The tritium present in the environment today is partly of cosmogenic and partly of artificial origin. "Cosmogenic" means that the tritium is produced by particle radiation from space in the Earth's atmosphere. The atmospheric nuclear weapons tests of the 1950s and 1960s are the main source of the artificial tritium content.

The caesium-137 regularly detected in precipitation largely originates from the Chernobyl reactor accident. In 2023, 12 measured values were above the detection limit. The highest measured value was 0.15 Bq/m² (Salzburg, July 2023), the median was 0.03 Bq/m². The measured values were thus within the range of recent years.

No health-relevant values were detected.

The samples are generally taken monthly as random samples. In addition, some rivers are sampled using automatic collection devices. These are used to take samples at regular intervals over the course of a month, which are then combined to form a total sample. This comes very close to continuous sampling. Surface water is sampled at 19 locations in all federal states throughout Austria (see chart). In 2023, a total of 286 surface water samples were collected and analysed.

Elevated tritium concentrations have been detected at the sampling point on the Thaya in Bernhardsthal since around mid-1985. No elevated tritium levels have been recorded at the upstream sampling point in Alt-Prerau. After Alt-Prerau, the Thaya leaves Austria and flows through Czech territory as far as Bernhardsthal. There it is fed by the Jihlava River, on the upper reaches of which the Dukovany nuclear power plant is located. The origin of the tritium is therefore assumed to be in the Czech Republic.

Elevated tritium levels have also been found in the Morava, into which the Dyje flows, since 1985. Due to the increasing dilution with water from tributaries, the tritium concentrations decrease downstream.

The activities of the radionuclides regularly found in surface waters corresponded to the long-term average. No values relevant to health were detected.

Wastewater and sewage sludge from wastewater treatment plants can provide information about the radionuclides contained in wastewater from businesses, medical facilities, research institutions, households, etc.

For example, radionuclides are detected in these samples that are used in nuclear medicine for diagnostic and therapeutic purposes and mainly enter wastewater treatment plants via patient excretions, such as gallium-67, iodine-123, iodine-131, indium-111, lutetium-177, technetium-99m, thallium-201 and thallium-202. Every year, around 130 samples are collected and analysed to monitor wastewater treatment plants.

Animal feed is an important part of the food chain and can have an influence on the radionuclide content in food. For this reason, they are regularly analysed by AGES as part of laboratory-based environmental monitoring.

Samples are taken at random and around 50 samples of feed from different feed classes are analysed each year. These include, for example, vitamins and minerals.

By monitoring air, precipitation, surface water, sewage treatment plants and animal feed, we can also detect minor increases in radioactivity in the environment and report these immediately to the responsible federal ministry. If conspicuous measured values occur, these are exchanged within the European and international framework via the EU and the IAEA (International Atomic Energy Agency, International Atomic Energy Organisation) and the population is informed. In addition, radioactivity laboratories around the world are in direct contact with each other and exchange information.

Further details on environmental and food monitoring in Austria can be found in our joint report with the Ministries for Climate Protection and Health. The reports can be found under Downloads.

Harmful substances such as heavy metals and radioactive substances can accumulate in wood ash, although the amount can vary greatly. The accumulation of radioactive substances is highest in wood pellet ash. For this reason, among others, wood pellet ash should not be used to fertilise the garden.

Wood is a relatively fast-growing raw material and is considered an environmentally friendly,_CO2-neutralfuel. The combustion process only produces ash as a waste product. There are specially designed combustion systems for the respective wood fuel (wood pellets, wood chips, logs and wood briquettes), which are optimally adapted to the product used.

Heating with wood pellets is subsidised by the federal government, the federal states and the municipalities. In recent years, more and more households have been heating with pellet boilers. Nationwide, there are more pellet boilers than other biomass boilers . In Austria, only by-products from the sawmill industry and no bark are used for pellet production. During heating, the organic component of the wood is burnt, while the mineral, non-combustible part remains as ash. Plant ashes from biomass furnaces can be valuable secondary raw materials. Their possible use on agricultural and forestry land is described in more detail in the "Guideline for the proper use of plant ashes". This can be found at the bottom of this page under Downloads.

As a result of the Chernobyl reactor accident (1986), among other things, radioactive caesium and strontium were spread across several European countries, including Austria. These radioactive substances are absorbed by vegetation. Due to their half-life of around 30 years, radioactive caesium and str ontium can still be detected in plants (e.g. trees) and wild animals in the affected areas. If wood from these regions is used for heating, radioactive caesium and strontium can accumulate in the ashes.

The radioactivity in the wood itself is harmless from a radiation protection point of view and therefore poses no health risk to the population. However, the accumulation of radioactive substances in the wood ash produced varies greatly and can be relevant from a radiation protection perspective.

However, we do not recommend scattering the wood pellet ash in the garden or even on a vegetable patch. This is because, in addition to radioactive substances, the ashes also contain concentrations of non-combustible and potentially harmful minerals, salts, heavy metals and organic pollutants.

The disposal of ashes in private households is regulated differently in each federal state and often also in each municipality. In most of Austria, it is mandatory to dispose of the cooled ash in the residual waste.

Detailed technical information on the project can be found in the final report, which can be downloaded here.