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workers, building, architect

NORA Manufacturing Sector Strategic Goals

927ZJLBa - Chemical Exposure Monitor With Indoor Positioning (CEMWIP)

Start Date: 10/1/2009
End Date: 9/30/2012

Principal Investigator (PI)
Name: Kenneth Brown
Phone: 513-841-4364
Organization: NIOSH
Sub-Unit: DART
Funded By: NIOSH

Primary Goals Addressed
5.0 9.0

Secondary Goal Addressed


Attributed to Manufacturing


Project Description

Short Summary

Chemical exposure monitor with indoor positioning project (CEMWIP) is a direct reading exposure method (DRM) that uses a personal PID chemical monitor with telemetry and an indoor positioning system to provide remote monitoring of a workers exposure to volatile organic chemical (VOC)s with position and time. The personal monitor continuously samples and analyzes the workers breathing zone air for VOCs while recording their position and time of exposure. Indoor positioning is accomplish using a radio transmitter attached to the personal monitor and receivers place in the ceiling corners of the room. The positioning receivers communicate with each other and a remote laptop using wireless local area network (WLAN) technology. The remote laptop calculates and visualizes the worker position and exposure level. Alerts can be programmed into the computer when exposures reach specified levels. The worker's exposure level, position, and time data are archived. The data can be reconstructed into historical dose maps for exposure assessment and engineering control research.


Year 1: Design the CEMWIP prototype.

A sole source justified contract would be established with the University of Cincinnati for research and development of the CEMWIP system. UC offers unique resources for this project that cannot be found elsewhere through its Center for Biosensors & Chemical Sensor (appx. p43) with its associated scientists like Professor William Heineman and Necati Kaval, Ph.D. (appx. p44). In turn, the output design work from the UC contract would be used as work descriptions for secondary competitively bid hardware and software development contracts used to assemble and debug the prototype. The second contract would be administered in the first year for hardware and software development. The goal here is to link the ToxiRAE® PID with the UWB position system for 3D personal monitoring of VOC workplace exposure. Some of the general tasks expected for making the prototype are to 1) modify the personal chemical sensor for telemetry 2) connect a positioning transmitter to the chemical sensor 3) develop wireless communication devices between the radio positioning receivers and to the remote computer, 4) evaluate the commercial positioning software for use in exposure assessment, and 5) modify software for archiving and analyzing the exposure data.

Year 2: Assemble the CEMWIP prototype.

Prototype assembly and development would continue in year two. Assembly will include testing the functions of each component of the system including the ability of the telemetry to transmit data. The prototype will be tested using UWB receivers in the corners of the room. The goal is to be able to monitor, in real time, the worker's position and the level of exposure they are experiencing. The software needs to be able to archive the data for later dose mapping analysis. So, during the second year the prototype will be assembled and evaluated for functionality.

Year 3: In-house evaluation of the CEMWIP prototype.

The CEMWIP prototype would be “beta tested” for positioning accuracy and precision using position markers placed in the simulated workplace setup in NIOSH's Ventilation Laboratory,. Dr. Shaw, statistician, would develop an experimental design for evaluating the three dimensional positioning of the stationary transceiver in the simulated workplace. Robert Voorhees and the software and hardware contractors would setup, demonstrate, evaluate, and modify the software and hardware. The in-house testing will provide system performance feedback to improve the method. Dr. Kenneth Mead would collaborate on the simulated facilities layout and the experimental design with engineering control ramifications in mind.

Positioning accuracy and precision would be evaluated in the Alice Hamilton Ventilation Laboratory, rooms B12 and B224. Once the system was assembled and supporting software developed, the radio receivers would be placed in the upper corners of the laboratory. A test stand looking much like a camera tripod with an extension pole would be moved to different X, Y coordinates of the room. The location would first be measured manually using certified tape measures. The CEMWIP chemical sensor would be mounted on the end of the tripod extension pole, and the height measured. The X, Y position in the room would be recorded, and after the height adjusted, the Z coordinate recorded. The tripod would be moved to different grid locations on the floor and the tests repeated. The number of X, Y, Z coordinate points that will be used has yet to be statistically designed. The end result will be an estimation of the systems accuracy and precision in measuring position.

The chemical sensor would then be tested in a simulated chemical release of a nontoxic vapors such as one or more room wick-deodorizers; the ventilation laboratory is designed to safely handle such simulations. A person would wear the PID and walk around the ventilation laboratory near the coordinates used for positioning accuracy and precision estimates to measure the VOCs levels in the room and those emitted by the wick-deodorizer. The exposure level, the sensors' position, and the time of exposure would be measured and sent to a remote laptop. An observer would monitor the person as they travelled the room and the VOC exposure levels they are experiencing. The results would determine if the system could measure the VOCs emitted by the room deodorizer and determined where the source wicks were located. The exposure data would be plotted in 3D with respect to x, y, and z coordinates to evaluate the ability to dose map the person's experience. In summary, the device would be personally tested using a low level nontoxic VOC release.

Traditional time weighted average (TWA) personal monitoring would be compared side by side to the real-time personal monitoring using the PID. A traditional absorbent and pump exposure method, like NIOSH NMAM method 1457, would be used on a stationary manikin placed side by side with the CEMWIP sensor during an exposure release and the methods would then be compared for accuracy and precision. The chemical release would be ethyl acetate with no person in the ventilation laboratory. The laboratory is positively pressurized, ventilated, and approved for such a scenario. TWA results would be compared to the CEMWIP calculations. The hypothesis is both personal monitoring approaches would provide comparable TWA data, however the PID would also provide instantaneous exposure levels at any given time. Continuous level monitoring while providing a TWA can also determined if the REL was ever exceeded during that time period. The goal is to produce a TWA that meets the REL for ethyl acetate while the same event would not meeting STEL or ceiling levels, this would demonstrate an advantage of real-time monitoring for measuring short but high levels of chemical exposure and where they occurred.


The CEMWIP system will be evaluated for its accuracy and precision in measuring VOC levels, worker position and exposure time. The personal monitor will be moved to fixed locations in a simulation work area in an experimental pattern determined by statistical design. A traditional exposure assessment method, like NIOSH method 1457, will be used for statistical comparison of the prototype's ability to measure time weighted average exposure assessments against currently acceptable methods. Data will be collected and analyzed for a simulated chemical release. The chemical monitor will be placed on manikins and no human subject will be exposed.