantly less

than 5 μm 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 conditions at other sites.

8) When averaged over floor-care condition (poor and good), a 14-fold increase in airborne asbestos

concentration was observed during

ultra high-speed burnishing, whereas

a 9-fold increase was observed during wet stripping. The difference between 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 burnishing and wet-stripping), a 12-fold increase in airborne asbestos

concentration was observed during

procedures on floors in poor condition, whereas a 10-fold increase was

observed during procedures on floors

in good condition. The difference between the increase in airborne asbestos concentrations measured on

floors in poor condition and those on

floors in good condition was not statistically 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 durations also did not exceed the OSHA

PEL.

12) All of the individual airborne total fiber concentrations (determined by

PCM) measured during ultra highspeed 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 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 particles.

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 interpreted accordingly.

Recommendations

1) Floor-care treatments systems that include the use of a sealant over which

the wax or finish coats are applied

should be used on asbestos-containing 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-containing floor tile can significantly lessen

airborne asbestos concentrations during 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 asbestoscontaining resilient floor tile. Although

to a lesser extent, multiple layers of

floor finish may also provide additional protection against asbestos release during low-speed spray-buffing

and ultra high-speed burnishing of

asbestos-containing resilient floor tile.

3) The results of this study further support the original U.S. EPA Recommended Interim Guidance for

Maintenance of Asbestos-Containing

Floor Coverings issued on January

25, 1990. Machine stripping of asbestos-containing resilient floor tile

should be conducted only when necessary. Wet-stripping of floors tends

to result in higher increases in airborne 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 maintenance of asbestos-containing floor tile

should be trained on the proper use

of the floor machines used for lowspeed spray-buffing, ultra high-speed

burnishing, and wet-stripping, the appropriate buffing and stripping pads,

and the selected floor-care treatment

system. Workers should also be informed of and follow appropriate operations and maintenance (O&M) work

practices and procedures for the maintenance of asbestos-containing resilient floor

The full report was submitted in fulfillment of Contract No. 68-D2-0058, Work

Assignment No. II-61 by Environmental

Quality Management, Inc. under the sponsorship of the U.S. Environmental Protection Agency.
8

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

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Environmental Protection Agency

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EPA/600/SR-95/121