Protected spaces

Protected spaces may offer the best protection against blast, flying glass and other fragments. They may also offer the best protection when the location of the possible bomb is unknown, when it may be near your external evacuation route or if there is an external CBR attack.

Since glass and other fragments may kill or maim at a considerable distance from the centre of a large explosion, moving staff into protected spaces is often safer than evacuating them onto the streets. Protected spaces should be located:

• in areas surrounded by blast-resistant partitions or full-height masonry or concrete walls e.g. internal corridors, toilet areas or conference rooms
• away from windows, external doors and walls
• away from the area in between the building's perimeter and the first line of supporting columns (known as the 'perimeter structural bay')
• away from stairwells or areas with access to lift shafts where these open at ground level onto the street, because the blast can travel up them. If, however, the stair and lift cores are entirely enclosed, they could make good protected spaces
• avoiding ground or first floor if possible
• in an area with enough space to contain the occupants.

When choosing a protected space, seek advice from a structural engineer with knowledge of explosive effects and do not neglect the provision of toilet facilities, seating, drinking water and communications.

Consider duplicating critical systems or assets in other buildings at sufficient distance to be unaffected in an emergency that denies you access to your own. If this is impossible, try to locate vital systems in parts of your building that offer similar protection to that provided by a protected space.

Communications

Ensure that designated staff know their security roles and that they or their deputies are always contactable. All staff, including night or temporary staff, should be familiar with any telephone recording, redial or display facilities and know how to contact police and security staff in or out of office hours.

It is essential to have adequate communications within and between protected spaces. You will at some stage wish to give the all clear, or tell staff to remain where they are, move to another protected space or evacuate the building. Communications may be by public address system (in which case you will need standby power), hand-held radio or other standalone systems. Do not rely on mobile phones. You will also need to communicate with the emergency services. Whatever systems you choose should be regularly tested and available within the protected space.

Converting to open plan

If you are converting your building to open-plan accommodation, remember that the removal of internal walls reduces protection against blast and fragments. Interior rooms with reinforced concrete or masonry walls often make suitable protected spaces, as they tend to remain intact in the event of an explosion outside the building. If corridors no longer exist then you may also lose your evacuation routes, assembly or protected spaces, while the new layout will probably affect your bomb threat contingency procedures.

When making such changes, try to ensure that there is no significant reduction in staff protection, for instance by improving glazing protection. If your premises are already open plan and there are no suitable protected spaces, then evacuation may be your only option.