Doctors in the UK have issued advice to acid attack witnesses on the "important role" they can play in helping victims.
An intervention by bystanders could "substantially improve the outcome", senior figures from the Royal College of Emergency Medicine (RCEM) and Barts Health NHS Trust said.
They wrote in the British Medical Journal that contaminated clothing should be removed, before pouring copious amounts of water over the affected area to minimise the risk of scarring and need for plastic surgery.
Public education was needed, they added, to tackle "the latest menace on our streets".
There have been 400 acid attacks in Britain in the six months leading up to April.
"Already 2017 has seen a big increase in acid attacks in the UK, relative to 2016," the medics said.
"Whereas in the past most of the attacks were related to robberies, corrosive substances now seem to be a replacement for carrying knives."
In the moments after an acid attack, bystander #firstaid can make all the difference. Here's our advice on how to help someone who needs it. pic.twitter.com/09zUUQWH25
— London Ambulance (@Ldn_Ambulance) August 3, 2017
Police have released footage of suspects shortly after an attack on Monday near Harrods department store in London, where a pedestrian was attacked with an unknown liquid.
The 47-year-old victim was treated for minor injuries and has been discharged from hospital.
Johann Grundlingh, an emergency consultant at Barts who co-authored the report, said most people understood the need to use water, but few realise how much is required.
He said: "I think there's an inherent reaction to when you see someone with a burn to put water on it, or something cold on it least.
"Definitely the people I've encountered on the street who have been attacked want to wash off what they've been attacked with.
"But a small 350ml bottle of water is not going to help. It's the volume of water that is necessary and that people don't know about and we encourage people to use litres and litres of water."
Mr Grundlingh said between 40 and 60 litres being poured over the burn to dilute the acid would give a victim the "best chance" of escaping long-term injury.
People should run into corner shops and ask for bottled water or to use a tap, he added.
British MPs have debated tougher measures to deal with the rising number of attacks, a large proportion of which have taken place in east London.
