Lethal asbestos is present in 70,000 Housing Executive homes in Northern Ireland
Almost 70,000 Housing Executive properties in Northern Ireland have asbestos.
The cancer-causing fibres are present in nearly three-quarters of dwellings, figures have revealed.
The details emerged after a Freedom of Information request by online blog Beyond the Pillars. Asbestos was used extensively as a building material between the 1950s and mid-1980s.
It is now banned, but remains in many schools, hospitals, offices and factories.
It becomes dangerous when disturbed and, if inhaled, its fibres can cause lung problems such as the fatal mesothelioma and debilitating asbestosis.
Every year around 4,000 people die from mesothelioma and asbestos-related lung cancer across the UK.
Beyond the Pillars found asbestos is present in 69,747 Housing Executive properties across Northern Ireland.
That is equivalent to 71.43% of the Housing Executive's 98,000 stock.
Graham Dring from the Asbestos Victims' Support Groups Forum UK said asbestos was a common problem for housing associations.
"We do know there are issues with asbestos in a lot of local authority housing," he said. "It was widely used, particularly in post-war housing, continuing into the Sixties, Seventies and Eighties.
"The long-term policy has got to be getting asbestos out of properties.
"Things like fires or accidental damage in any building containing asbestos carry the risk of exposure to tenants and their families.
"Therefore it is best to eradicate asbestos from the properties, although we recognise this cannot happen overnight."
The Housing Executive said asbestos had been treated at 1,397 properties since 2011 at a cost of £297,863. The highest number of properties is in the Coleraine area - 198 at a cost of £33,224
In south Belfast a further £33,420 was spent treating 175 properties.
A Housing Executive spokesperson said: "The Housing Executive has a programme in place to manage asbestos in all of its properties. As part of that, we inspect all of our properties.
"We advise all of our tenants of the process and what happens if asbestos is found and if any action is required. This also includes advice around house sales and home improvements.
"We would stress that the asbestos in the majority of our properties is low-risk, i.e. it is present in floor or roof tiles, soffits etc. Asbestos only poses a risk if it is disturbed.
"Our tenants are advised that they should not be making changes to their properties without approval from the Housing Executive, at which stage we will check if asbestos survey details are available. If not, we will acquire a survey relevant to the works
"All our surveys are risk-assessed and asbestos is only removed when it is deemed likely to cause a risk to the occupants or any other visitor."