As campaigners cheer a total smoking ban, there are fears sending smokers outside will lead to a huge increase in greenhouse gas-emitting patio heaters.
Patio heaters allow people to eat, drink and smoke outside
Labour MP Stephen Pound said when he visited Ireland recently - where a smoking ban is already in force - pub gardens were "covered" in the heaters.
Britain's greenhouse gas emissions are already up by 380,000 tonnes a year due to such devices, it is claimed.
Lib Dem Norman Baker advised smokers to "enjoy the bracing air" instead.
The BBC's environment correspondent Roger Harrabin said patio heaters have become a "beacon of aspiration" for those keen on enjoying outdoor dining, in the UK's unpredictable climate.
During Tuesday's smoking debate in the Commons Ealing North MP Mr Pound told members of his recent trip to Temple Bar area of Dublin, where a smoking ban in public places is already in force.
"What an extraordinary sight greeted me when, with a number of my Parliamentary colleagues and several members of the Dail, I visited a number of pubs to find that all of them fell into one or other of two categories.
"Either the entire perimeter area was covered with patio heaters and armchairs so that anybody who wanted to go into the admittedly smoke-free pub had to fight their way through a tangible fug of nicotine-soaked air to get into the damned place in the first place, which makes something of a nonsense of it," said Mr Pound, who has vowed to give up smoking following the ban vote.
Health campaigners have welcomed a vote paving the way for a ban on smoking in all pubs, clubs and restaurants in England, which will come into effect from the summer of 2007 following a free vote by MPs.
But the increased use of patio heaters is also of growing concern to some politicians.
Labour's Desmond Turner, MP for Brighton Kemptown, wants to ban them completely, calling them a "waste of energy".
He told BBC Radio 4's Today programme: "The use of patio heaters accounts for about one million tonnes of CO2 emissions a year, which immediately cancels out, for instance, the savings made by government changes to vehicle taxations."
Liberal Democrat environment spokesman Norman Baker agreed that patio heaters were a "waste of resources" and "doomed to failure".
He told the BBC News website: "If I see patio heaters I try to make the point in a barbed comment to the person using it.
"I'm not against people smoking outside, it's better than them smoking inside, but I think they should enjoy the bracing air around them."
He later said the government should establish an effective strategy, such as selling patio heaters with "health warning" style labels.
"Patio heaters are an absurd invention. It is ludicrous that people are trying to heat the open air, as well as being irresponsible in the light of the climate change challenge we face.
"Instead of reaching for the gas canister people should reach for another jumper instead," he added.
Parliamentary questions by Mr Baker have revealed Britain's greenhouse gas emissions are up by 380,000 tonnes a year due to patio heaters.
Using a patio heater for two hours produces the same amount of carbon dioxide as a car produces in an average day, it is claimed.
But smokers' campaign group Forest hit back. Director Simon Clark said any notion of banning patio heaters was "barking mad".
He said the moved smacked of "petty vindictiveness" towards smokers.
"Is it that these MPs simply do not like the idea that smokers might be moderately comfortable smoking outdoors?" he asked.
He said the damage to the environment from patio heaters was "minuscule" in terms of the overall effect.