Occupational 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 recognising, evaluating and controlling the risks". The International Occupational Hygiene Association (IOHA) refers to Occupational Hygiene as the discipline of anticipating, recognising, 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.
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 eg since 1900, asbestos exposures that have affected the lives of tens of thoundands 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 characteristing 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.
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.
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, prioritising hazards, determining the requirements for measurement and establishing some immediate control of potential exposures.
An Occupational Hygienist may use one or a number of commercially available electronic measuring devices to measure noise, vibration, ionising and non-ionising 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.
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.
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 there 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.
The Occupational Hygienist may be involved with the assessment and control of physical, chemical, biological or environmental hazards in the workplace or community that could cause injury or disease. Physical hazards may include noise, temperature extremes, illumination extremes, ionizing or non-ionizing radiation, and ergonomics. Chemical hazards related to Dangerous Goods or Hazardous Substances are frequently investigated by Occupational Hygienists. Other related areas including Indoor air quality (IAQ) and safety may also receive the attention of the Occupational Hygienist. Biological hazards may stem from the potential for legionella exposure at work or the investigation of biological injury or effects at work, such as dermatitis may be investigated.
As part of the investigation process, the Occupational Hygienist may be called upon to communicate effectively regarding the nature of the hazard, the potential for risk, and the appropriate methods of control. Appropriate controls are selected from the hierarchy of control: by Elimination, Substitution, Engineering, Administration and Personal Protective Equipment (PPE) in order to control the hazard or eliminate the risk. Such controls may involve recommendations as simple as appropriate PPE such as a 'basic' particulate dust mask to occasionally designing dust extraction ventilation systems, work places or management systems in order to manage people and programs for the preservation of health and well-being of those who enter a workplace.
The basis of the technical knowledge of Occupational Hygiene is from competent training in the following areas of science and management.
However, it is not rote knowledge that identifies a competent Occupational Hygienist. There is an "art" to applying the technical principles in a manner that provides a reasonable solution for workplace and environmental issues. In effect an experienced "mentor", who has experience in Occupational Hygiene is required to show a new Occupational Hygienist how to apply the learned scientific and management knowledge in the workplace and to the environment issue to satisfactorily resolve the problem.
To be a professional Occupational Hygienist, experience in as wide a practice as possible is required to demonstrate knowledge in areas of Occupational Hygiene. This is difficult for "specialists" or those who practice in narrow subject areas. Limiting experience to individual subject like asbestos remediation, confined spaces, indoor air quality, or lead abatement, or learning only through a textbook or “review course” can be a disadvantage when required to demonstrate competence in other areas of Occupational Hygiene.
Information presented in Wikipedia can only be considered to be an outline of the requirements for Occupational Hygiene training. This is because the actual requirements in any Country, State or Region may vary due to educational resources available, industry demand or Regulatory mandated requirements.
Academic programs offering industrial hygiene Bachelors or Masters degrees in United States may apply to the Accreditation Board for Engineering and Technology (ABET) to have their program accredited. As of October 1, 2006, 27 institutions have accredited their industrial hygiene programs. Accreditation is not available for Doctoral programs.
The International Occupational Hygiene Association was formed in 1987. Its membership are the national professional associations, now numbering more that 20 organizations and representing over 20,000 occupational hygienists worldwide.
National professional societies include the following (in alphabetical order):
Journal of Occupational and Environmental Hygiene  - published jointly since 2004 by the American Industrial Hygiene Association and the American Conference of Governmental Industrial Hygienists, replacing the American Industrial Hygiene Association Journal and Applied Occupational & Environmental Hygiene
Annals of Occupational Hygiene  - published since 1958 by the British Occupational Hygiene Society
In 2005, the Australian Institute of Occupational Hygiene (AIOH) has accredited professional occupational hygienist through a certification scheme. Occupational Hygienists in Australian certified through this scheme are entitled to use the phrase Certified Occupational Hygienist (COH) as part of their qualifications.
Practitioners who successfully meet minimum education and work-experience requirements and pass a written examination administered by the American Board of Industrial Hygiene (ABIH) are authorized to use the term Certified Industrial Hygienist (CIH) or Certified Associate Industrial Hygienist (CAIH). Both of these terms have been codified into law in many states in the United States in order to identify minimum qualifications of individuals having oversight over certain activities that may affect public health.
ABIH Certification examinations are offered during a spring and fall testing window each year in the US, and are also offered at locations outside the US, including Canada, Australia, and East Asia among other locations.
The CIH designation is the most well known and recognized industrial hygiene designation throughout the world.
In Canada, a practitioner who successfully completes a written and an interview administered by the Canadian Registration Board of Occupational Hygienists can be recognized as a Registered Occupational Hygienist (ROH) or Registered Occupational Hygiene Technician (ROHT).
The Faculty of Occupational Hygiene, part of the British Occupational Hygiene Society, represents the interests of professional occupational hygienists.
Membership of the Faculty of Occupational Hygiene is confined to BOHS members who hold a recognised professional qualification in occupational hygiene.
There are three grades of Faculty membership:
All Faculty members participate in a Continuous Professional Development (CPD) scheme designed to maintain a high level of current awareness and knowledge in occupational hygiene.
It is difficult to create a comprehensive list of references for Occupational Hygiene. Firstly, a list is required for the practices and methodologies involved with the profession of Occupational Hygiene. This list alone can be quite extensive. Secondly, a list of references for each subject area, issue or problem to be resolved from an Occupational Hygiene stand point is required and this information is to be applied to each workplace within each regulatory framework. More importantly the list of references will change due to both changes in technology and changes in requirements for Regulatory compliance. The reference list below may help to get started in self-educating, researching a problem or resolving an issue.
Items below available from ACGIH at:  (Click on ‘Products’ then ‘Publications’ and select items from the appropriate list) Definitions, Conversions, and Calculations for Occupational Safety and Health Professionals, 3rd Edition, Edward W. Finucane, ISBN 978-1-56670-640-7, 2006, US$97.95 Fundamentals of Industrial Hygiene, 5th Edition, National Safety Council, ISBN 978-0-87912-216-4, 2001, US$191.53 Modern Industrial Hygiene, 2 Volume Set, Jimmy L. Perkins, ISBN 978-1-882417-75-9 and 978-1-882417-48-3, 2008 and 2003, US$179.95 Patty’s Industrial Hygiene, 5th Edition: 4 volume set, Robert Harris (Ed.), ISBN 978-0-471-29784-0, US$1,800.00
Principles of Occupational Hygiene & Health, Tillman C. (Ed), Australian Institute of Occupational Hygienists, Allen & Unwin, 2007, ISBN 9781741750584, A$80. Purchase from AIOH at: 
Also from ACGIH:  Casarett and Doull’s Toxicology: The Basic Science of Poisons, 7th Edition, Curtis D. Klaassen (Ed), ISBN 978-0-07-147051-3, 2007, US$115.00
Dorland’s Illustrated Medical Dictionary, 31st Edition, Dorland/ W.B. Saunders, ISBN 978-1-4160-2364-7, 2007, US$49.95
Patty's Toxicology, 5th Edition, 9 Volume Set, Eula Bingham, Barbara Cohrssen, and Charles H. Powell (eds.), ISBN 978-0-471-31943-6, Wiley-Inter-science (publisher), 2001, US$2,915.00
Sax's Dangerous Properties of Industrial Materials, 11th Ed., Three Volume Print Set, Richard J. Lewis, Sr. ISBN 978-0-471-47662-7, 2004, US$650.00
Toxicology on-line tutorials: 
Health, Safety and Occupational Hygiene Issue Search: World health Organisation (WHO): 
International Labour Organisation, ILO Encyclopaedia of Occupational Health and Safety, 4 Volume set, 4th Edition, 1998, ISBN 9221092038. Purchase from ILO publications 150 Sw. Frs.; € 100; US$ 120. On line at:  Book description at: 
UK HSE:  (Purchase Only). Check other areas of HSE site for further publicly available information.
Indoor Air Quality on-line educator: 
Descriptive OH&S information: Canada:  then press ‘OHS Answers’ or ‘MSDS’ link. MSDS and Chemical Information:
(US) Agency for Toxic Substances and Disease Registry: 
(US) National Library of Medicine: 
(US) National Toxicology Program: 
International Agency for Research on Cancer: 
RTECS:  (by Subscription only)
Also try the manufacturer or suppliers web site. Many larger businesses maintain their own product and chemical information.
There are also many subscription services available (CHEMINFO, OSH, CHEMpendium, Chem Alert, Chemwatch, Infosafe, Micromedex TOMES® Plus, OSH Update, OSH-ROM®, et cetera).
Other educational material: 
There is a varying degree of information available from published articles available on-line. In some instances the full article can only be obtained by subscription to the publishing organisation.
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 is at 
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 labelling) ISO 14024:1999 Environmental labels and declarations — Type I environmental labelling — 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