The union’s research found that nearly a quarter (22%) of those who had experienced harassment in the past year had been sexually assaulted, including rape, up-skirting, indecent exposure and inappropriate touching.
Most of the victims were women (81%) and the perpetrators were mostly colleagues and other workers, although 42% reported being harassed by patients.
When the abuse was committed by a member of staff, the offender was normally older than their target and more than a third were employed in a more senior role.
For nearly a third of victims, harassment was a regular occurrence and 12% said it was as frequent as weekly or daily, with verbal abuse the most common type of harassment experienced.
The impact of harassment on the targets has been significant, with more than half saying they would isolate themselves or avoid particular colleagues or situations, over a third saying it affected their mental wellbeing, and 40% thinking about leaving their jobs.
But despite this, most victims kept quiet about the abuse they were experiencing, with the most common reason being that they did not believe reporting their harassment would not result in action being taken and some concerned it could make the situation worse.
Assistant General Secretary of Unison, Christina McAnea, said: “Staff should never have to face any kind of abuse, let alone sexually motivated insults and attacks … The workplace which should be a harassment-free zone and employers who fail to act should be held to account.”
The union called for the government to hold employers accountable for protecting their staff from third parties, such as contractors and patients – a change in the law the Institute of Employment Rights has recommended in its Manifesto for Labour Law.