Public Health are writing to proprietors and licensees responsible for pubs, restaurants, cafés, hotels and clubs advising them of their duty under the new law.
They will have to display notices inside their premises and at any entrances used by the public making it clear smoking is not permitted by law there.
Senior public health specialist Steve Harvey, who has worked on the new law, said the onus will be on the proprietor or licensee to ensure the public and their employees comply with the law.
