In the Netherlands, the concentration of radon in most homes and buildings is low. This is due to the composition of the soil. In a number of particular workplaces, such as in marl quarry caves and at drinking water companies, the concentration of radon in the air may be higher. In these workplaces, the exposure of employees to radon may be higher than in others. This is the outcome of a study conducted by RIVM. The Ministry of Social Affairs and Employment may decide that additional measures must be taken in such workplaces.
What is radon?
Radon is a radioactive gas that is naturally released from the soil and from soil materials, such as construction materials or ground water. If high levels of radon are released in a poorly ventilated area, the radon concentration may become high. People who are exposed to high radon concentrations for many years run a higher risk of developing lung cancer. This risk is higher for smokers than for non-smokers.
What did the RIVM study involve?
RIVM measured the radon concentrations in seven marl quarry caves in South Limburg and at 65 production stations for drinking water purification. In caves, radon is released naturally and there is little ventilation. At production stations, radon is released during the water purification process. RIVM then compared the measured values with the reference level. This is the level that the measured values should exceed as little as possible. Lastly, RIVM made an estimate of the level of exposure of employees to radon. The elevated radon concentrations in marl quarry caves have no consequences for visitors. Furthermore, tap water is safe to drink.
What were the results?
In almost all the investigated marl quarry caves, the measured concentrations exceeded the reference level. This was the case for around a third of measured concentrations at drinking water companies. Employees do not usually spend all of their working hours at locations where high radon concentrations were found. For example, they give guided tours in the caves or carry out maintenance at the production stations. It follows that the exposure of most employees to radon is estimated to be low.
However, the exposure of nearly 30% of employees was relatively high – in other words, higher than it would be if they worked fulltime at the reference level. Their exposure was comparable to that of employees who are exposed to radiation from other sources through other occupations, such as hospital staff or pilots.
What can the government do?
European Member States are required to have a radon action plan in place in order to reduce the negative health effects as much as possible. In the action plan, the Ministry of Social Affairs and Employment can designate marl quarry caves and drinking water companies as ‘specific workplaces’ and impose measures for those workplaces. If the concentration exceeds the reference level, the employer must investigate how the exposure of workers can be reduced.
Reason for this study
RIVM conducted this study at the request of the Ministry of Social Affairs and Employment. RIVM conducted the first radon measurements in workplaces in 2016. The results showed a need for a further study in marl quarry caves and at drinking water stations. This report describes the results of that further study. Additional research may be required, as measurements have not yet been conducted at all locations. Other subjects for additional research include the exposure of individual employees or ways to reduce exposure.