Kingswood School, an independent co-educational day and boarding school in Bath, has been fined £50,000 after exposing seven children and two staff members to high levels of radioactive radon gas, Yahoo News has reported.

Five pupils were exposed to levels of radon almost eight times the legal limit, while boarding in 2019 and two children of staff who lived on site were exposed to levels almost 14 times the limit, while their parents were also reportedly exposed to high levels.

Radon gas is the second-largest cause of lung cancer in the UK, resulting in more than 1,000 fatal cancers each year according to the Health and Safety Executive. The colourless, odourless substance is found in rocks and soils, as well as some building materials and water. It can seep out of the ground and build up in houses and indoor spaces such as schools. Bath is an area known as a “radon affected area”.

Laws are in place to limit exposure to radiation in the workplace and the HSE says employers in such areas should engage specialist contractors to measure radon and ensure it stays at an acceptable level.

An HSE investigation found Kingswood School “knew [it] had a radon problem as far back as 2007”, when the school carried out monitoring and introduced measures to reduce radon levels.

The HSE stated: “However, from 2010 to 2018 the school carried out no subsequent radon monitoring and had no systems in place to ensure radon control measures were adequate. Only following HSE intervention in 2018 did the school find out about their previous radon problem and further radon monitoring and remediation was carried out to reduce radon levels.”

Kingswood School Trustees Limited pleaded guilty to breaching Section 2(1) and 3(1) of the Health and Safety at Work etc Act 1974. The school was fined £50,000 and ordered to pay £19,222 costs at Taunton Magistrates’ Court.

A schools spokesperson said: “While the overwhelming majority of our school has radon levels that are similar to those across the rest of Bath, because of our location, we have a small area of our school where radon levels can exceed the minimum standards.

“To address this, in 2010 a number of measures were installed in a small number of areas to mitigate the risk of higher than average radon levels. Regrettably, however, after the installation of these devices, the school did not adequately monitor and record radon levels between 2010 and 2019.

“As a result of this, the HSE has fined the school £50,000. We wholly accept this ruling and, at the court hearing, the judge acknowledged the genuine remorse shown by Kingswood in response to these historic failings. It is important to note that both the prosecution and the judge accepted that the risk of harm from this failure was low.

“We are sorry that we have fallen short in the management of this important element. Over the last four years we have already made many additional changes to ensure that our radon mitigation, monitoring and recording far exceeds recommended standards. We will continue to work with leading experts in the field to provide additional expertise and assurance.”