Air Monitoring

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Information about Air Monitoring

Published on October 23, 2007

Author: WoodRock


Practical Considerations For Air Monitoring With Emphasis On Direct Reading Real Time Monitors:  Practical Considerations For Air Monitoring With Emphasis On Direct Reading Real Time Monitors Occupational Hygiene Association of Ontario Spring Symposium By: Jamie Prince B.Sc, OHST, ROHT General Motors of Canada Limited OUTLINE:  OUTLINE What Can Be Measured Sampling Strategies Types of Sampling Equipment Examples of Real Time Monitors Advantages/Disadvantages of Real Time Air Monitoring Real Time Air Monitoring Examples Conclusions PHYSICAL/CHEMICAL STATES:  PHYSICAL/CHEMICAL STATES solids: dust, fibres, fume, smoke liquids: mist, aerosols gases: vapours remember: gas solid liquid 7 TYPES OF CONTAMINANTS:  7 TYPES OF CONTAMINANTS Dusts- airborne solid particles ranging in size from 0.1 to 25 microns. Particles 5 microns and larger don’t usually remain airborne to present an inhalation hazard. Fumes- material from a volatized solid condenses in cool air. Size of the particulate formed are less than 1 micron in diameter. Smoke- from incomplete combustion of carbon containing materials, its made up of carbon or soot particles. Can vary in size. 7 TYPES OF CONTAMINANTS :  7 TYPES OF CONTAMINANTS Aerosols- liquid droplets or solid particles, fine enough to remain dispersed in air for a prolonged period. Mists- liquid droplets suspended in the atmosphere. Gases- are “formless fluids” that expand to fill the space or enclosure in which they are confined. Vapours- are the volatile form of substances that are usually in the liquid or solid state at room temperature and pressure. PHYSICAL/CHEMICAL STATES:  PHYSICAL/CHEMICAL STATES size: respirable (less than 10 μm) fibres (length & diameter) chemical charge (CrIII or CrVI) solubility (Ni) crystal structure (silica, talc) fibrous or non-fibrous polar/non polar MIXTURES:  MIXTURES decomposition products (smoke, etc.) often have thousands of components sometimes “marker” substances measured (like CO) if a “marker” is used, the TWAEV for the marker substance is not applicable! can be sampled as a group (e.g. VOC’s), but usually no TWAEV MIXTURES:  MIXTURES Measuring each of the thousands of constituents in decomposition products would be a chemist’s nightmare almost all of the constituents will be well below individual TWAEV’s even summing the TWAEV’s seldom exceeds summed TWAEV criteria Combinations: Vapour condensing on particles vapour absorbed by liquid aerosols liquid evaporating from aerosol/particulate SO YOU WANT TO SAMPLE?:  SO YOU WANT TO SAMPLE? Then answer the 5 W’s and 3 H’s: Why? What? Who? When? Where? How? How many? How long? SAMPLING STRATEGIES WHY?:  SAMPLING STRATEGIES WHY? Reactive Sampling, Source Identification -Employee Concerns: What’s causing the complaints/symptoms Compliance Sampling, New Process, DSR Proactive Sampling Engineering Control Verification ALTERNATIVES TO SAMPLING:  ALTERNATIVES TO SAMPLING Eliminate the source Add engineering controls Use odour and irritation thresholds Hazard mapping, use employee experiences Computer modelling EXPOSURE CONTINUUM :  EXPOSURE CONTINUUM source > path > exposure > uptake > target Try to move as far to the left of the continuum as possible (prevention!) Source: substitution, enclosure Path: ventilation evaluation, work practices Exposure: IH measurements Uptake: symptoms, blood/urine samples Target: clinical tests, diagnosis SAMPLING STRATEGIES WHAT?:  SAMPLING STRATEGIES WHAT? Type: bulk, area, personal Time: short term (CEV, STEV), long term (TWAEV), sequential, grab (series) Method: “quick and dirty” (colourimetric), direct reading real time, official (NIOSH etc) Conditions: worst case, random (unbiased), staged (simulated), regular work shift. Number: “one shot”, statistically representative, cumulative exposures WHO WHEN WHERE?:  WHO WHEN WHERE? What workplace variables cause exposures to go up or down? weather (season, temp, humidity, wind) doors & windows, cross drafts shift, production schedules, rates ventilation in other areas of plant housekeeping, traffic, activity levels individual work practices, man cooling fans SAMPLING CONDITIONS:  SAMPLING CONDITIONS make sure important variables are addressed in strategy keep records of conditions during sampling start & finish times production levels ventilation (doors, windows, local & general) workers’ opinion if sampling period is representative of better than average, normal, worse than normal conditions HOW? TYPES OF SAMPLING EQUIPMENT:  HOW? TYPES OF SAMPLING EQUIPMENT Colourimetric (Draeger tubes, dositubes) Passive Absorption Badges: Organic Vapours, formaldehyde, other gases and vapours Pumps: filter cassettes (with or without cyclones or impacters) for particulates, aerosols and fibers sorbent tubes, (charcoal, silica gel, specialized) for gases and vapours. Liquid samplers (impingers) for vapours, particulates, aerosols TYPES OF REAL TIME AIR MONITORS:  TYPES OF REAL TIME AIR MONITORS Particulates Total particulates/aerosols (data-logging): DataRam, Dust Trak Fibers: FAM (Fibrous Aerosol Monitor) asbestos Gases/Vapours FID and PID (data-logging) for organic compounds Inorganic gases and vapours, CO, CO2, mercury, H2S Paper Tape for isocyanates Lead Niton X-ray fluorescence Indoor Air Quality multi-function monitors HOW MANY?:  HOW MANY? How Many Samples Do You Need To Take? Compliance sampling needs a large number of representative samples over a long period of time use traditional sampling methods Worst case sampling may require only a few samples over a short period direct reading or real time may be required Type of hazard may determine how many and for how long peak exposures, length of peaks, short term acute hazards, does it come and go HOW LONG?:  HOW LONG? Lowest detectable quantity Don’t overload sample media Short sample period for acute hazards Chronic hazard may need full shift Peaks need data-logging, real time direct reading or short term sequential samples IDLH for confined space needs immediate answer Leak detection needs direct reading DISADVANTAGES OF LONG TERM SAMPLING :  DISADVANTAGES OF LONG TERM SAMPLING Analysis and Feedback time too long, chance of exposing employees to hazardous levels Inability to answer employee concerns, continued refusal to work, loss of production Inability to Determine STEL and Ceiling Values, ie. short term maintenance jobs 90% of all long term samples were less than 10% of any EEG, however employees continued to complain, especially of irritation Ineffective use of Hygienist’s time ADVANTAGES OF REAL TIME:  ADVANTAGES OF REAL TIME Instant feedback of exposure levels to hygienist and employees, ease of mind Employee trust, can see exposure on meter Ability to determine time vs concentration with data-logging instruments Ability to determine STEL and Ceiling Values Quick determination of how changes to process or engineering controls affect employee exposures More efficient use of hygienist’s time DISADVANTAGES OF REAL TIME AIR MONITORS:  DISADVANTAGES OF REAL TIME AIR MONITORS Specificity of monitor Interpretation of results, employee misunderstanding Interferences, CO, TOHC’s , Water Vapour Method may not be accepted by Government Difficult or unable to Calibrate Assuming dust monitor detects all particle sizes equally well Cannot usually be used for compliance sampling, lead, isocyanates, silica, asbestos Accuracy REAL TIME INSTRUMENTS:  REAL TIME INSTRUMENTS CENTURY SYSTEMS OVA TOHC RIKIN 411 CO2 MONITOR DRAEGER CO DATALOGGER MINIRAM, TP DATARAM TP DATALOGGER REUTER STOKES WIBGET GMD AUTOSTEP (CAP) ISOCYANATES TOXIRAE PID TOHC’S SOLOMAT IAQ MONITOR SEALER REMOVAL SOLVENT:  SEALER REMOVAL SOLVENT INSTRUMENT- CENTURY SYSTEMS OVA Sealer removal from car in open area which solvent had lowest exposure levels FP and VP not useful solvent 1- 35-40 ppm peaks TWA 100 ppm solvent 2--50-60 ppm peaks TWA 100 ppm solvent 3--35-40 ppm peaks TWA 100 ppm solvent 4--20-30 ppm peaks TWA 100 ppm solvent 5---85-100 ppm peaks TWA 400 ppm Solvent 4 or 5 recommended Solvent 4 chosen because of higher FP FLAT TOP CO:  FLAT TOP CO INSTRUMENT- DRAEGER CO DATALOGGER CO buildup suspected for new driving and parking procedures on flat top conveyor CO levels data-logged in various areas ventilation on and off CO levels data-logged while different procedures were used for idling cars while parked Determined that new procedures did increase CO to hazardous levels in one area. Immediate ventilation system changes reduced maximum CO levels to non hazardous levels COAST CLUTCH BLOWOFF:  COAST CLUTCH BLOWOFF INSTRUMENT-DATARAM AEROSOL MONITOR Using compressed air to blow off and clean Transmission parts. Does ventilated box and lower air pressure reduce exposures. Total particulates data-logged while blowing off parts in general work area TP’s data-logged with part held in ventilated box Determined box increased exposures since exhaust in box too low, and blow back Lower air pressure decreased exposures BLACK PRIME:  BLACK PRIME INSTRUMENT-CENTURY SYSTEMS OVA Black prime with MEK applied to window openings on ventilated ramp, employees complain of irritation and odours How did casablanca fan speed and application method affect exposures MEK levels taken in BZ and general area with fans on high 3X higher than fans on low MEK peak levels taken In BZ while leaning over applied prime 4X higher than when furthest part of window was primed first Set fans to low speed, disabled rheostats Rec’d not to lean over applied prime PAINT SPRAYING:  PAINT SPRAYING INSTRUMENT- CENTURY SYSTEMS OVA Employees paint spraying rear of vehicle Long term test showed paint solvent exposures <5 ppm, but employees continued to complain of irritation and odours sampled BZ while spraying across from each other, found peaks of 200 ppm TOHC from overspray sampled BZ while staggering their spraying, found peaks below 10 ppm Recommended that paint sprayers in all booths stagger their paint spraying METAL WORKING FLUIDS:  METAL WORKING FLUIDS INSTRUMENT- MINIRAM AEROSOL MONITOR Employees working on machining line complaining of irritation, all equipment ventilated Miniram used to survey BZ and general work area Levels in area rose slowly as machining progressed followed plume of mist back to one faulty filter after filter repaired, levels remained low Recommended preventative maintenance on filters of ventilation equipment METAL WORKING FLUIDS:  METAL WORKING FLUIDS INSTRUMENT(S)- DATARAM AEROSOL MONITOR & TSI DUSTRAC Total Particulate Levels Required to Determine Need For Engineering Controls Total Particulate Mapping of Component Manufacturing Plants on a 6mX 6m Grid. Results plotted on an Excel Spreadsheet. Chart of Exposure Levels (Contour) Printed on Overhead. Contour Chart Overlaid on Plant Layout. Areas of Higher Exposure Targeted for Improvement Engineering Controls installed Plant is Remapped to Determine Improvement Conclusions:  Conclusions Is sampling necessary, can the problem be solved another way? Ensure your sampling strategy is right. Real time air monitoring benefits include: ability to determine patterns of exposure ability to quickly evaluate engineering or process control changes reasonably determine potential of exposure to cause adverse health effects dollar savings from reduction of lab analysis and hygienist’s time being used more effectively

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