Radiation Hazards in Shelters: How to Protect Yourself from Radon While Staying in a Shelter?

In the context of the full-scale war in Ukraine, civil defense structures (shelters, basements and bunkers) have become an integral part of everyday life for millions of Ukrainians. On the one hand, these are the safest places during shelling. On the other hand, they are areas that may not have been designed for people to stay in for extended periods. Basements may contain household items, including those with radioactive substances, and may also have high radon concentrations in the air (since ventilation of basement spaces in non-specialized shelters is rarely maintained).

Long-term presence of the public in closed underground spaces poses radiation risks. Radon, a naturally occurring radioactive gas, can accumulate in poorly ventilated areas. In this context, studying radon concentrations in shelters, assessing factors of its accumulation and developing measures to reduce its impact are of particular relevance for the public health and civil protection system of Ukraine.

What Is Radon and What Threats Does It Pose to Human Health?

Radon is an inert, odorless, colorless and tasteless radioactive gas generated during the natural radioactive decay of uranium present in rocks and soils.

Radon is dangerous because of its radiotoxicity and carcinogenicity. The human bronchopulmonary system is a target for daughter decay products (DDPs) – short-lived isotopes of polonium, bismuth and lead. In the environment, DDPs, which are metals, are attracted to the smallest dust particles and water droplets, forming a mixture that is inhaled by a person into the lower, most vulnerable parts of the respiratory tract.

The decay of radon nuclei and its DDPs in lung tissue causes microburns, since virtually all the energy of alpha particles is absorbed at the point of decay. According to WHO, up to 14% of all lung cancer cases worldwide are associated with human exposure to this radioactive gas.

The adverse effects of radon also pose a significant threat to a child’s body. Children belong to the high-risk group because of the smaller size of the body and organs, in particular the lungs, metabolic characteristics of the growing organism, and greater radiosensitivity of organs and body systems. For example, a primary school student spending 8 hours a day for 180 days a year in a classroom where radon levels are twice the permissible limit will receive a radiation dose 10 times higher than if they lived at the boundary of the nuclear power plant control area.

Radon Hazard in Indoor Spaces

Ukraine is one of the countries with high radon potential, which is due to the geological structure of certain regions and the prevalence of uranium-bearing rocks. The greatest potential hazard exists within the Ukrainian Crystalline Shield – a territory extending along the middle course of the Dnipro River in a strip more than 1,000 km long and about 250 km wide. Shelters operating in such territories may become zones of elevated radon concentration, posing additional risks to public health, particularly to the respiratory system.

Radon poses a particular threat to the Kirovograd Region, which contains significant deposits of uranium ores. Previously, the region implemented nuclear and radiation safety programs aimed at combating radon. For example, the Stop-Radon Regional Program examined radon-222 concentrations in the air of 187 preschool and general educational institutions.

Analysis of the measurement results showed that radiation and health standards established for such institutions were exceeded in more than 70% of the surveyed buildings. Of 30 rooms in the Malovyskivskyy District, the limit was exceeded in 23 cases; the exceedance was fivefold in 8 cases and tenfold in 3 cases. In some educational institutions of the Kompaniyivskyy and Haivoronskyy Districts, radon activity in the air exceeded the limit by 20 to 46 times.

Under the Comprehensive Program for Protecting the Region’s Population against Ionizing Radiation Effects for 2014–2018, a series of radiometric studies were conducted on rooms and water from artesian wells for radon content and on environmental sites to determine the activity of natural radionuclides, the extent of medical research impact, etc. However, the Program has since expired and no new programs have been introduced to replace it.

Radon enters buildings through microcracks in the floor or at floor-wall joints, gaps around pipes or cables, small pores in hollow block walls, hollow walls, and sewage drains. Radon levels are usually higher in basements, cellars and living spaces in direct contact with the soil. However, significant radon concentrations may also be detected above the ground floor, since building materials made from uranium-containing rocks can serve as a radon source. This is why radon levels vary significantly even between neighboring buildings and can also fluctuate within a single building from day to day and even hour to hour.

In Ukraine, radon concentration is regulated by the Radiation Safety Standards of Ukraine (NRBU-97), which establish an average annual equivalent equilibrium activity concentration (EEAC). The standard limit for ordinary rooms with continuous occupancy is 100 Bq/m³ (for buildings commissioned before 1997) and 50 Bq/m³ for new and reconstructed buildings.

* EEAC is the average annual activity concentration of radon in equilibrium with its daughter decay products that would yield the same potential alpha energy per unit volume as the actual mixture.

The radon content standard for water is established by the State Health and Safety Rules and Regulations “Health and Safety Requirements for Drinking Water Intended for Human Consumption” (DSanPiN 2.2.4-171-10) and amounts to 100 Bq/dm³.

For children’s healthcare, health resort and health treatment institutions, as well as building rooms and structures being constructed or reconstructed for continuous public occupancy, the EEAC standard is 50 Bq/m³.

* Radon concentration in air is measured in becquerels per cubic meter and in water in becquerels per liter.

However, the main current difficulty is that the activity concentration (AC) is used in Europe as the basic regulatory indicator in anti-radon standards and includes only radon without its daughter decay products. For an adequate comparison of Ukrainian standards with European ones, it is necessary to apply the equilibrium factor between radon and its decay products to convert AC to EEAC. In the harmonization with European requirements, this discrepancy should be eliminated, which will result in convergence of numerical standards, coordination of measurement procedures, dose assessment methods and reporting principles in line with European standards.

How Radon Is Combated Around the World

Countering the adverse effects of radon is possible through effective national policy and regulatory measures.

The United States has one of the most developed radon protection systems in the world, coordinated by the Environmental Protection Agency (EPA). The main legal foundation for radon control in the United States is the Indoor Radon Abatement Act (IRAA) of 1988, which became part of the Toxic Substances Control Act.

The key mechanism for federal support is the State and Tribal Indoor Radon Grants (SIRG) Program, which has been operating for more than 30 years. SIRG grants are not available directly to private individuals or homeowners; they fund state agencies implementing local initiatives aimed at conducting radon surveys and collecting radon data; developing and distributing educational materials for the public; purchasing and maintaining measuring and analytical equipment; training specialists and administering certification programs; demonstrating radon mitigation methods and technologies.

In addition, the United States has special social assistance programs:

• Colorado offers the Low-Income Radon Mitigation Assistance (LIRMA) for direct financial assistance to low-income homeowners to cover the costs of system installation and subsequent testing.
• Many states hold events during National Radon Action Month (January). For example, the North Carolina Department of Health provided 8,000 free radon test kits to residents in 2026. Stearns County, Minnesota, also distributes 200 kits annually.
• Pennsylvania has a Newborn Program. The Department of Environmental Protection cooperates with hospitals to provide parents of newborns with a coupon for a free radon test.

In Europe, there is a large professional community uniting those working in radon-related fields – the European Radon Association (ERA). The community includes scientists, technologists, public health specialists and others. The interests of ERA members cover epidemiology, radiation dosimetry, instrumentation development and measurement protocols, radon mitigation technologies in construction, as well as control and regulatory strategies.

The Czech Republic has one of the longest-running radiation monitoring programs in Europe, which began systematic inspections in the early 1990s. The Czech model is distinctive in that it includes a “radon index” for construction sites, which determines the potential radon risk at a given location based on geological conditions and measurements of radon volumetric activity in the soil. In addition, the Czech government has historically provided substantial subsidies for the renovation of existing buildings and schools, supporting a network of over 100 authorized commercial companies providing radon diagnostics and mitigation services.

Norway, Sweden and Finland are among the countries with the highest average indoor radon concentrations in the world. Geological conditions and a cool climate create serious challenges, but the radon problem can be addressed in a cost-effective manner. Although all Nordic countries have radon permissible limits of 100–300 Bq/m³, Norway has the most stringent and detailed requirements for mandatory installation of radon protection systems at the foundation stage.

The main methods used by these countries to combat radon, particularly in underground facilities and shelters:

• Active and passive soil depression

This is considered the most effective method in Nordic countries. Rather than dealing with the gas once it is already inside the room, it is extracted directly from beneath the foundation: a special radon sump is installed under the concrete floor slab, connected to a pipe that leads to the building’s roof. In a passive system, the gas exits naturally due to the pressure difference. In an active system, a fan is connected to the pipe, continuously creating a low-pressure zone beneath the shelter. Radon is vented to the atmosphere before it ever enters the room.

• Radon membranes

Since 2010, installation of a radon membrane (Standard TEK10/TEK17) has been mandatory in Norway for all new buildings. This is a heavy-duty elastic sheet laid under the foundation or floor. Particular attention is paid to sealing joints and points where pipes or cables pass through the floor – these are the weakest spots through which radon seeps into the room.

• Balanced ventilation

Sweden and Finland rely on automated ventilation systems with heat recovery. The system simultaneously exhausts radon-laden air and supplies fresh air. It is important that the air pressure inside the room be slightly higher than or equal to external pressure. If a “vacuum” is created inside a shelter (for example, when only exhaust ventilation operates without air intake), the system will literally draw radon from the ground through microcracks.

European Union countries are guided by Directive 2013/59/Euratom, which establishes uniform basic safety standards for protecting the health of the public, workers and patients from the hazards of ionizing radiation. The Directive requires the establishment of national reference levels for radon, the development of national radon action plans, and the conduct of monitoring and public information activities.

For Ukraine, this Directive is a key reference point for harmonizing national legislation with EU law, in particular in the field of radon monitoring. In the framework of Directive implementation, the Action Plan for Reducing Exposure of the Public to Radon and Its Decay Products and Minimizing Long-Term Risks from Radon in Residential and Non-residential Buildings and at Workplaces for 2020–2024 was approved by Cabinet Resolution No. 1417-r dated 27 November 2019. Ultimately, this plan was only partially implemented. Although it envisaged monitoring of radon levels in building air throughout Ukraine, data are in fact available for only some regions. As a result, a comprehensive database of radon concentrations in Ukraine was never established.

The next step in this field was the adoption of the Procedure for Radon Monitoring in Ukraine and Notification on Radiation Risks, along with the Methodology for Radon Monitoring, both enforced in 2023.

The Procedure defines the organizational and procedural principles of state radon monitoring in Ukraine. It establishes where and at which facilities monitoring is to be carried out (residential buildings, public and work premises), the entities responsible for measurements and summary of the results, the mechanism for informing the public and authorities on exceedance of permissible radon concentrations and associated radiation risks, and general requirements for managing public health risks.

The Methodology for Radon Monitoring defines, in particular, the methods and conditions for measuring indoor radon volumetric activity, requirements for measurement instruments, detectors and measurement duration, and rules for selecting rooms and measurement points.

In order to achieve tangible results and increase public awareness of radon, scientists recommend introducing training programs for radon protection specialists who will implement action plans at the local level. Through the implementation of anti-radon measures, these specialists will be able to reduce social tension in communities associated with radon hazards on Ukrainian territory.

How to Minimize Risks and Make a Shelter Safe

Even under difficult circumstances, there are simple steps that can minimize risks:

1. Ventilation adjustment and improvement

Locate all ventilation openings in the basement or foundation. They are often bricked up, filled with foam, or covered with rags to retain warmth. If such openings are fitted with small metal mesh, these should be cleaned of dust and cobwebs. This can increase air flow by 30–40%.

It is also advisable to install a standard household exhaust fan in the ventilation duct. It is preferable to supply fresh air inward, creating overpressure, rather than simply exhausting air outward. Overpressure prevents radon from penetrating through the floor. Installing a floor fan directed to push air from an entrance or open window into the room will also help.

• Regular ventilation of shelters

Whenever there is a safe opportunity (during breaks between air raid alerts), basements should be ventilated intensively.

• Wet cleaning

Radon decay products travel on dust particles, so dry sweeping should be avoided. All surfaces (walls, floors and benches) should be cleaned with a damp method. If there are old mattresses or blankets in the shelter that have been stored in the basement for years, they should be taken outside and beaten to remove dust, as they may have accumulated radon decay products.

• Sealing of floor and wall openings

Radon does not pass through the full thickness of concrete immediately, it seeks easy pathways. Inspect the floor and corners for cracks and gaps, and fill these openings with silicone sealant, acrylic or expanding foam. If the floor is earthen, cover it as tightly as possible with a thick double layer of polyethylene film, sealing the joints with tape. This is a temporary but effective barrier.

• Use of sorbents and air purifiers

Although standard HEPA filters do not trap radon itself (as it is a gas), they capture radon daughter decay products that attach to dust particles. This partially reduces the risk.

• Monitoring the effectiveness of implemented anti-radon measures

To verify the safety of the premises, conduct radon measurements, analyze the results and assess radon exposure risks, and obtain advice on reducing radon concentration, contact the SSTC NRS Testing Center.

Conclusion

Radon can indeed accumulate in closed basement spaces. However, the risk of brief exposure during an air raid alert is significantly lower than the risk of direct injury during shelling. Radon is a long-term exposure factor, while shelling poses an immediate mortal threat.

The war forces us to choose between protection from shelling and protection from radiation. We cannot avoid shelters, but we can reduce radon exposure and this does not require complex or costly solutions. Regular ventilation, ensuring at least minimal air circulation, sealing cracks in floors and walls, and basic radiation monitoring can significantly reduce radon concentrations in shelters.

During shelling, shelters protect from blast waves, debris and structural collapse, and are often the only chance to survive. Refusing to use shelters out of concern about radon is far more dangerous than staying in them.

References:

1. WHO Handbook on Indoor Radon: Public Health Approach
2.  U.S. Environmental Protection Agency (EPA) Guide to Protecting Yourself and Your Family from Radon
3.  Overview of Radon Policy in Nordic Countries
4.  Strategy for Reduction of Radon Exposure in Norway

Editorial Board of Uatom.org