Airborne Asbestos Concentrations During Buffing of Resilient Floor Tile in New Jersey Schools

Donald R. Gerber, Gary J. Centifonti, Richard M. Ritota, James A. Brownlee
   New Jersey Department of Health
   Consumer and Environmental Health Services
 

John R. Kominsky, Ronald W. Freyberg
   Environmental Quality Management, Inc.
 

Roger C. Wilmoth, Bruce A. Hollett
   National Risk Management Research Laboratory
   U.S. Environmental Protection Agency
 

Abstract

Although asbestos-containing resilient floor tiles are considered nonfriable, the frictional forces exerted on the tile during routine maintenance operations can generate asbestos-containing structures. The New Jersey Department Of Health and Senior Services - Consumer and Environmental Health Services (NJDOH) and the U.S. Environmental Protection Agency's National Risk Management Research Laboratory (EPA-NRMRL) conducted a study to determine the level of airborne asbestos concentrations during routine spray-buffing of asbestos-containing floor tiles at seventeen schools in northern, central, and southern New Jersey. Although the schools selected do not represent a statistical random sample, they do represent a cross section of floor conditions and floor-care maintenance practices.

Increased airborne asbestos levels during spray-buffing were measured at twelve of the seventeen schools. The increase was statistically significant at seven of the seventeen schools. In eleven of the seventeen schools, the airborne asbestos levels during spray-buffing were above the AHERA clearance level of 0.02 s/cm3 in the proximity of the machine operator. Overall, the mean relative increase in airborne asbestos concentrations during spray-buffing with the high-speed machines (1000 to 1500 revolutions per minute) was statistically significantly higher than that during buffing with low-speed machines (175 to 330 revolutions per minute). More than 99 percent of the asbestos structures collected before and during spray-buffing were chrysotile; less than 1 percent were amphibole. Machine speed appeared to have a significant effect on the structure morphology of the airborne asbestos structures generated during spray-buffing. Results of the study indicate that spray-buffing can generate asbestos-containing particles from the surface of asbestos-containing resilient floor tile. The estimated 8-hour time-weighted average (TWA) of total fiber concentrations (0.093 f/cm3 maximum) in the breathing zone of the machine operators (as determined by phase contrast microscopy [PCM]) did not exceed the Occupational Safety and Health Administration (OSHA) level of 0.1 f/cm3.

Several recommendations were developed as a result of the conclusions from this study. Since buffing activities elevate airborne asbestos levels, until further research is conducted, guidance should indicate that spray-buffing be done at lower speeds (175-330 rpm) and less frequently (4-6 times per year). Schools/facilities should evaluate emerging technologies regarding floor care maintenance practices and products. The purpose is to further reduce the use of aggressive, mechanical procedures and minimize the possibility of fiber release due to floor care practices. The evaluations should include non-mechanical chemical strippers, waxes/finishes which are chemically removed and easily applied, and non-buffing waxes/finishes. Schools/facilities should ensure that workers performing maintenance procedures on asbestos-containing resilient floor tile are informed of the potential for elevated airborne asbestos levels as measured during this study and during four other EPA studies.