Hospitals are failing to crack down on smoking on their premises, according to a new report.
A survey of 140 hospitals for the British Thoracic Society found that only one in 16 fully enforced a no-smoking policy.
Enforcement includes giving people information on the trust's smoke-free policy, as well as policing hospital grounds and putting up signs.
Some 40% of hospitals had designated smoking areas - such as a shelter - while the other 60% described their entire premises as smoke-free.
The report found that NHS hospitals across UK are falling short of measures to help patients, staff and visitors quit. Included in the analysis were 14,750 patient records.
The study found that 72% of hospital patients who smoked were not asked if they would like to stop.
Just 8% of hospital patients who smoked were referred for hospital or community treatment to help them quit, while 27% were never even asked if they smoked.
The investigation also found that just 26% of hospitals had a consultant overseeing their smoke-free and stop smoking plans. Half of staff were also not offered training in helping people to quit.
Dr Sanjay Agrawal, consultant lung specialist and chairman of the British Thoracic Society's Tobacco Group, who led the audit, said: "Our report shows that many NHS hospitals are woefully failing to meet national guidance on delivering smoking cessation services and smoke-free premises.
"This is a dangerous situation that is costing the country dear in both health and economic terms. We must do better.
"Critically, hospitals are missing out on a golden opportunity to help supply often the most effective treatment for illnesses that smokers are admitted with – support and treatment for their tobacco dependence.
"If patients in other disease areas were not offered, by default, the most effective way to treat their condition, there would probably be an uproar. Nevertheless, this happens all too frequently with people with smoking-related illnesses."
Dr Penny Woods, chief executive of the British Lung Foundation, said: "It is deeply concerning that hospitals – the places you'd expect to be most committed to helping patients to stop smoking – are in many cases failing to do this. Personal support and advice from a clinician is vital when it comes to helping someone to quit.
"Smoking tobacco is the biggest avoidable cause of death. On average, smokers live 10 years less than non-smokers. Hospitals must get their act together."
Deborah Arnott, chief executive of health charity Ash, said: "Every year thousands of people across the UK are admitted to hospital to be treated for diseases such as heart disease, cancer and respiratory disorders caused by smoking.
"Given the scale of the harm caused by smoking, it's shocking that more is not being done in hospitals to support patients to quit."
Duncan Selbie, chief executive of Public Health England, said: "We want to see a truly tobacco-free NHS where every hospital's buildings and grounds are completely smoke-free.
"A quarter of patients in hospital are smokers. I believe we can make the NHS a place that provides a supportive tobacco-free environment for patients, staff and visitors, where helping people quit is fully integrated into their treatment."
Simon Clark, director of the smokers' group Forest, said: "It's quite wrong to put smokers under pressure to quit when they are in hospital, especially if the reason they are there is not smoking-related.
"Being in hospital can be extremely stressful and having a cigarette is a source of comfort to many smokers.
"Enforcing smoke-free premises is a cruel and unfair way to treat patients who smoke.
"Nagging them to quit when they are at their most vulnerable also demonstrates a worrying lack of empathy.
"This is the opposite of health care. In the name of public health, compassion is being replaced by zealotry and intolerance."