More than two-thirds of workers could be at risk from potentially dangerous hazardous substances, research has found.
According to a study of 500 people, 71% were exposed to, or at risk from, substances which could harm their health - such as hazardous chemicals and gases, radiation sources and biological agents such as bacteria, fungi, viruses and other pathogens.
The survey was carried out by the TUC to mark Worker's Memorial Day on 28 April. It also falls days after the second anniversary of the Rana Plaza factory collapse in Bangladesh, in which almost 1,200 workers lost their lives.
TUC general secretary Frances O'Grady said: "The people who completed our questionnaire are a reminder that many workers in the UK are exposed to a range of hazardous substances. For some it is on a daily basis, and the result has been thousands of deaths and hundreds of thousands of people suffering ill-health.
"Yet every single one of these cases could be prevented. Many of these substances could be removed from the workplace or their use reduced - but where this is not possible, workers need much better protection. That means stronger regulation, and, more importantly, proper enforcement."
"On International Workers' Memorial Day in workplaces across the world and in the UK, trade union health and safety representatives will consider what can be done to stop unnecessary deaths, injuries and illness," added O'Grady.
"We need employers and governments to do more too.
"The appalling loss of life that resulted from the Rana Plaza collapse shows just what can happen when workers do not get the health and safety protection they need at work. It was a tragic reminder that complacency about health and safety is deadly."
Events will be held across the UK today, including wreath laying at the building workers statue at the Tower of London.
Jerry Swain, of the building workers' union Ucatt, said: "This is a day to be both sombre and angry. As well as campaigning about site deaths, we need to target the invisible killer caused by occupational disease. Thousands of construction workers die prematurely every year because their employers needlessly exposed them to dangerous substances."