Wednesday, January 26, 2011

Occupational Hygiene


Occupational (or "Industrial" in the U.S.) hygiene is generally defined as the art and science dedicated to the Anticipation, Recognition, Evaluation, Communication and Control of environmental stressors in, or arising from, the work place that may result in injury, illness, impairment, or affect the well being of workers and members of the community. These stressors are divided into the categories Biological, Chemical, physical, Ergonomic and Psychosocial. The British Occupational Hygiene Society (BOHS) define that "Occupational Hygiene is about the prevention of ill-health from work, through recognizing, evaluating and controlling the risks".  The International Occupational Hygiene Association (IOHA) refers to Occupational Hygiene as the discipline of anticipating, recognizing, evaluating and controlling health hazards in the working environment with the objective of protecting worker health and well-being and safeguarding the community at large.
The term Occupational Hygiene (used in the UK and Commonwealth Countries as well as much of Europe) is synonymous with Industrial Hygiene (used in the US, Latin America, and other countries that received initial technical support or training from US sources). The term "Industrial Hygiene" traditionally stems from industries with construction, mining or manufacturing and "Occupational Hygiene" refers to all types of industry such as those listed for "industrial hygiene" as well as financial and support services industries and refers to "Work", "Workplace" and "Place of Work" in general. Environmental Hygiene addresses similar issues to Occupational Hygiene, but is likely to be about broad industry or broad issues effecting the local community, broader society, region or country.
The profession of Occupational Hygiene uses strict and rigorous scientific methodology and often requires professional experience in determining the potential for hazard, exposures or risk in workplace and environmental studies. This aspect of Occupational Hygiene is often referred to as the 'Art' of Occupational Hygiene and is used in a similar sense to the 'art' of medicine. In fact "Occupational Hygiene" is both an aspect of preventative medicine, in that its goal is to prevent industrial disease, and Risk Management, Risk assessment and industrial safety, in that it also seeks 'safe' systems, procedures or methods to be applied in the workplace or to the environment.
The Social Role of Occupational Hygiene
Occupational Hygienists have been involved historically with changing the perception of society about the nature and extent of hazards in the workplace. Many Occupational Hygienists work day to day with industrial situations that require control or improvement to the workplace situation however larger social issues affecting whole industries have occurred in the past e.g. since 1900, asbestos exposures that have affected the lives of tens of thousands of people.
More recent issues affecting broader society are, for example in 1976, legionnaires Disease or Legionellosis. More recently again in the 1990s Radon and in the 2000s the effects of mould from indoor air quality situations in the home and at work. In the later part of the 2000s concern has been raised about the health effects of nanoparticles.
Many of these issues have required the coordination over a number of years of a number of medical and para professionals in detecting and then characterizing the nature of the issue, both in terms of the hazard and in terms of the risk to the workplace and ultimately to society. This has involved Occupational Hygienists in research, collection of data and to develop suitable and satisfactory control methodologies.
Workplace Assessment Methods
Although there are many aspects to Occupational Hygiene work the most known and sought after is in determining or estimating potential or actual exposures to hazards. Several methods can be applied in assessing the workplace or environment for exposure to a known or suspected hazard. Occupational Hygienists do not rely on the accuracy of the equipment or method used but in knowing with certainty and precision the limits of the equipment or method being used and the error or variance given by using that particular equipment or method.
Walk Through Survey
A traditional method applied by Occupational Hygienists to initially survey a workplace or environment is used to determine both the types and possible exposures from hazards (e.g. noise, chemicals, radiation). The Walk Through Survey can be targeted or limited to particular hazards such as silica dust, or noise, to focus attention on control of those hazards. Frequently a full walk through surveys is used to provide information on establishing a frame work for future investigations, prioritizing hazards, determining the requirements for measurement and establishing some immediate control of potential exposures.

Electronic Hazard Survey Equipment

An Occupational Hygienist may use one or a number of commercially available electronic measuring devices to measure noise, vibration, ionizing and non-ionizing radiation, dust, solvents, gases, et cetera. Each device is often specifically designed to measure a specific or particular type of contaminate. Often such devices are subject to multiple interferences. Electronic devices need to be calibrated before and after use to ensure the accuracy of the measurements taken and often require a system of certifying the Precision of the instrument

Dust Sampling

Nuisance dust is considered to be the total dust in air including Inhalable and Respirable fractions.
Various dust sampling methods exist that are internationally recognised. Inhalable dust is determined using the modern equivalent of the Institute of Occupational Medicine (IOM) MRE 113A monitor (See section on Workplace exposure, measurement & modelling). Inhalable dust is considered to be dust of less than 100 micrometers Aerodynamic Equivalent Diameter (AED) that enters through the nose and or mouth. See Lungs
Respirable dust is sampled using a 'cyclone' dust sampler design to sample for a specific fraction of dust AED at a set flow rate. The respirable dust fraction is dust that enters the 'deep lung' and is considered to be less that 10 micrometers AED.
Nuisance, Inhalable and Respirable dust fractions are all sampled using a constant volumetric pump for a specific sampling period. By knowing the mass of the sample collected and the volume of air sampled a concentration for the fraction sampled can be given in milligrams (mg) per metre cubed (m3). From such samples the amount of Inhalable or Respiable dust can be determined and compared to the relevant Occupational exposure limits.
By use of Inhalable, respirable or other suitable sampler (7 hole, 5 hole, et cetera) these dust sampling methods can also used to determine metal exposure in the air. This requires collection of the sample on a Methyl-Cellulose Ester (MCE) filter and acid digestion of the collection media in the laboratory followed by measuring metal concentration though an Atomic Absorption (or Emission) Spectrophotometery. Both the UK HSE  and NIOSH NMAM have specific methodologies for a broad range of metals in air found in industrial processing (smelting, foundries, et cetera).
A further method exists for the determination of asbestos, fibreglass, synthetic mineral fibre and ceramic mineral fibre dust in air. This is the Membrane Filter Method (MFM) and requires the collection of the dust on a grided filter for estimation of exposure by the counting of 'conforming' fibres in 100 fields through a microscope. Results are quantified on the basis of number of fibres per millilitre of air (f/ml). Many countries strictly regulate the methodology applied to the MFM

Chemical Sampling

Two types of chemically absorbent tubes are used to sample for a wide range of chemical substances. Traditionally a chemical absorbent 'tube' (a glass or stainless steel tube of between 2 and 10 mm internal diameter) filled with very fine absorbent silica (hydophylic) or carbon, such as coconut charcoal (lypophylic), is used in a sampling line where air is drawn through the absorbent material for between 4 hours (minimum workplace sample) to 24 hours (environmental sample) period. The hydrophylic material readily absorbs water soluble chemical and the lypophylic material absorbs non water soluble materials. The absorbent material is then chemically or physically extracted and measurements performed using various Gas Chromatograph or Mass Spectometry methods. These absorbent tube methods have the advantage of being usable for a wide range of potential contaminates. However, they are relatively expensive methods, time consuming and require significant expertise in sampling and chemical analysis. A frequent complaint of workers is in having to wear the sampling pump (up to 1 kg) for several days of work to provide adequate data for the required statistical certainty determination of the exposure.
In the last few decades advances have being made in 'passive' badge technology. These samplers can now be purchased to measure one chemical (e.g. formaldehyde) or a chemical type (e.g. ketones) or a broad spectrum of chemicals (e.g. solvents). They are relatively easy to set up and use. However, considerable cost can still be incurred in analysis of the 'badge'. They weigh 20 to 30 grams and workers do not complain about their presence. Unfortunately 'badges' may not exist for all types of workplace sampling that may be required and the charcoal or silica method may sometimes have to be applied.
From the sampling method results are expressed in milligrams per cubic meter (mg/m3) or Parts Per Million (PPM) and compared to the relevant Occupational exposure limits.
It is a critical part of the exposure determination that the method of sampling for the specific contaminate exposure is directly linked to the exposure standard used. Many countries regulate both the exposure standard, the method used to determine the exposure and the methods to be used for chemical or other analysis of the samples collected
Example of Occupational Hygiene
  • See the Related Journals listed above for many examples of the science underlying occupational hygiene and its practical application
  • Analysis of occupational hygiene effects can lead to worker protection plans. For example it is common in high noise environments to use earplugs or earmuffs. These are available over a range of applications, effectiveness and quality.
  • Occupational Hygienists are among the experts planning the controls to protect against exposure in the event of a flu pandemic.
  • Occupational/Industrial Hygienists are responsible for monitoring and testing the air for hazardous contaminants that can lead to potential worker illness and sometimes death.

International Organization for Standardization
The following is a list of reference material available internationally from the ISO. There may also be significant material available at National, State or local level.
ISO 9000 Quality management (set): ISO 9000:2005 Quality management systems — Fundamentals and vocabulary ISO 9001:2008 Quality management systems — Requirements ISO 9001:2008 / Cor 1:2009 Technical Corrigendum 1:2009 to ISO 9001:2008 ISO 9004:2000 Quality management systems — Guidelines for performance improvements ISO 10001:2007 Quality management — Customer satisfaction — Guidelines for codes of conduct for organizations ISO 10002:2004 Quality management — Customer satisfaction — Guidelines for complaints handling in organizations ISO 10003:2007 Quality management — Customer satisfaction — Guidelines for dispute resolution external to organizations ISO 10005:2005 Quality management systems — Guidelines for quality plans ISO 10006:2003 Quality management systems — Guidelines for quality management in projects ISO 10007:2003 Quality management systems — Guidelines for configuration management ISO 10012:2003 Measurement management systems — Requirements for measurement processes and measuring equipment ISO/TR 10013:2001 Guidelines for quality management system documentation ISO 10014:2006 Quality management — Guidelines for realizing financial and economic benefits ISO 10014:2006 / Cor. 1:2007 Technical Corrigendum 1 to ISO 10014:2006 ISO 10015:1999 Quality management — Guidelines for training ISO/TR 10017:2003 Guidance on statistical techniques for ISO 9001:2000 ISO 10019:2005 Guidelines for the selection of quality management system consultants and use of their services ISO 19011:2002 Guidelines for quality and/or environmental management systems auditing
ISO 14000 Environmental Management (Set): ISO Guide 64:1997 Guide for the inclusion of environmental aspects in product standards ISO 14001:2004 Environmental management systems — Requirements with guidance for use ISO 14004:2004 Environmental management systems — General guidelines on principles, systems and support techniques ISO 14015:2001 Environmental management — Environmental assessment of sites and organizations (EASO) ISO 14020:2000 Environmental labels and declarations — General principles ISO 14021:1999 Environmental labels and declarations — Self-declared environmental claims (Type II environmental labeling) ISO 14024:1999 Environmental labels and declarations — Type I environmental labeling — Principles and procedures ISO 14025:2006 Environmental labels and declarations — Type III environmental declarations ISO 14031:1999 Environmental management — Environmental performance evaluation — Guidelines ISO/TR 14032:1999 Environmental management — Examples of environmental performance evaluation (EPE) ISO 14040:2006 Environmental management — Life cycle assessment — Principles and framework ISO 14044:2006 Environmental management — Life cycle assessment — Requirements and guidelines ISO/TR 14047:2003 Environmental management — Life cycle impact assessment — Examples of application of ISO 14042 ISO/TR 14048:2002 Environmental management — Life cycle assessment — Data documentation format ISO/TR 14049:2000 Environmental management — Life cycle assessment — Examples of application of ISO 14041 to goal and scope definition and inventory analysis ISO 14050:2002 Environmental management — Vocabulary ISO/TR 14062:2002 Environmental management — Integrating environmental aspects into product design and development ISO 14063:2006 Environmental management — Environmental communication — Guidelines and examples ISO 14064-1:2006 Greenhouse gases — Part 1: Specification with guidance at the organization level for quantification and reporting of greenhouse gas emissions and removals ISO 14064-2:2006 Greenhouse gases — Part 2: Specification with guidance at the project level for quantification, monitoring and reporting of greenhouse gas emission reductions or removal enhancements ISO 14064-3:2006 Greenhouse gases — Part 3: Specification with guidance for the validation and verification of greenhouse gas assertions ISO 14065:2007 Greenhouse gases — Requirements for greenhouse gas validation and verification bodies for use in accreditation or other forms of recognition ISO 19011:2002 Guidelines for quality and/or environmental management systems auditing ISO/IEC 17025:2005 General requirements for the competence of testing and calibration laboratories
ISO 31000:2009 Risk management – Principles and guidelines, ISO Guide 73:2009 Risk management—Vocabulary, ISO/IEC 31010:2009 Risk management—Risk assessment techniques.
ISO 15743:2008 Ergonomics of the thermal environment—Cold workplaces—Risk assessment and management
ISO/IEC 16085:2006 Systems and software engineering—Life cycle processes—Risk management
ISO/TS 16732:2005 Fire safety engineering—Guidance on fire risk assessment
Reference

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