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The National Population Database – a tool for UK contingency planning

Background to the National Population Database (NPD) development

Britain's Health and Safety Executive (HSE) is the body responsible for regulation of risks to health and safety arising from work activity in Britain. HSE ensures compliance with health and safety legislation covering factories, farms, major hazard process sites, offshore gas and oil installations and the safety of the gas grid, plus many other activities which affect the protection of both workers and the public.

The Health and Safety Laboratory (HSL), which is part of the HSE, provides scientific support and research for these duties. One area of expertise relates to the development of Geoanalytical methodologies, techniques and applications which provide tools and evidence to inform regulatory activities. As part of this work programme HSL have developed the National Population Database (NPD), which is a GIS based tool which estimates population density and distribution for a wide range of population types from local to national level for the UK. The NPD includes residential, workplace, retail, leisure, tourism and transport population estimates and also populations that may be more susceptible to harm such as populations in schools, hospitals, care homes and nurseries. The NPD is available at a range of resolutions down to building level detail, and incorporates information from multiple sources. The methodology behind the NPD involves identifying and locating a range of features, including building types, infrastructure and land use areas, to which population multipliers are then applied to produce estimates of the different populations. Different multipliers are applied to different population types and where possible, additional multipliers are created to account for variation in population at different times of day. Fundamental to HSL's approach in developing the NPD is the identification of appropriate source data and the cleansing, linking and joining of these disparate datasets to generate population intelligence. Over the past 10 years HSL has been developing and improving numerous data matching algorithms and methodologies to create the range of population layers within the NPD, leading to the NPD becoming a key tool for HSE and for other UK Government Departments.

The NPD was initially developed for HSE to aid major accident hazard modelling, where estimating numbers and types of populations at risk from potential accidents at major hazard sites was, and still is, essential. Since its initial creation, use of the NPD has widened considerably and it is now a key tool informing risk management as well as emergency and contingency planning across the UK Government. This article outlines some of the ways the NPD is being used to help assess and manage risk from potential industrial and nuclear hazards, and more recently from natural hazards as well.

Using the NPD for Contingency Planning

The NPD is regularly used to identify and estimate the numbers and types of populations at risk from a range of hazards. By using the range of layers available within the NPD a comprehensive picture of population type, count and location can be built up. For example, the NPD sensitive layer can provide locations and numbers of people that may be more sensitive to harm, such as children, the elderly or hospital patients. Populations that may be hard to evacuate may also be of interest, such as those in prisons, in town centres or retail areas, or in large stadia. These are available from the communal and leisure layers within the NPD. Additionally, much scenario planning work involves examining worst-case scenarios, which requires estimates of the maximum populations in an area. This is often the night time residential population, one of many residential scenarios, in combination with other layers such as hospitals, care homes and prisons.

Hazards that HSE regulate include industrial hazards, such as those associated with large chemical works and pipelines. HSE is required to regulate the risk to the population from major hazard sites through its duties under the EU SEVESO Directive and the NPD is used to inform this process. Estimates of the population at risk from accidents at these sites are used to inform risk assessment and risk estimation work and manage the risk associated with the sites. The NPD can be used to provide detailed estimates of the numbers and types of populations within close proximity of a pipeline carrying a hazardous substance. This information is used by both the HSE and also the pipeline operators to ensure the relevant legislation is complied with and sufficient risk mitigation measures are in place. This type of population information can also be used to prioritise interventions based on risk and for informing Land Use Planning advice.

The NPD can also be used to identify property and infrastructure that is at risk from hazards, as it contains comprehensive building classification and usage information and also extensive workplace details including information relating to workplace activity based on their Standard Industry Classification (SIC). This enables the NPD to be used to:

1)      identify the numbers and types of property and infrastructure at risk from a hazard;

2)      identify workplaces that may be a higher priority for risk mitigation measures;

3)      estimate the economic impacts of events as a result of loss of activity and clean-up costs;

4)      provide an indication of workplace activity that might be potentially hazardous to the surrounding area, for example the use of welding equipment in scrap yards.

Following on from recent incidents, including the fire at the oil refinery at Buncefield (UK) in 2005, the team at HSL are using the NPD to inform studies for HSE looking at the economic impact of industrial accidents.

In a similar way the NPD is also used to determine potential numbers and types of populations, properties and infrastructure exposed to environmental hazards, such as flooding. Footprints of a natural hazard can easily be superimposed over NPD information to provide details of what and who is affected by an event.

The development of the NPD as an asset dataset provides a valuable basis for further analysis and the team at HSL have gone on to develop an additional range of bespoke applications and a number of analytical services based on the NPD that provide evidence and tools for contingency planning.

Development of Emergency Planning and Response Tools

Using the NPD as a basis, the team at HSL have developed an emergency response tool for the Office for Nuclear Regulation (ONR). ONR regulates 37 licensed nuclear sites in the UK and the tool developed by HSL allows ONR staff to access the NPD data in a clear and intuitive way, which is especially important during an emergency. Wind direction and speed information can be displayed over the population within a 50km radius of a nuclear site and overviews of the range of potential populations exposed in the event of a nuclear emergency can be provided. In addition to the summaries of the types of exposed populations, details of the population and property affected are also available. This range of scales allows the tool to be used to inform the management of the situation at a range of levels, including identification of populations with specific evacuation requirements and the extent of counter measures required.

HSL are also part the Natural Hazard Partnership (NHP), a cross-UK Government group formed of key departments and agencies brought together to improve the provision of advice to decision makers and emergency responders for natural hazards. As well as wider advice around natural hazards, the NHP is developing a new approach to the forecasting of natural hazard events such as flooding, landslides and high winds via the creation of the Hazard Impact Model (HIM).  The HIM aims to provide a new insight into the consequences of natural hazard events through a consideration of the impacts, modelling the potential for danger, damage and disruption alongside modelling of the hazard itself. HSL are leading on the vulnerability and impact modelling aspects of the HIM and are currently developing a proof of concept HIM for Surface Water Flooding hazards, working with NHP partners from the UK Centre for Ecology and Hydrology (CEH).  The HIM identifies what might be at risk from Surface Water Flooding, and uses vulnerability and impact indicators to provide information to the end-users.  Figure 3 illustrates an example of the output from the proof of concept Surface Water Flooding HIM for a case study from summer 2011. Outputs from this case study have been compared to media reports from the event to provide an initial verification of the HIM concept. This work is currently ongoing, with the aim of developing a proof of concept system for use by UK stakeholders.

Future Development of the NPD

HSL have established an update and maintenance schedule for the NPD. This includes quarterly updates to the existing layers plus a programme of research and development focusing on the creation of new layers.  New NPD layers are developed largely in response to usage requirements from customers and are determined by the availability of new data sets and by the development of appropriate methodologies to represent these populations. Future NPD layers being developed include additional transport layers such as a rail population and a pedestrian layer, along with additional leisure accommodation and retail layers.

Dr Helen Balmforth

Health and Safety Executive, Harpur Hill, Buxton, Derbyshire, SK17 9JN, UK.

© 2014 British Crown Copyright, Health and Safety Executive

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