Leading health experts have called for smoking to be banned in outdoor public spaces such as parks.
Writing in the British Medical Journal, former Labour Health Minister Lord Darzi and others argue it would encourage people to make healthier lifestyle choices.
But in the same journal, Prof Simon Chapman of the University of Sydney called the idea "paternalistic".
The UK smoking ban introduced in 2007 covers indoor public spaces.
But Lord Darzi and Dr Oliver Keown - both based at Imperial College London - argue it should now be extended to include parks and squares.
Despite outcry over what some considered an attack on public freedom, smoking rates have fallen and attitudes to this type of measure are changing, they say.
And they give the example of New York City, where a ban in workplaces and recreational areas was extended in 2011 to cover public spaces including parks, squares and beaches.
Lord Darzi says policies need to move forward from offering potential protection from passive smoking to consider opportunities for behaviour change,
He suggests that reducing the chance of young people seeing others light up would make smoking behaviour appear less of a norm.
An extended ban would be an opportunity to celebrate healthy living, clean air and the physical activity green spaces are meant for, he argues.
But Prof Chapman says the 2007 indoor smoking ban focused on evidence of the harms of passive smoking in indoor spaces or workplaces over long periods of time.
In contrast "fleeting encounters with cigarette plumes" in wide open spaces pose "a near homeopathic level of risk to others", he says.
He suggests the relative lack of research looking specifically at the impact of lighting up cigarettes in parks and on beaches is down to scientists appreciating that such exposures "would be so small, dissipated and transitory as to be of no concern".
Prof Chapman says policies based on mere sightings of smokers are "redolent of totalitarian regimes in their penchants for repressing various liberties."
He asks: "Why not extend the same reasoning to drinkers or to people wolfing down supersized orders in fast food outlets?"
Simon Clark, director of the smokers' group Forest, said: "Tobacco is a legal product and smokers pay £10bn a year in tobacco taxation alone.
"As long as they are considerate to those around them they must be allowed to light up outside without being harassed or made to feel uncomfortable.
"We must be careful we don't create a world only puritans can inhabit."
Councillor Izzi Seccombe of the Local Government Association, said: "Local authorities are already running a wide range of innovative schemes to help people stub out smoking. But they have a limited health budget with competing priorities.
"By putting some of the existing tobacco duty to better use, we could do so much more.
"This is why we are calling on government to help people live healthier lives and tackle the harm caused by tobacco by reinvesting a fifth of existing duty raised on cigarettes."