Ireland became the first country in the world to outlaw cigarettes in all its restaurants and pubs on Monday, to the delight of non-smokers but the dismay of some publicans worried about having to police the ban.
From midnight on Sunday it became illegal to smoke in virtually all workplaces, closed public spaces and on public transport, with fines of up to 3,000 euros ($3,825) for transgressors.
While similar bans have been imposed in cities and states elsewhere in the world, including in California and New York, Ireland is the first country to impose such a ban nationally.
Sheila Montgomery, a non-smoking office worker welcomed the new law: "I gave up going to the pub because I just hated the stink on my clothes ... but this changes everything."
The bold move in a country not traditionally known for its healthy lifestyle will be closely monitored by other European governments considering similar legislation.
Health Minister Micheal Martin marked the historic day by savouring a smoke-free breakfast in Bewley's Oriental Cafe on Grafton Street - a hub of Dublin social life since the 19th century.
With the rate of heart disease in Ireland the highest in Europe, Martin described the ban as a "no-brainer". "We have to do something extra, go the extra mile, to get that rate down."
Anti-smoking group ASH said smoking killed six times as many people in Ireland each year than road accidents, work accidents, drugs, murder, suicide and AIDS combined.
"Earlier this year I referred to this legislation as the 'health initiative of the century'," said Professor Luke Clancy, chairman of ASH Ireland. "I have no doubt that research will in time justify this statement." Others were not so enthusiastic.
"For me personally, it's a bridge too far," said electrician Shay Mahoney.
"I mean, what's next, compulsory haircuts?" asked Mahoney, who said he has smoked 20 cigarettes a day for the past 20 years but did not think the landlord at his local pub in north Dublin would enforce the legislation.
At Ned's Bar in Dublin, a so-called "early house" which for the past 50 years has been opening at 7:00 am for workers coming off nightshift, manager David Coulahan said he feared for his job if the first morning of the ban was anything to go by.
The impact of the ban will be closely watched across Europe. Norway is set to impose a similar ban in June and European Union health commissioner David Byrne, who is Irish, has said he would like to see the experiment mirrored throughout the bloc.