Parents should be seeking to find out whether their children's school contains asbestos now deaths from the disease are rising, teachers claim today.
Figures show the number of UK teachers dying from mesothelioma has risen to 22 a year - the highest rate in the world. This is up from just three in 1980.
In addition, expert advice given to the Commons select committee on education estimate up to 300 former pupils a year die of the disease through contact with asbestos at school.
Today delegates at the National Union of Teachers' conference in Harrogate will debate a motion expressing concern that the UK has te highest and still rising incidence of mesothelioma in the world.
Sarah Lyons, the union's expert on asbestos, said a Freedom of Information request to local authorities had indicated 86 per cent of existing schools contained asbestos. Those most likely to be affected would have been built post 1945 and before 1975 - but its use was only phased out in 1999.
However, many teachers are unaware as to whether their schools contain asbestos - with 44 per cent of teachers surveyed saying they had not been told whether their school contained it.
One teacher told researchers: "The first I knew about it was when a caretaker came into my room with a pot and paintbrush and when I said 'oh, I didn't know my room was being decorated' he answered 'it's not - I'm sealing the asbestos panels'."
Another added: "The door to my laboratory has an exposed asbestos lining. I stood at the door at the start and every lesson for 10 years, greeting students, before someone pointed out to me that the asbestos surface had been broken."
Ms Lyons said parents should ask their schools about the situation, adding: "We wouldn't want to cause pain or anything but it is a question that should be asked.
"We're equally concerned about teachers and support staff but the dangers for children can be more acute because they've got more life ahead of them."
Kevin Courtney, deputy general secretary of the NUT, said former pupils were dying 30 or 40 years after having contact with the asbestos.
Christine Blower, its general secretary, added: "Political parties must actively engage with a problem which is very far from being addressed and has taken many lives. Children, parents and staff deserve better."