Individuals flouting the law face a fixed penalty of £50 or a maximum fine on conviction of £1,000. Businesses which fail to stop smoking on their premises could be hit with a £2,500 fine and failure to display no smoking signs could lead to a fine of £200.
Environmental health officers will be on the ground across all the country to ensure that the smoking ban is adhered to and a telephone line has been set up for members of the public to report any breaches of it.
Secondhand smoke, which can contain about 4,000 chemicals, is estimated to contribute to the deaths of 278 lives each year in Northern Ireland.
Health minister Paul Goggins said: "It is internationally accepted that there can be no safe level of exposure to secondhand smoke.
"People do not want to breathe in other people's smoke. That was made very clear at the consultation stage of this legislation. By reducing our level of exposure, this legislation will improve health and save lives."
The ban follows similar legislation in the Republic of Ireland (RoI), Scotland and Wales; research conducted in Ireland and Scotland – which introduced bans in 2004 and 2006 respectively – has found positive health benefits after public places went smokefree.
In the RoI there has been an 83 per cent reduction in air pollution in Irish pubs and an 80 per cent decrease in airborne carcinogens for both patrons and staff.
Health charities supporting the smoking ban in Northern Ireland include the Health Promotion Agency, Ulster Cancer Foundation, the British Medical Association and the Institute of Public Health.
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