Civil Defence Shelter Standards: Why Requirements Differ Between Countries

Civil defence shelters play a critical role in protecting people during armed conflicts, CBRN incidents, industrial accidents and other major emergencies.

However, the requirements for civil defence shelters can differ significantly from one country to another.

Although international guidance exists — including ISO 22359:2024, Security and resilience — Guidelines for hardened protective shelters — there is no single international technical specification establishing uniform minimum protection levels and detailed requirements for all civil defence shelters.

Instead, countries have developed their own regulations, shelter classifications, technical requirements, testing methods and approval procedures.

The fundamental objective is the same — protecting people — but the engineering requirements and methods used to achieve that protection can be considerably different.

Different Countries Prepare for Different Threats

Civil defence requirements are closely connected to national risk assessments.

Countries face different geographical, military, industrial and environmental threats. Shelter requirements therefore reflect the scenarios for which national authorities believe their population and critical infrastructure should be prepared.

One country may place significant emphasis on blast resistance, radiation fallout and CBRN protection, while another may concentrate on conventional blast effects, industrial accidents, natural disasters or shorter periods of emergency sheltering.

The required level and type of protection consequently vary between countries.

Different Civil Defence Philosophies

Countries have also developed different approaches to protecting their populations.

Some countries maintain extensive networks of purpose-built civil defence shelters incorporated into residential buildings, commercial properties and public infrastructure.

Others rely more heavily on designated public shelters, underground infrastructure, evacuation or the adaptation of existing spaces during an emergency.

These different civil defence concepts naturally result in different requirements for shelter structures, ventilation, life-support systems and protective equipment.

Historical Development of National Shelter Systems

Many national civil defence systems have developed over several decades.

Existing shelters were designed according to the regulations, technologies and threat assessments applicable at the time of construction. Authorities subsequently developed inspection procedures, maintenance requirements and new generations of technical regulations around this existing infrastructure.

As technologies and threats evolve, countries typically update their requirements while maintaining compatibility with their broader national civil defence systems.

This helps explain why shelter standards in different countries can follow significantly different technical approaches even when they are intended to provide protection against similar threats.

National Construction Regulations

A civil defence shelter is considerably more complex than simply a reinforced concrete structure.

A complete shelter may incorporate structural blast protection, blast doors and hatches, emergency exits, blast valves, gastight shut-off systems, ventilation and air distribution, CBRN filtration, overpressure control, emergency power, water and sanitation, fire protection, communications and monitoring systems.

Many of these systems are also governed by national building, electrical, fire-safety and construction regulations.

Because these regulations differ between countries, the requirements affecting civil defence shelters inevitably differ as well.

Different Protection Levels and Shelter Classes

Not every civil defence shelter is intended to provide the same level of protection.

Requirements can depend on the number of occupants, shelter location, building type, anticipated threats, required duration of occupancy and the role of the protected facility during an emergency.

A residential civil defence shelter, for example, can have significantly different requirements from a large public shelter, command facility or protected space designed to maintain critical operations during a crisis.

Countries may also use different shelter classifications and methods for defining these protection levels.

For this reason, simply describing a structure as a "civil defence shelter" does not define its actual level of protection.

Technical Requirements Can Differ Significantly

Even when two countries require the same type of protective component, the technical specifications may not be identical.

A blast door, for example, may be subject to different requirements concerning blast pressure, impulse, positive and negative pressure phases, allowable deformation, gas tightness, fire resistance, fragment protection and testing methodology.

Similar differences can apply to blast valves, overpressure valves, gastight dampers, emergency exits, CBRN filtration and ventilation systems and other critical shelter components.

Therefore, equipment designed or approved according to the requirements of one country cannot automatically be assumed to comply with the requirements of another.

This is particularly important for international shelter projects, where the applicable national and project-specific requirements should be established before equipment is selected.

Different Testing and Approval Procedures

Testing, documentation and certification are another important source of variation.

National requirements may specify different test procedures, acceptance criteria, documentation requirements or approval processes.

Depending on the system and applicable regulations, compliance may be demonstrated through physical testing, engineering calculations, technical documentation or a combination of these methods.

Consequently, two products designed to perform a similar protective function may be evaluated according to different procedures in different countries.

Understanding not only what performance is required, but also how that performance must be demonstrated, is therefore an important part of international civil defence shelter projects.

The Role of ISO 22359:2024

International standards and guidance nevertheless play an important role in shelter engineering.

A particularly relevant document is ISO 22359:2024 — Security and resilience — Guidelines for hardened protective shelters.

ISO 22359 provides international guidance concerning the design, use and maintenance of hardened protective shelters, including considerations related to shelter planning, structures, equipment and operation.

However, an important distinction needs to be made.

ISO 22359 is an International Standard that provides guidelines; it does not establish universal minimum protection requirements or exact technical specifications for hardened protective shelters.

The document therefore provides an internationally recognized framework and useful principles, but it does not replace national civil defence legislation, national shelter regulations or project-specific technical requirements.

National authorities may still establish specific requirements concerning structural resistance, blast pressure and impulse, CBRN protection, filtration capacity, gas tightness, overpressure, occupancy, emergency systems, testing methods and equipment approval.

Other ISO, EN and national standards may also apply to individual materials, components, structural calculations, fire performance, electrical installations, testing procedures and other aspects of shelter construction.

The design of a complete civil defence shelter may therefore involve a combination of international standards and guidance, national regulations, applicable building codes, technical standards and project-specific protection requirements.

Civil Defence Is Closely Connected to National Security

Civil defence is ultimately part of national preparedness and national security.

Governments determine which threats their populations and critical infrastructure should be prepared for and what level of protection is considered necessary.

These decisions depend on national risk assessments, defence and civil protection policies, existing infrastructure, construction practices and the country's overall emergency-preparedness strategy.

It is therefore understandable that detailed civil defence shelter requirements have historically remained primarily a national responsibility.

Understanding the Applicable Requirements Is Essential

For architects, engineers, contractors and equipment manufacturers working internationally, understanding these differences is essential.

Compliance cannot necessarily be determined by reference to a single standard.

The applicable national regulations, international standards and guidance, required protection level, testing criteria and project-specific specifications should all be considered when designing a shelter and selecting its protective systems.

A technically advanced product is not automatically suitable for every civil defence shelter.

Blast resistance, airflow, filtration capacity, gas tightness, overpressure, structural interfaces, installation methods, testing documentation and numerous other parameters must be evaluated against the actual requirements of the project.

This is especially important when selecting specialized protective technologies such as blast doors and hatches, blast and overpressure valves, gastight systems, CBRN filtration and ventilation systems, and other shelter life-support equipment.

Atmas Group — Expertise Across Different Shelter Standards and Requirements

Working with civil defence shelters internationally requires considerably more than knowledge of individual products.

It requires an understanding of how complete shelter systems function, how different protection requirements interact and, importantly, how national shelter regulations, classifications and technical norms differ between countries.

Atmas Group is a Finland-based company specializing in civil defence shelters, bunkers, protected facilities and infrastructure protection.

Our expertise covers both new shelter construction and the inspection, renovation and modernization of existing shelters and protected facilities.

We support projects with specialized engineering knowledge, technical consultation, equipment selection, product supply and system integration across the key protective and life-support systems required for civil defence shelters.

Deep Knowledge of Different Shelter Standards and National Norms

One of Atmas Group's important capabilities is our knowledge and practical understanding of different national shelter standards, regulations, protection concepts and technical requirements.

International shelter projects cannot be approached on the assumption that requirements applicable in one country will automatically be accepted in another.

Different national systems can specify different requirements for structural protection, blast loads, doors and hatches, blast valves, ventilation, CBRN filtration, gas tightness, overpressure, emergency exits, occupancy conditions, testing and documentation.

Our experience with different shelter concepts and international projects allows us to evaluate these requirements and configure solutions according to the applicable national regulations, recognized standards and project-specific specifications.

This knowledge is especially valuable when projects involve the modernization of existing shelters, adaptation of international technologies to local requirements or development of new protected facilities using equipment and systems from multiple manufacturers.

From Individual Components to Complete Shelter Systems

Atmas Group's capabilities extend beyond the supply of individual shelter components.

Depending on the project, our scope can include:

• civil defence shelter and protected-facility consultation;

• design and engineering support;

• shelter inspection, renovation and modernization;

• CBRN filtration and ventilation systems;

• CO and CO₂ control solutions where required;

• blast doors, hatches and protective gates;

• blast, overpressure and gastight valves;

• gastight air-management and shut-off systems;

• emergency exits and protective penetrations;

• structural, blast, ballistic and forced-entry protection solutions;

• EMP and infrastructure protection solutions;

• specialized shelter equipment and accessories;

• equipment integration and installation support;

• testing and commissioning support;

• development and manufacture of specialized protective products and systems.

This system-level approach is important because the performance of a shelter cannot be determined by one component alone.

The structure, doors, openings, blast valves, ventilation, filtration, pressure control and life-support systems must function together as an integrated protective system.

A highly rated blast door, for example, cannot compensate for inadequately protected ventilation openings. Similarly, an advanced CBRN filtration system cannot provide the intended protection if the shelter cannot maintain the required gas tightness and controlled overpressure.

Understanding these interactions is fundamental to effective shelter engineering.

Applying the Right Requirements to the Right Project

There is no universal shelter configuration suitable for every country, threat or application.

Atmas Group therefore approaches projects by first understanding the applicable standards and regulations, required protection level, anticipated threats, shelter capacity, operational requirements and specific project conditions.

From there, appropriate protective technologies and systems can be selected and integrated into the overall shelter concept.

International guidance such as ISO 22359:2024 can provide valuable principles. National regulations and shelter norms establish additional requirements, while individual projects can introduce further technical specifications depending on their purpose and required level of protection.

Our objective is to combine this understanding with specialized engineering knowledge and proven protective technologies to provide practical and technically appropriate solutions for civil defence shelters and protected facilities in different markets worldwide.

Different Requirements — The Same Objective

Civil defence shelter requirements differ between countries for practical, historical, technical and security-related reasons.

International standards and guidance provide valuable common principles, while national regulations and shelter norms reflect each country's civil defence system, construction practices, risk environment and preparedness strategy.

For international projects, the challenge is therefore not simply to provide protective equipment.

It is necessary to understand which requirements apply, what level of protection is required, how the different shelter systems must work together and how the required performance must be demonstrated.

This is where experience across different shelter concepts, standards, national requirements and protective technologies becomes particularly important.

Atmas Group combines this knowledge with specialized engineering, protective technologies and international project support to provide solutions for civil defence shelters, bunkers and protected facilities worldwide.

Different countries. Different requirements. Different technical approaches. One fundamental objective — protecting people.