Smoking rates across the UK continue to fall, with a sharp decline since 2010 among younger people, figures show.
In 2016, 15.8% of adults in the UK smoked, down from 17.2% in 2015, the data from the Office for National Statistics (ONS) showed.
Some 15.5% of adults currently smoke in England, rising to 18.1% in Northern Ireland, 17.7% in Scotland and 16.9% in Wales.
Across the UK, 5.6% of people - around 2.9 million - used e-cigarettes in 2016.
Duncan Selbie, chief executive of Public Health England, said there were now more than half a million fewer smokers in England than in 2015.
He said the UK now has the second lowest smoking rates in Europe after Sweden.
He added: "What is really fantastic news is that this steep decline is even greater among young adults (aged 18 to 24), where smoking has fallen by a staggering quarter since 2010, reversing a long trend."
In 2010, 26% of this age group smoked, dropping to 19% in 2016.
Mr Selbie said: "It's now hard to believe that back in 1974 almost half of adults smoked. But now an end really is in sight and we have a real opportunity to virtually eliminate all the harm, misery and death caused by smoking."
Dr Penny Woods, chief executive of the British Lung Foundation, said: "People who quit live longer and feel better, no matter their age. However we must not be complacent. Smoking is still the UK's biggest cause of early preventable death.
"Approximately 100,000 people die needlessly from smoking-related diseases every year in our hospitals - it's time to tackle the human and financial cost the tobacco industry creates.
"These statistics confirm that e-cigarettes are mainly being used to help people quit. Given half of long-term smokers die as a result of their habit, using vaping to help someone stop smoking could literally save their life.
"A new tobacco control plan was expected to be published last year. It is now well overdue, and must be a priority for the new Government."
Ash chief executive Deborah Arnott said: "One in two lifetime smokers will die from smoking-related disease, so a fall in smoking rates of this scale will save many thousands of lives in years to come.
"This proves that tobacco control policies work when they are part of a comprehensive strategy and are properly funded."
Smoking rates among pregnant women have dropped slightly, with around one in 10 smoking in pregnancy.
Sarah Fox, professional policy adviser at the Royal College of Midwives, said: "These are encouraging figures and we need to see this downward trend continue.
"Smoking is one of the main contributors to stillbirths and if we can reduce the numbers smoking in pregnancy even further we can make a contribution to reducing stillbirth rates."