CBRN event in United Kingdom on Tue 31st December 2019

The incident occurred at a private boarding school where pupils, employees and their children had been exposed to high levels of radon gas in the atmosphere. 

The two employees and their two children were exposed to the high radon gas levels as a result of working and living at the school. The five overexposed pupils studied and lived at the school during this time.

An investigation by the regulator (Health and Safety Executive) found that the school knew they had a radon problem as far back as 2007 when they carried out monitoring and installed some remediation to reduce radon levels. 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 an intervention by the regulator in 2018 did the school find out about their previous radon problem when further radon monitoring and remediation was subsequently carried out to reduce radon levels.

Dose estimations were made based on expected occupancy times for the individuals for that year, these were as follows: 

Employee 1 : 15mSv
Employee 2 : 15mSv
Employees child 1 (member of the public): 14mSv
Employees child 2 (member of the public): 14mSv
Pupil 1: (member of the public): 8mSv 
Pupil 2: (member of the public): 8mSv 
Pupil 3: (member of the public): 8mSv 
Pupil 4: (member of the public): 8mSv 
Pupil 5: (member of the public): 8mSv 

The annual effective dose limit in the UK for employees is 20mSv and for members of the public is 1mSv.