Report No. PL-97-7
TABLE
OF CONTENTS
EXECUTIVE SUMMARY......................................................................................................
1 1.0 OBJECTIVES OF STUDY ..........................................................................................
4 2.0 SAMPLING PLAN AND METHODOLOGY............................................................ 4 2.1 CHOICE OF ANALYTES...................................................................................
4 2.2 SAMPLING AND
ANALYTICAL METHODOLOGY.......................................
4 2.3 FACILITY DESCRIPTION.................................................................................
6 2.4 TESTING.............................................................................................................
7 3.0 RESULT SUMMARY..................................................................................................
7 4.0 DISCUSSION OF RESULTS......................................................................................
9 4.1 PERSEPECTIVES REGARDING
PELs AND TLVs............................................ 9 4.2 POTENTIAL HEALTH EFFECTS
OF POLYPROPYLENE DUST..................
10 4.3 ANALYSIS OF RESULTS................................................................................
11
5.0 CONCLUSIONS OF STUDY....................................................................................
12 6.0 REFERENCES...........................................................................................................
14 7.0 ACKNOWLEDGMENTS..........................................................................................
16
APPENDICES
APPENDIX A FIELD SAMPLING DATA SHEETS APPENDIX B FIELD SAMPLING DATA/CHAIN OF CUSTODY FORM SUBMITTED TO LABORATORY APPENDIX C SAMPLING DATA CALCULATION SPREADSHEETS APPENDIX D LABORATORY REPORTS APPENDIX E SAMPLING EVENT OBSERVATIONS REGARDING DUST GENERATION APPENDIX F RESPIRATOR TRAINING REQUIREMENTS IN WASHINGTON STATE
EXECUTIVE SUMMARY
This study samples indoor dust levels generated
by sortation and densification operations at a small-scale plastic
recycling facility. Both respirable
nuisance dust and total nuisance dust levels are observed as time-weighted
averages on two typical production days during which polypropylene
film is being densified. The
goal of the study is to gather basic information regarding dust levels,
in order to assist in the evaluation and selection of adequate dust
control options. Testing is performed for informational purposes
only, and the results are not statistically valid for the demonstration
of compliance or noncompliance with any industrial standard. For the purposes of this study, the polypropylene dust generated during the densification process is considered to be in the category of a nuisance dust, i.e., a dust that is generally innocuous and not recognized as the cause of serious pathological conditions. Because exposure to high concentrations of any dust, regardless of chemical toxicity level, can cause respiratory disruption, the United States Occupational Safety and Health Administration (OSHA), under the Code of Federal Regulations 29 CFR 1910.1000, regulates exposure to nuisance dust in the workplace. Allowable exposure is regulated via permissible exposure limits (PELs), or time-weighted averages (TWAs) that are not to be exceeded for an 8-hour workday within a 40-hour workweek. Regulatory exposure levels exist for both total nuisance dust and respirable nuisance dust. Federal
regulations require that exposure to any regulated indoor air contaminant,
including nuisance dust, not exceed the documented PELs. In addition, individual states have the ability
to set PELs that are more restrictive than the federal regulations.
Compliance with PELs can be achieved through administrative
controls (operational training, employee rotation to reduce exposure,
etc.) and/or engineering controls (site ventilation, use of respirators,
etc).
While
the results of this study cannot be used to determine compliance or
noncompliance with PELs, the measurements provide estimates of the
magnitude and distribution of dust levels in the facility. A preliminary review of available research indicates that human
physiological responses to polypropylene fibers appear to be similar
to other "inert" types of fibers and dusts.
However, evidence is not available to preclude the potential
for harmful effects, particularly regarding exposures to dust concentrations
near or above PELs. In high
concentrations, any nuisance dust can cause respiratory disruptions
by restricting respiratory
In this study, four respirable nuisance dust samples and fourtotal nuisance dust samples are collected during two typical processing days. Dust measurements are taken in the densification area, which exhibits the highest level of visible dust, and also in the sorting area, which exhibits a much lower level of visible dust. During the two tests, the densification process operates at 86% and 97% respectively of the rated production capacity of 1,000 pounds per hour. Respirable dust level measurements in the densifier area, the sorting area, and the forklift operations area, range from 0.13 milligrams per cubic meter (mg/m3 ) to 1.20 mg/m 3 For comparative purposes, the measured respirable dust values are well below the U.S. Occupational Safety and Health Administration (OSHA) and Washington Industrial Safety and Health Act (WISHA) PEL for respirable nuisance dust of 5 mg/m3
Total dust level measurements in the sorting area range from 0.22 mg/m3 to 0.27 mg/m3, and in the densifier area from 12.83 mg/m3 to 18.20 mg/m3. For comparative purposes, the measured total dust values in the sorting area are well below the OSHA PEL for total nuisance dust of 15 mg/m3 and the WISHA PEL of 10 mg/m3; however, the measured total dust values in the densifier area exceed the PEL. Higher total dust values in the densifier area indicate that the facility could benefit substantially from dust control measures targeted toward the densification equipment. This
study is not a statistical sampling, and thus the measurements are
invalid for the determination of compliance or noncompliance with
The respirable nuisance dust measurements taken in all test
areas are 76%
to 97% Comparing respirable and total dust
measurements, this facility’s polypropylene film densification process
generates more nonrespirable than respirable particles. These nonrespirable particles are also confined
to the densifier equipment area, indicating that a localized ventilation
solution, such as a vacuum hood system, may be sufficient to adequately
reduce excess dust. If respirators
are selected as a means of controlling dust exposure in Washington
State, then the appropriate minimum requirements must be met.
[2]
1.0
The
objective of this study is to gather basic information regarding dust
levels, in order to assist in the evaluation and selection of adequate
dust control options for a recycled polypropylene film densification
process. The measurements are performed for informational
purposes only, and the results are not statistically valid for the
demonstration of compliance or noncompliance with federally regulated
permissible exposure limits. Other
potential indoor air contaminants are not considered during this study.
2
2.1
Other
potential indoor air contaminants are not addressed in this study. Research indicates that the high-temperature
heating of plastics (i.e., above 200°C), such as heating that occurs during initial processing
or incineration, can result in the release of various chemicals.
These chemicals may include monomers, additives, plasticizers,
or other
All samples are collected using personal monitoring pumps and pre weighed polyvinyl chloride filters, placed in preloaded cassettes. The pore size of the filters is five microns, in accordance with the applicable National Institute of Occupational Safety and Health (NIOSH) analytical methods. The filters are 152 microns thick, with a typical 99.94% aerosol retention. Aluminum cyclones, made by Mine Safety Appliances Co. (MSA), are used to restrict the particle size collected for the respirable dust samples. The following analytical methods are used:
Both methods involve weighing the filters after samples are collected, and comparing with the pre-sample filter weights. Time-weighted-average results are calculated in the accredited testing laboratory using volume data (the volume of air pumped through the filter) from the test site. The sampling plan for this study is loosely based on an initial sampling strategy known among industrial hygienists as an "exposure screening program", or “screening." The purpose of “screening” is to selectively obtain exposure estimates for "maximum-risk" workers [3] In this study, of the eight employees in the processing area, the densifier operator appears to be subject to more visible dust exposure than any of the other seven employees. These seven other employees appear to have a similarly reduced exposure to visible dust, when compared with the densifier operator. A true “screening” program (which requires a 90% probability that the sample contains at least one employee in addition to the "high-risk" employee, in the top 10% of the exposures for that group) would have required sampling six >of the seven additional employees. Because the goal of this project is to obtain basic information to assist in the evaluation of dust control options, such a large sample size is not required. American Society for Testing
and Materials (ASTM) Standard D 4532-92 is used as a guideline for
sampling respirable dust.
[4]
Although much of this method relates to laboratory procedures,
the guidelines on sampling are followed to the maximum extent possible.Specifically,
the pumps run for fifteen minutes before sampling, to stabilize the
flow rate. Airflow through the cartridges is measured with a calibrated
rotometer three to four times during the sampling events. A flow rate
of 1.7 liters per minute is maintained as closely as possible. An
attempt is made to keep the cyclones and filter cartridges within
the prescribed worker's breathing zone of 300 millimeters from the
eyes. However, because the cyclone interferes with employee activities
that involve repeated bending, the limits of this breathing zone may
be slightly extended. The testing procedures are designed to measure conditions over the duration of two sampling events. The sampling events occur on two different days, over a period of at least seven hours for each sample unit. When calculating the volume of air pumped through the filters, time spent at normal lunch or breaks is not subtracted. Full plant production capacity for polypropylene film densification at the test site is rated at 6,500 pounds in 6.5 hours, or 1,000 pounds per hour. The production capacity for the two sampling days is 858 pounds per hour (86% of capacity) and 973 pounds per hour (97% of capacity). Two respirable nuisance dust samples and twototal nuisance dust samples are collected in the densification area. One respirable nuisance dust sample and two total nuisance dust samples are collected in the sorting area. One respirable nuisance dust sample is collected from the forklift operator, whose responsibilities require transporting materials between the densification area and the sorting area. During the sampling event, participating employees are instructed to maintain “normal” working conditions, since the testing goal is to sample “normal” conditions to the maximum extent possible. Observations are made periodically by the test director during the sampling event to ensure that the monitors are worn properly and that the instruments are functioning correctly. Observations are also made periodically by the facility supervisor to ensure that normal work conditions are being maintained by employees during the testing.
2 Eight
2 Four
Data collected during the sampling events is
provided in Appendices A through C.
Appendix A: Field Sampling Data Sheets, 3.0 SUMMARY OF RESULTS
TABLE 3
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