Otago University researchers say the law should be changed so smoking is restricted to just half of any outdoor area attached to a hospitality venue.
The researchers tested the air in designated smoking areas and found it contained an average of 72 micrograms of harmful second-hand smoke particles per cubic metre of air.
This is more than three times the level of smoke particles inside the bars, five times the level in pubs and six times the level in cafes.
In an article published in the New Zealand Medical Journal, the researchers say the concentrations of smoke could affect workers' and patrons' health.
