Real-time Exposure Assessment Terri A. Pearce, Ph.D. Occupational Safety and Health Administration Oklahoma City Area Office

Real-Time Instantaneous – Absolute, Average, Rolling average Near real-time – Processor delay, lag for data transmission Adjusted – After data interpolation

Exposure Assessment Source – Contaminant – Route of Entry – Monitoring method efficacy Receptor – Proximity – Dose – Physiological construct

NIOSH DREAM Workshop

Six Monitoring Categories Noise Radiation Gases and Vapors Aerosols Ergonomics Biomonitoring and Surface Sampling

AIHA Survey 684 respondents (640 users) with most respondents from manufacturing and services sectors 546 reported using DRMs as supplements to laboratory analysis with 445 also using DRMs as alternatives to conventional methods Particle monitors used most often followed by gas and vapor monitors

Choosing a DRM Top is number of respondents Bottom is percent of total 1234 Comparability to standard assessment methods 255 (47%) 88 (16%) 91 (17%) 105 (19%) Cost 50 (9%) 120 (23%) 160 (30%) 203 (38%) Ease in accessing and interpreting data 168 (31%) 204 (38%) 106 (20%) 61 (11%) Portability 133 (23%) 175 (30%) 161 (28%) 108 (19%)

Future Needs More contaminant specific Multiple contaminants More user friendly Less cumbersome Less expensive Specific to unique hazards

Sampling strategies

Strategy development

Types of Monitoring Hazard zones Emission points Controls (pre- and post-implementation) Tasks (work practice) Exposure assessment

Hazard Zones Go/no go, safe/not safe Accuracy, precision, and bias not as important if error is on side of most conservative (protective) decision Established technology with good accessibility for workers

Emission Points Yes/no, high/low Process emissions versus leak detection May need to know background contaminant levels Sensitivity may not be as important as specificity

Controls Before/after Accuracy or bias may not be as important as precision May follow-up with area or personal monitoring

Tasks Tasks/overall TWA Process emissions versus work practice Accuracy, precision, and bias all important Comparability across monitors if evaluating more than one worker

Exposure Assessment Above/below OEL Accuracy, precision, and bias are important, specificity is good too Results consistent across time and concentration Comparability among monitors and with conventional method

Selecting a Method Understand mission/objective Regulatory requirements Capabilities of the technology Calibration status User friendliness AIHA Real Time Detection Systems Committee

Selection Logic Birch, M.E., T.A. Pearce, and C.C. Coffey: Direct-Reading Instruments for Gas and Vapor Detection (Publ. No. ASI18). American Conference of Governmental Industrial Hygienists (ACGIH): Cincinnati, OH, 2009.

Monitor Selection Active/Passive Size Weight Durability Alarms Display Intrinsic safety Price Ease of calibration/bump test Sensor availability AIHA Real Time Detection Systems Committee

Sensor Selection Compatibility with monitor Specificity for agent of interest Service life Price AIHA Real Time Detection Systems Committee

Noise Area versus personal sampling Continuous versus impulse noise Measurement mimics the physiological response

Personal Dosimeters Microphone placed in proximity to the ear Provides the cumulative exposure over the course of the exposure period Display allows for administrative control

Sound Level Meters Provides for identifying noise source and contributing frequency Better at measuring impulse noise

Applicability of Noise Monitor Yes – Hazard zones – Emission points – Controls pre- and post-implementation – Hazards associated with specific tasks – Exposure assessment

Radiation Area versus personal sampling Real-time and Near real-time Measurement equates to the physiological response

Area Survey Monitors Real-time counters – Geiger-Muller – Ion chamber – Proportional

Personal Dosimeters Real-time – Pocket dosimeter – Digital electronic dosimeter Audible alarm rate meter Near real-time – Film badges – Thermoluminescent dosimeters

Applicability of Radiation Monitor Yes – Hazard zones – Emission points – Controls pre- and post-implementation – Hazards associated with specific tasks – Exposure assessment

Gases and Vapors Area versus personal sampling Single versus multiple gases Not a direct measure of physiological effect

Single gas monitors Mercury Specific Sensors – carbon monoxide, chlorine, chlorine dioxide, hydrogen cyanide, hydrogen sulfide, nitrogen dioxide, phosphine and sulfur dioxide

Multi-gas monitors Configured with multiple sensors Capable of detecting properties of individual gases – Photoionization – Flame ionization – Infrared – Gas chromatography – Mass spectrometry

4-gas Monitors Confined Space Regulation – Oxygen deficiency – Combustible gases and vapors (LEL) – Toxics Carbon Monoxide Hydrogen Sulfide

Applicability of Gas/Vapor Monitor Yes – Hot zones versus safe zones Maybe – Emission points – Controls pre- and post-implementation – Hazards associated with specific tasks No – Exposure assessment

Aerosols No monitor is particle specific Measure in mass or particle count/volume of air Not a direct measure of physiological effect

Mass monitors Area versus personal May have integrated filter for subsequent analysis

Particle counters Area monitors only Total versus size differentiating Coincidence errors at high concentrations

Applicability of Aerosol Monitor Maybe – Hot zones versus safe zones – Emission points – Controls pre- and post-implementation – Hazards associated with specific tasks No – Exposure assessment

Respirator Fit-testing Aerosol monitor used to determine appropriateness of personal protection

Ergonomics NIOSH lifting equation Capabilities for measuring force strength on actual muscles

Biomonitoring Personal sampling only Parameter measured is or approximates the physiological response

Surface Sampling Area versus personal sampling Connections to physiological response may be possible

Terri A. Pearce, Ph.D. Oklahoma City Area Office 55 N. Robinson, Suite 315 Oklahoma City, OK