Londonderry radon gas levels high in three schools
Work has been carried out at three primary schools in Londonderry to reduce levels of a radioactive gas which can cause cancer.
The Western Education Board confirmed it had fitted extraction systems in July after unacceptable levels of Radon were found in the schools.
The board has refused to identify the schools involved, but said they were being monitored.
Radon emits radiation from the ground and has been linked to lung cancer.
It is a naturally occurring, colourless, odourless, radioactive gas found at varying levels in all houses in the UK and across Europe.
People who are exposed to high levels of Radon are more likely to get lung cancer, especially if they are smokers as well.