International Review of Surveillance and Control of Workplace Exposures: NOHSAC Technical Report 5

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3.6 Types of surveillance systems

As much as there is ambiguity in defining exposure and the types of surveillance, so too is there ambiguity in the way difference surveillance systems are broadly classified.

Surveillance information is collected by a variety of means, as suggested in Figure 6. These various sources of information and the use of the system lead to a variety of options for classification. For example, Rantanen et al^[2] categorise the data sources as administrative registers and statistics, questionnaire-based surveys, expert assessments systems, and observational surveys, while Smulders^[38] suggests that OHS monitoring systems be described as workforce systems, worker surveys or questionnaires, exposure databases, registers of substances and worker health surveillance systems, including registers of accidents and diseases, sickness leave or absenteeism systems, and multi-source and policy-directed systems. Levels of analysis for classifying systems differ, depending on the source of the classification, and in some cases, different levels of analysis are mixed in the one classification system. For the purposes of this review and based on the published literature, the following classifications or groupings of work environment surveillance systems have been adopted in an attempt to reconcile some of the ambiguity:

Integrated systems
Working conditions surveys
Workplace observations and OHS services data
Registers.

These are described as follows and summarised in Table 1.

Group 1: Integrated systems

This category looks at multi-source information that is combined into one system. The information contained within the system looks at both exposure information and health outcome information (injury, illness disease, absenteeism information) in a combined or integrated system. While information from both exposure and outcome data is included, exposure data is the focus, as well as the usefulness and effectiveness of combining both sources of data into one system.

This system takes into account exposure surveillance by methods associated with comprehensive surveillance, routine surveillance, workforce systems, exposure databases, relevant population systems and industry surveillance systems. LaMontagne et al^[39] have argued that integrated exposure database and surveillance systems hold considerable promise for improving workplace health and safety and have proposed a foundation from which to build practical and effective exposure surveillance systems. They argue that implementation of exposure databases and surveillance systems can likely be improved by the development of systems that are more responsive to workplace or organisational-level needs. Some examples of such systems are the Danish National System (national system) and Duke University’s DHSSS (state and industry-specific system).

Group 2: Systems for working conditions data; surveys

This group looks at surveillance systems or databases that focus on work conditions and major surveys. This system looks at exposure surveillance by methods associated particularly with workforce systems (labour force surveys). These methods may be national or industry-specific. An example of this group of systems is the National Occupational Exposures Survey conducted in the USA.

Group 3: Systems for workplace observations; OHS services data

This category focuses on surveillance systems or databases that collate workplace observations or data from OHS services such as industrial/occupational hygienists, ergonomists and so forth, as well as inspectorate data. Also included in this category are systems which collate information contained within job or task exposure matrices.

This system looks at exposure surveillance by methods associated with routine and comprehensive surveillance, exposure databases, industry surveillance systems and relevant population systems. An example of a system in this category is the FINJEM database containing job exposure matrices for tasks nationally in Finland.

Group 4: Systems containing registers

This system looks at exposure surveillance by methods associated with registers of sources, for example, chemical hazards, physical hazards and so on, or exposures. For example, Finland’s ASA register records exposures to a variety of carcinogens. This category also includes other legislative or passive information recording systems, for example, HIV surveillance systems around the world, or the dermatitis reporting system, which includes information about exposures characteristics.

Within the groupings are various frameworks for data collection qualified by adjectives such as “routine”, “population” and “industry”, by which periodicity and target data sources are defined. These qualifying terms are used in the literature without being defined and thus are interpreted by their English language meaning. Among the key frameworks used, exposure databases and observations, worker or workforce surveys and questionnaires, and registers feature significantly.

Table 1 Types of work environment surveillance systems
Group 1 Integrated Systems	Group 2 Working Conditions Surveys	Group 3 Workplace Observations OHS Services Data	Group 4 Registers
Content
Single systems combining or amalgamating exposure and health outcome information	Systems which collate survey information on working conditions	Systems collating OHS observations and/or measurements taken in workplaces	Incorporates databases which collate exposure information in listings or registers
Framework
Comprehensive surveillance Routine surveillance Workforce systems (labour force survey and workplace observation) Exposure databases Industry surveillance Relevant population surveillance	Workforce systems (labour force survey)	Routine surveillance Exposure databases Industry surveillance Relevant population surveillance Workplace observations Other (exposure databases developed from published literature)	Registers of substances (and other forms of registers)
Methods
Broad indicators: Injury, illness, disease, absenteeism information	Broad indicators: Safety level, hazard exposures, risk factor exposure, work organisation, job satisfaction and work security	Broad indicators: Levels of contaminant	Broad indicators: Sources of exposure, exposure incidents, products/equipment, consumption statistics
Instruments: Survey, observations population data	Instruments: Questionnaires (interview style or self report)	Instruments: Sampling equipment, ergonomic measurements, etc. Workplace observation	Instruments: Notification forms/methods within the country
Data sources: Industry Population	Data sources: Sample populations from nation, industry, workplace and other sample breakdowns	Data sources: Industrial/occupational hygienists, ergonomists, inspectors collecting information from personal or area sampling and/or assessment	Data sources: Businesses (usually employers or their representatives)
Issues: On-going data gathering, potentially some under- reporting	Issues: Regular data gathering, minimal under-reporting	Issues: On-going data collection, minimal under-reporting Informs job/task exposure matrices	Issues: Linked to legislative or other passive reporting requirements, some under-reporting
Example
Danish Surveillance System of Progress in Action Programme for a Clean Working Environment	Nordic Occupational Skin Questionnaire	Singapore National Database for Noise and Chemical Exposure	Finnish ASA register (Exposure to Carcinogens)