1. 1 Air Monitoring: Back to Basics

2. 2 Air monitoring is commonly performed on Hazardous Waste Operations (HazWoper) sites There is more to air monitoring than “waving a wand” You need a strategy in order to have meaningful results Air monitoring is a generic term – often used for both air monitoring & air sampling The focus today is on air monitoring – however both may be needed for your project! Overview

3. 3 Monitoring vs. Sampling Air Monitoring Direct reading instruments, “real time” data Compared against action levels Typically hand-held Usually performed for short duration Typically performed by URS field crew – Site Health and Safety Officer Air Sampling Collects air sample, analyzed by lab Compared against PELs, STELs or Ceiling Limits Personal sampling pump & collection media Usually collected over 8 hour shift Typically performed by Industrial Hygienist or other specially trained individual

4. 4 Air Monitoring 29 CFR 1910.120 states: “Air monitoring shall be used to identify and quantify airborne levels of hazardous substances in order to determine the appropriate level of employee protection needed on site”

5. 5 Key Elements of a Monitoring Plan Define site activities and discrete tasks Identify potential airborne hazards for each task (metals, hydrocarbons, CO, H 2 S, etc.) Identify who should be monitored Establish air monitoring objectives Select equipment Interpret data

6. 6 Defining Activities & Tasks Review project documents such as the project proposal, contract, scope of work, and/or specifications, & responsibilities Discuss field activities with Project Manager & field staff Develop detailed job safety analysis Identify who will perform the task and the approximate time needed to complete the task Field activities and tasks must be clearly defined. How to define field tasks?

7. 7 Identifying Potential Hazards The most common atmospheric hazards include: Toxic substances (gases, vapors, particulates) Oxygen deficient (<19.5% O 2 ) Flammable (gases, vapors, particulate, or oxygen enriched)

8. 8 Identifying Potential Hazards Also consider : The volatility of site contaminants (methylene chloride vs. creosote) and outside temperature Products used on site (paints, cleaners, welding supplies, sample preservatives) Materials removed or disturbed on site (lead paint, asbestos insulation, etc.)

9. 9 Scenario #1 Answer: Not likely, because: No expected contaminants Work performed in the open No intrusive activities “Up-gradient well” indicates good knowledge of the site. A URS field team will be collecting groundwater samples from established, up-gradient monitoring wells. Is air monitoring needed?

10. 10 Scenario #2 URS is contracted to excavate and remove buried drums containing pesticide waste. Subcontractors will operate excavation equipment and haul waste off-site. New housing developments and a grade school borders the site. Is air monitoring needed? Answer: Absolutely! And the monitoring program will likely be complex and costly.

11. 11 Identifying Who Should be Monitored Monitoring is likely needed for workers who are: Closest to the “source” of contamination Performing tasks that generate airborne contaminants (painting, welding, sand blasting, etc.) Entering confined spaces

12. 12 Scenario #3 A team is contracted to install ground water monitoring wells down gradient from a former retail gas station. A drilling subcontractor will install the wells. Who should be monitored? Answer: It is often responsible for the drilling crew. The breathing zone of the drillers helper would be the best location for monitoring.

13. 13 Common Monitoring Objectives Assess worker exposures to airborne contaminants Establish level of respiratory protection Evaluate fire/explosion hazards Evaluate effectiveness of engineering controls Evaluate off-site migration of airborne contaminants Remember – certain regulatory standards (e.g. asbestos) mandate air sampling.

14. 14 Most commonly used for: Flammable or explosive atmospheres Oxygen deficiency Volatile organics Nuisance dusts Radiation Direct Reading Instruments

15. 15 Direct Reading Instruments Advantages Readings displayed quickly (within seconds) Durable Portable Easy to use Disadvantages Often not specific May have limited detection range Cross-sensitivity Can be temperature & moisture sensitive Can’t be used for most metals, asbestos, silica or unknowns

16. 16 What is the most important thing in gas detection when using Direct-reading instruments? Proper Calibration! Without a clean zero gas and an accurate verified calibration standard - there is no point in doing any gas detection. Calibration

17. 17 Calibration Calibrate per manufacturer recommendations Check calibration in field every day Record calibration results & keep in project file

18. 18 Photoionization Detectors - (PIDs) Uses ultraviolet light to ionize molecule. Primarily used for organic vapors (particularly BTEX) - certain instruments use a benzene chip Ionization potential (IP) of lamp must exceed IP of molecule Lamps typically range from 9.5 eV to 11.7 eV Response is relative to the response of the calibration gas Limitations include:  Cross sensitivities,  Lack of specificity when multiple compounds are present,  Impacted by high humidity Key manufacturers include: HNU, Photovac, RAE Systems, MSA

19. 19 Flame Ionization Detectors - (FIDs) Uses hydrogen flame to ionize molecules Ionization range is higher than PID Response is relative to the concentration of the calibration gas Limitations include:  Shipping hydrogen gas  More complex operation than PIDs  Sensitive to methane Manufacturers include:  Foxboro, Photovac

20. 20 Combustible Gas Indicators - (CGIs) Normally combine % oxygen and % Lower Explosive Limit (LEL) in one monitoring device LEL sensor requires adequate oxygen; always check oxygen first Measures “percent of” the LEL LELs typically range from 0.8 to 6% Action level of 10% to 25% of LEL to evacuate/stop work Remember to use intrinsically safe instruments in flammable atmospheres.

21. 21 Oxygen Meters This test is conducted first since it may affect the accuracy of other meters/sensors Sensors have a shelf life of 1-2 years Acid gases or high CO 2 may poison the sensor and shorten the instrument life

22. 22 Oxygen Meters Oxygen deficient atmospheres are the #1 cause of confined space fatalities.  Oxygen enriched> 23.5% O 2  Normal atmosphere 20.8% O 2  Oxygen deficient< 19.5% O 2  IDLH*< 16.0% O 2 * Immediately Dangerous to Life and Health

23. 23 Colorimetric Detector Tubes Pump draws air through chemically treated tubes. The contaminant reacts with the chemical indicator to produce a color change or stain.

24. 24 Colorimetric Detector Tubes Accuracy of ± 25% Limitations include:  Cross sensitivities  Temperature extremes  Difficulty in determining stain length  Short duration sample time Check pump for leaks prior to use with an unbroken tube Carefully read the directions for the specific tube you are using (e.g. number of pump strokes, color change, flow direction)

25. 25 Aerosol (Dust) Monitors Uses light scattering to measure concentrations of particulates Reads out in mg/m 3 Not specific - measures total dust or respirable dust, depending on the unit

26. 26 Other Direct Reading Instruments Hydrogen sulfide meter Carbon monoxide meter (H 2 S & CO are usually part of 4 way meter) Mercury vapor analyzer Radiation detectors Portable gas chromatograph Ammonia detector

27. 27 Interpreting the Data (What does it all mean?) Direct reading instruments are essential field equipment Displays are generally easy to read and appear to be very precise But, the data is meaningless unless there is an action level that was developed based on the chemicals of concern and the equipment response. Do not confuse soil/water concentrations of the contaminants with airborne concentrations and action levels.

28. 28 Action Levels Action Levels are threshold readings on a direct reading instrument that, if exceeded, require an action (such as upgrading PPE or evacuation) Documented in Project Health and Safety Plans and are based on:  Chemicals of concern  Exposure limits (such as PELs & TLVs)  Type of instrument  Relative response

29. 29 Action Levels Action levels should be: Simple, clear & real-time Based on compound with lowest exposure limit (when dealing with multiple compounds) Less than exposure limit to compensate for instrument accuracy (safety margin) Based on instrument that will measure chemicals of concern in range of exposure limits

30. 30 Action Levels - Example Table

31. 31 Important Terms Sensitivity – Ability of an instrument to detect the material in the range of interest. Accuracy – How close the instrument readout is to the actual concentration. Relative Response – Instrument response to a chemical of concern relative to the response to the calibration gas.

32. 32 Important Terms Parts per million (ppm) – Parts per million by volume in air; primarily used for gases and vapors. Examples of OSHA PELs:  Phosgene = 0.1 ppm  Hydrogen sulfide = 20 ppm  Toluene = 200 ppm 100%=1,000,000 ppm 1%=10,000 ppm.01%=100 ppm.0001%=1 ppm

33. 33 Important Terms Milligrams per cubic meter (mg/m 3 ) – Milligrams of contaminant per cubic meter of air; used for particulates, dusts, mists and fumes. 1 mg/m 3 = 1000 µg/m 3.1 mg/m 3 = 100 µg/m 3 Examples of OSHA PELs:  Arsenic = 0.01 mg/m 3 or 10 µg/m 3  Lead = 0.05 mg/m 3 or 50 µg/m 3  Nuisance dust = 15 mg/m 3 or 15,000 µg/m 3

34. 34 Understanding the Data - Some Guidelines “Zero” does not necessarily mean “clean”. Possible reasons for “zero” readings:  Instrument is not working  Concentration of compound is below the detection limit (sensitivity)  Instrument responds poorly (or not at all) to the compound of interest  Compound of interest is not volatile  The area is actually “clean”

35. 35 Understanding the Data - Some Guidelines Readings displayed may not be the actual concentration. Possible reasons include:  Relative response - Instruments rarely have a 1:1 response to a particular compound. Check user manual for response factors.  Multiple compounds - instrument may be picking up a variety of compounds, each with it own response factor or there may be an interference.  Response time - instruments may take several seconds to respond. If survey is too quick - may not pick up “hot spots”.  Instrument specificity - no single instrument can detect all airborne contaminants. Check user manual for specificity.

36. 36 Reading may not indicate actual exposure risk. Possible reasons include:  Other routes of exposure - such as dermal exposure (particularly heavy organics such as creosote, PCBs, and some pesticides).  Reading not taken in worker breathing zone - actual risk may be higher or lower depending on where reading is taken.  Multiple contaminants - possible additive or synergistic effects.  Individual sensitivity - exposure effects can vary greatly from person to person. Understanding the Data - Some Guidelines

37. 37 Recording the Data Record data in field log book or other suitable form. Download or print out data if possible. Record calibration checks and “zero” readings. Maintain records on site while project is active; place in project file when project is finished. Can’t prove the monitoring was conducted unless the data is recorded and retrievable.

38. 38 Review Scenarios 1.You’re the PM on a job involving the cleaning and dismantling of above ground gasoline storage tanks. You have a plan and equipment for monitoring organic vapors. OSHA arrives and requests to see your exposure control plan and air sampling data for Lead (tanks were painted with lead based paint - oops). What went wrong?

39. 39 Review Scenarios 2.You’re the PM on a job involving the excavation and removal of soils impacted with BTEX compounds. You have a plan and equipment for monitoring organic vapors. Employees are complaining of strong odors, getting headaches, and feeling sick but the PID is reading below the action level. What’s going on?

40. 40 Review Scenarios 3.You’re preparing a proposal for the excavation and removal of hundreds of drums of pesticide residue buried in an old, industrial landfill. What considerations do you need to make for air monitoring? Who do you go to for help?