2

• 5 Reasons for Hygiene Assessment

  • Qualitative and Quantitative
  • Compliance or due diligence
  • Relate health effects with exposure
  • Determine effectiveness of controls
  • Obtain exposure information for health research or epidemiology studies
• Hygiene Survey

  • Process and material survey
  • Worker's job and health status survey
  • Walk-through survey
• Process and Material Survey

  SDS is quite helpful here

  Survey the production process of concern and materials being used Examine how and what materials are being used;

  Temperatures, transfer points, cutting, grinding and what engineering controls currently are in place.

  Examine initial, by-products, end products

  Includes assessment of raw materials, byproducts, finished products
• Workers Job and Health Survey

  The purpose here is to relate the workers to the actual potential exposure

  Recognition process of workers potential exposure

  Total number of workers?

  What their jobs are?

  What complaints have been expressed? (where do you get this info.?) Review of Workers Compensation claims?

  Base line medicals? Especially for designated substances!
• Recognition process of workers potential exposure

  Total number of workers?

  What their jobs are?

  What complaints have been expressed? (where do you get this info.?) Review of Workers Compensation claims?

  Base line medicals? Especially for designated substances!
• Walk Through Survey

  Walk through the process, identify workstations and observe control measures and work practices. See how everything interacts.

  Conducted usually with a worker rep and a management rep

  Relies on:

  Smell  Hear  See  Feel  Taste  Make Observations and Interview Employees
• Action Level = is equal to one half of the legal exposure limit  If the results are greater than or equal to the action level, then appropriate recommendations should be made
• 7 questions for sampling strategy:

  What should be sampled

  Why sample

  Where to sample

  Who should be sampled

  When to sample

  How long to sample

  How many samples
• What Should be Sampled?

  Determined by the first phase of the recognition process: Process and Material Survey. SDS is really helpful here. Things to consider:

  Toxicity of the agent

  The amount of agent being processed

  Likelihood it will become airborne

  Ontario Designated Substance Regulations

  Record Keeping as part of control program
• Why Sample?

  Compliance, Worker complaint, MLTSD Order, due diligence
• Where to Sample?

  2 Types: Area or Personal

  Area Samples

  • Information of exposure in an area—strategic locations e.g. respiratory level
  • Useful to identify/confirm the source of contamination  Helpful to check controls and control equipment
  • Area samples hooked into alarms e.g. garage
  • Determine which workers are most at risk
• Personal Samples

  • Provides information on the individual exposure
  • Place as close to breathing zone as possible
  • Make note of work practices
  • Type of process workers are involved in
• Who Should be Sampled?

  Sample workers who are at maximum risk

  Sample workers who work near by

  Sample workers who are remote from source, but have complained of symptoms
• Ontario Designated Substance Reg.

  • For workers who may be exposed to a designated substance, the employer must conduct a qualitative and quantitative assessment.
• How Long to Sample?

  Duration of Worker exposure

  The allowable exposure values  STEL  TWA  C 

  Sampling and analytical method characteristics
• How many samples must be taken?

  Depends on purpose of the sample

  • Controls—before and after implementation of controls. Need several samples
  • Regular exposure
  • 8 hour work day or a 40 hour week exposure—take enough to evaluate TWA usually at least 75% of the work shift
  • STEL take grab samples for peak worker exposure
  • Ceiling ---taken during worst case scenarios
• When Do We Sample?

  Build up in afternoon

  Different shifts depending on company

  Once-a-week process?

  Weather conditions (seasonal conditions)

  AC, heating or natural ventilation, humidity in air
• Calibration - To mark or compare an instrument with a standard scale

  OR,

  To make sure measurements made with an instrument are accurate
• Flow rate determines the sample volume when combined with sample time
• Type categories of calibration equipment

  • Primary standards
  • Secondary standards
• Primary Standards

  Flow rate measured based on internal dimensions alone

  Measure the time it takes a known volume of air to travel through an inverted buret
• Secondary Students

  Do not provide a direct measure of volume

  Rotameter

  • Pulls air through a tapered tube containing a float or ball
  • Flow rate is read off the height of the float or ball
  • **MUST** be calibrated with a primary standard
• Primary are more accurate

  Secondary are more rugged and suitable for field use
• How to Sample?

  Collection Technique, Instrumentation and Analytical Methods

  NIOSH’s Analytical Method Guidelines.

  Recognized and deemed reliable.

  OSHA Method

  Modified NIOSH or OSHA method therefore good idea to consult with the lab
• Instrumentation

  • What are the limitations of the instrument
  • What are the principles of detection of the instrument
  • Are the limitations and detection principles suitable for our needs
  • Is the instrument reliable, precise, accurate and sensitive to the agent being measured
  • Need to ensure instrument is pre and post calibrated. All records must be kept.
  • Need to ensure instrument is free from contaminants or at least note possible contaminants. - Ensure instrument is safe to use e.g. intrinsictly safe
•  Gas: A substance that is normally in a gaseous state under normal room temperature & Pressure - O2 , N2 CO2
• Vapour: Solid or liquid under normal room temperature and pressure conditions; example organic substances like ethanol & acetone.
• Consider 5 Points

  1. Duration of sample
  2. Collection techniques should ensure efficiency
  3. Target agent should remain stable during analysis
  4. Reliable and recognized procedure should be used
  5. Sampling procedures must be safe
• Process for Sampling Gases and Vapours

  1.Determine Sampling Technique

   Grab Sampling  Absorption  Adsorption

  2. Complete Sampling as outlined by NIOSH Analytical Method

  3. Send to laboratory for analysis

  4. Analysis Method will depend on NIOSH

  5. Close loop within workplace
• Absorption

  The gas or vapour is being absorbed into a liquid medium.  Uses a sampling pump to draw the gas/vapour in, to bubble through the liquid medium  Allows for intimate contact with the medium for efficient absorption  Important that other contaminants do not interfere with the collection process or the analysis.  Sampling rate must be controlled  Contact time must be sufficient  Evaporation of the medium must be controlled  Used mainly for area sampling because of bulkiness and potential for liquid to spill e.g. midget impinger
• Adsorption

   When a gas/vapour “stick” to a solid medium such as activated charcoal  Activated charcoal=charcoal that has been treated at the microscopic level  The surface is very fragmented, therefore total surface is large  Suction by the sampling pump will cause the molecules of the gas/vapour to flow through the activated charcoal and stick to the surface e.g. an activated charcoal sampling tube
• Grab Sampling - Involves the use of a container to collect the gases or vapour as is

  Disadvantage

   reaction with the gas or vapour with the walls of the container

   The surface of the container must be inert to the gas or vapour
• Direct Reading Instruments - Use a variety of chemical and physical properties to detect the presence and/or of an air contaminant on the spot
• Direct Reading Instruments

  Advantages:

  On the spot measurements

  Analysis is the laboratory is not required

  Built in data loggers
• Direct Reading Instruments

  Disadvantages:

   Expensive  Detect on a limited number of gases and vapours  Usually are designed for a class of chemicals (eg:flammable) can not pin point the identity of a specific toxic agent
• Particulates: Dust, smoke, fumes, mist
• Filtration ► P.M. are collected by filtering the air stream that is carrying the contaminants in a particulate form ► Uses a filter ► Need to know the pore size of the filter so that the particles can be trapped instead of passing through ► Proper filter material needs to be selected for analysis
• The inhalable mass fraction is the total mass of aerosol that can be expected to enter through the nose and mouth.

  The thoracic mass fraction is the amount that can penetrate the respiratory system past the larynx.

  The respirable mass is the amount capable of depositing within the lungs, particularly the gas exchange region.
• 3 Types of Particle Size

   Total = any size that is in the air that can be pulled onto the filter cassette  Inhalable = e.g. using the IOM sampler at 2 LPM more popular or the Button Sampler 4LPM not as popular

   Respirable = using a cyclone at 1.7 LPM
• Size Selective Sampling

   Uses the technique of fractioning out the total airborne particulate matters based on their particle size

   2 main techniques:

   Cyclone

  Centrifugal separator. Large particles go to the base, small particles are trapped on a filter. Respirable size particles can be collected.

   Impaction

  Changes the direction of the airflow. Larger particles can not change, results in impacting on a plate where they are collected.