To mark the five year anniversary of the launch of London Underground's 'spit kits', a Tube worker has been recounting some unpleasant episodes.
Jill Wilson, 45, a customer service assistant at Uxbridge Tube station was spat at in the face by a 17-year-old from Hayes earlier this year.
She had asked the teenager to leave the station after he attempted to get on to the platform without paying.
She said: "It's bad enough to be spat at but it's even worse when it lands in your face. I'm sure that for most people the thought alone would make them feel queasy."
After being abusive and then assaulting Ms Wilson the teenager ran off.
But after using a spit kit, which provides sterile storage for saliva samples, the teenager was tracked down using DNA from his saliva and charged with common assault.
He was given a two year community rehabilitation order and a six month curfew.
Ms Wilson added: "What he did, it didn't frighten me. It just made me sick that someone could be so disgusting.
"It was a big relief when I was told he was caught."