Millions of people may still be working in buildings which contain asbestos even though it is a banned substance, according to a report.
Chest x-rays can identify if someone was exposed to asbestos
The TUC claims that many employers are unaware of their legal obligation to find out about asbestos and said 1.5 million workplaces could be affected.
New research showed that 4,000 people were dying each year in the UK from asbestos-related disease.
Leaflets warning of the dangers are being sent to offices and factories.
Brendan Barber, TUC general secretary, said: "All forms of asbestos are dangerous, no matter what some employers might say.
"The cancers caused by the killer fibres can take years to develop, so someone who breathes in asbestos dust now may not become ill for another 25 years.
"We don't want to see any more people exposed to asbestos in future."
A million stickers and thousands of leaflets will be sent to workplaces, bearing the message: "Asbestos Kills."
Within the next decade, asbestos-related diseases will account for 10,000 deaths a year, the TUC estimates.
Asbestos diseases are caused by inhaling asbestos dust, a mineral commonly used in the construction industry until the 1970s.