Why and how is radon measured? Senate conducted an extensive study of radon levels in workplaces
5 min
Senate has measured radon levels in almost 300 state-owned buildings. Radon measurements at workplaces are part of occupational health and safety and by law employers are responsible for establishing radon levels. Senate carried out the study itself in accordance with its zero tolerance policy. Risse Koponen, Indoor Climate Specialist at Senate Properties, tells about the implementation, results and measures of an extensive study.
In 2020, Senate studied radon levels in no less than 297 state-owned buildings where work is done at least 20 hours a year or six minutes a day. The oldest buildings studied dated from the 1800s and the newest were from 2019.
The zero tolerance for poor indoor air conditions announced by Senate includes preventive monitoring of radon levels in a building. An extensive report compiled of last year’s radon reports based on which measures are being planned to eliminate any radon harm.
Risse Koponen, Indoor Climate Specialist at Senate Properties, tells us what is good to know about radon and its study in the workplace.
Risse Koponen, Indoor Climate Specialist at Senate Properties.
What is radon and why do its levels need to be monitored?
Radon is an odourless, tasteless and invisible radioactive gas formed from uranium deep inside the earth. Radon migrates into the indoor air through gaps in the base floor of buildings. Radon in the indoor air is the most significant source of radioactive radiation for Finns.
There is a lot of radon in the soil in Finland and there are many places in the country where radon measurement in workplaces is mandatory. Radon levels may not exceed 300 becquerels per cubic metre (Bq/m³) in a workplace where more than 600 hours are spent working each year.
How is radon radiation measured?
Radon investigation is carried out very simply. Measurements are made using alpha track detectors approved by the Radiation and Nuclear Safety Authority STUK and which are taken into workplaces and affixed to a quiet place. The detectors are left in the measuring points for around 2-4 months before the samples are analysed by an accredited laboratory.
Where the measurement result exceeds 200 becquerels per cubic metre, we immediately clarify whether the employees spend over or below 600 hours working there a year. In addition, we also investigate the diurnal variation in the radon level.
Measurements are carried out using alpha track detectors approved by the Radiation and Nuclear Safety Authority STUK.
Is radon a problem in old buildings?
Studies show that radon levels can’t be determined based on the age of a building. Nor does the result of a building inspection reveal the radon risk directly but damage and air leaks in the base floor indicate an increased risk for occurrence of other problems with indoor conditions as well. Radon measurements should always be done in those buildings where inspection has found there to be defects in the base floor structures.
Was radon found in state-owned buildings?
The situation is quite good in those state-owned buildings inspected: the average radon level was 73 becquerels per cubic metre. This is considerably less than the average level of 94 becquerels per cubic metre found in Finnish dwellings.
In those some thirty buildings where the reference values of 300 Bq/m3 were exceeded, measures have been initiated and the matter has been communicated to the users of the premises concerned.
A building was classified as a radon risk building if one of the radon measurement results exceeded 200 becquerels per cubic metre and more than 600 hours a year were spent working in the workplace. These buildings have accounted for fewer than 20% of the buildings inspected. In radon risk buildings there is a possibility that the reference level for occupational exposure will be exceeded in the event of changes to the use or conditions of the building. Where increased use of the space is required, the need for radon repairs must be re-assessed.
An alpha track detector is taken into workplaces and affixed to a quiet place. The detector is left in the measuring point for around 2-4 months before being sent for analysis by an accredited laboratory.
How do people working in Senate premises know about radon quantities?
The aim of the 2018 reformed Radiation Act is that no one in Finland should be overexposed to radon gas in their work. Radon measurements in workplaces are part of occupational health and safety of staff and facilities users. By law, the employer is responsible for investigating radon levels.
The zero tolerance for poor indoor conditions announced by Senate Properties is based strongly on pro-active work, which is why the indoor air team inspects and investigates the radon levels of buildings on its own initiative. When radon levels have been measured in Senate premises, the property manager reviews the results with the employer and staff. Senate ensures any repairs and follow-up measures based on the investigation results.
How does Senate monitor radon radiation in buildings?
We have already developed new practices based on investigation results. For example, we recommend radon piping for all large newbuild and repair projects going forward to prevent radon from migrating from the soil into the indoor air. Radon piping also helps to improve the moisture-technical functionality of the base floor.
We will continue to monitor radon levels pro-actively in state-owned buildings. Radon investigations will be added systematically to the annual inspections of buildings. This will help us to collect knowledge-based information about any changes in radon levels so that we can respond and better investigate the reasons for them.
Senate classifies radon results into five different categories, where in addition to radon level the restrictions on use of the facilities is taken into account. This is useful where there are later changes in the purpose or use of the premises.
