Steven P. Levine

Development and Evaluation of The Michigan Occupational Health and Safety Management System Assessment Instrument: A Universal OHSMS Performance Measurement Tool

A universal Occupational Health and Safety Management System (OHSMS) Assessment Instrument has been developed to measure the effectiveness of a wide range of OHSMSs. The development and evaluation of the instruments overall structure, its OHSMS principles, and its measurement criteria are presented in this article. Thirteen OHSMS and environmental management system (EMS) models were reviewed in an effort to define the OHSMS universe. Four of these models were selected as instrument input models. These models are (1) the Occupational Safety and Health Administrations Voluntary Protection Programs (VPP); (2) the British Standards Institutes OHSMS, BS 8800:1996; (3) the American Industrial Hygiene Associations OHSMS; and (4) the International Organization for Standardizations (ISO) EMS ISO 14001:1996. The instrument in its final form contains 27 sections, 118 OHSMS principles, and 486 measurement criteria. Evaluation of the instruments principles and measurement criteria was conducted by a 16-member pan...

Imaging Indoor Tracer-Gas Concentrations with Computed Tomography: Experimental Results with a Remote Sensing FTIR System

This work demonstrates for the first time the feasibility of computed tomography (CT) reconstructions of pollutant concentrations in a real room setting. A remote sensing Fourier transform infrared spectrometer was mounted on a moving base in a controlled ventilation chamber. A passive tracer was released from a point source into the room under constant ventilation conditions. A series of experiments gathered multiple path-averaged measurements in a two-dimensional plane for CT reconstruction. Simultaneous readings were gathered with a multiple-point sampling array for later comparison to the CT reconstructed concentrations. Good qualitative agreement between the reconstruction and point sample data was obtained. Limitations encountered due to the temporal resolution, size, and geometry of the experimental apparatus are clearly surmountable with better instrumentation.

Critical Review of Methods of Sampling, Analysis, and Monitoring for TDI and MDI

This article is a critical review of certain methods that have been used for the sampling, analysis, and monitoring of toluene diisocyanate (TDI) and methylene bisphenyl diisocyanate (MDI). Only those methods that have received relatively widespread application are addressed. The review includes a “tutorial style” discussion of basic definitions, and basic principles and procedures of quality control and metrology for sampling, analysis, and monitoring. Recommendations are given for future work in this area. Proper exposure assessment is critical in the risk analysis process, since both exposure and effect measurements are required.

Stationary and time-dependent indoor tracer-gas concentration profiles measured by OP-FTIR remote sensing and SBFM-computed tomography

Measurement of gas concentrations in indoor air using optical remote sensing (ORS) and computed tomography (CT) has been suggested but not thoroughly investigated. We present experiments in which one time-varying and 11 different steady-state tracer-gas concentration profiles were generated in a ventilated chamber and sampled in a horizontal plane by an open-path Fourier transform infrared (OP-FTIR) spectrometer for subsequent CT inversion. CT reconstructions were performed using the recently developed smooth basis function minimization (SBFM) technique. The CT reconstructions were compared with simultaneously gathered point-sample concentration measurements. Agreement between the two sampling methods was qualitatively very good, with concentration profiles generated by both methods showing the same features of peak location and shape. Quantitative agreement was generally good to within 50%. We discuss the sources of discrepancy and suggest directions for future research, especially with regard to monitoring time-dependent processes. With further refinements in the SBFM algorithm and improvements in optical remote sensing hardware, this technique promises to yield rapid and accurate measurements of the spatial distribution of gases in indoor environments.

The Limits of Detection for the Monitoring of Semiconductor Manufacturing Gas and Vapor Emissions by Fourier Transform Infrared (FTIR) Spectroscopy

To determine whether or not the Fourier transform infrared (FTIR) spectrometer is appropriate for industrial hygiene monitoring of the gases and vapors used in the semiconductor industry, the limits of detection (LOD) of these compounds were determined. The LODs were calculated using several widely used definitions to test whether the values obtained by the different methods would vary significantly. The experimental LOD values for the study compounds all were below their respective threshold limit values (TLVs®), and a significant difference between the LOD values calculated using the different definitions was noted. The FTIR spectrometer equipped with an indium antinomide/mercury cadmium telluride (InSb/MCT) sandwich detector, 20-m path length gas cell, and least squares fit (LSF) software is appropriate for monitoring semiconductor processing gases and vapors in the workplace.

THE USE OF A TRANSPORTABLE FOURIER TRANSFORM INFRARED (FTIR) SPECTROMETER FOR THE DIRECT MEASUREMENT OF SOLVENTS IN BREATH AND AMBIENT AIR—I: METHANOL

A transportable Fourier transform infrared (FTIR) spectrometer has been tested for analysis of methanol vapor in alveolar and ambient air. The instrument has been found to be accurate and precise for both uses. The regions used for methanol and CO2 quantification are in the vicinity of 950-1100 cm-1 and 2000-2100 cm-1, respectively. The results of a standard addition experiment show a correlation coefficient of 0.97-0.99 for methanol in alveolar or ambient air at the 30-200 ppm concentration level. For CO2 analysis in 23 alveolar air samples at the 6.1-7.6% concentration level, the mean difference in results between a nondispersive infrared (NDIR) spectrometer and the FTIR was -0.092% with a standard deviation of 0.273% (p greater than 0.1). Methanol concentrations in alveolar air paralleled simultaneous measurements of methanol concentration in blood. Overall, these preliminary results suggest that FTIR spectroscopy is a practical and efficient approach for simultaneous biological and area monitoring of human exposure to organic solvents.

A TRANSPORTABLE, REMOTE SENSING, INFRARED AIR-MONITORING SYSTEM

A transportable, remote sensing instrument has been built that is capable of performing real-time quantitative analysis of gas and vapor contaminants of workplace air. The emphasis in this system is on simplicity and sensitivity for use over pathlengths of up to 40 m. A method was developed to overcome the effect of nonanalyte species present in the background spectrum on the quantitation of analytes in the sample spectrum. In addition, results demonstrated that instrument response was proportional to the beam pathlength under homogeneous concentration conditions. The application of software capable of qualitative analysis was also demonstrated.

A Preliminary Evaluation of the Fourier Transform Infrared (FTIR) Spectrometer as a Quantitative Air Monitor for Semiconductor Manufacturing Process Emissions

Air monitors currently available for use at a semiconductor manufacturing facility, though accurate for a specific class of compounds, are of limited use for monitoring several classes of compounds (i.e., organic vapors, metal hydrides, and acid mists and gases) simultaneously. Preliminary research showed that the Fourier transform infrared (FTIR) spectrometer may be appropriate for detecting the various gases and vapors that could be present at a semiconductor manufacturing facility. A subset of the many gases and vapors used during the silicon processing sequence were diluted in air to sub-part-per-million (ppm) concentrations to simulate potential workplace conditions. The optimal wavelength region for quantitation, the effects of resolution on accuracy of quantitation, and the effect of spectral overlap on the accuracy of quantitation were studied. The preliminary results support the conclusion that the FTIR spectrometer is appropriate for quantitative air monitoring of selected compounds at a semicon...

Workplace and environmental air contaminant concentrations measured by open path Fourier transform infrared spectroscopy: a statistical process control technique to detect changes from normal operating conditions.

Open path Fourier transform infrared (OP-FTIR) spectroscopy is a new air monitoring technique that can be used to measure concentrations of air contaminants in real or near-real time. OP-FTIR spectroscopy has been used to monitor workplace gas and vapor exposures, emissions from hazardous waste sites, and to track emissions along fence lines. This paper discusses a statistical process control technique that can be used with air monitoring data collected with an OP-FTIR spectrometer to detect departures from normal operating conditions in the workplace or along a fence line. Time series data, produced by plotting consecutive air sample concentrations in time, were analyzed. Autocorrelation in the time series data was removed by fitting dynamic models. Control charts were used with the residuals of the model fit data to determine if departures from defined normal operating conditions could be rapidly detected. Shewhart and exponentially weighted moving average (EWMA) control charts were evaluated for use with data collected under different room air flow and mixing conditions. Under rapidly changing conditions the Shewhart control chart was able to detect a leak in a simulated process area. The EWMA control chart was found to be more sensitive to drifts and slowly changing concentrations in air monitoring data. The time series and statistical process control techniques were also applied to data obtained during a field study at a chemical plant. A production area of an acrylonitrile, 1,3-butadiene, and styrene (ABS) polymer process was monitored in near-real time. Decision logics based on the time series and statistical process control technique introduced suggest several applications in workplace and environmental monitoring. These applications might include signaling of an alarm or warning, increasing levels of worker respiratory protection, or evacuation of a community, when gas and vapor concentrations are determined to be out-of-control.

Optical Remote Sensing for Air Pollutants-Review

Air monitoring techniques need to be simple, unobtrusive, acquire real-time data, have increased sensitivity, and the ability to analyze many compounds simultaneously. Optical remote sensing techniques address many of these criteria for air monitoring methods. Optical remote sensing uses light energy between ultraviolet and midinfrared to detect and measure contaminants in situ. While optical remote monitoring techniques provide similar monitoring accuracy compared to conventional monitoring methods, they also provide certain unique advantages. Advantages and disadvantages of specific optical remote sensing techniques is discussed in this review, which focuses on the techniques most useful to the industrial hygiene profession. Detailed information about every technique will not be supplied; rather the review attempts to provide an understanding of the development of the remote sensing techniques, and briefly explains typical applications, so that readers can understand and evaluate applications appropriate to their work.