The just released Ministry for the Environment report looked at air quality breaches around New Zealand ahead of new standards coming into force next year.
Otago was split into four areas in the report, with a grouping of seven Central Otago towns - including Alexandra, Ranfurly and Cromwell - recording by far the highest number of air quality breaches.
It had the most high pollution nights in all but one of the years from 2006 to 2012, with breaches ranging from 50 to 91 per year.
In all years, the area significantly exceeded the new standard, which will require councils to reduce high pollution nights to three or fewer per year next year and one per year by 2020.
Another of the Otago areas, which includes Green Island, Milton, Mosgiel, South Dunedin and Palmerston, also had some of the filthiest air quality in New Zealand, coming in the top four in four of the seven years included in the report.
Otago Regional Council chairman Stephen Woodhead said while it would be preferable not to be on top of the list, the climate and geography, particularly of some of Central Otago towns, presented ''unique'' challenges.
''As a result of the climate and geography, [the towns] suffer from these inversion layers,'' Mr Woodhead said.
This problem was not just confined to Otago, with other South Island locations also affected, but to a lesser extent.
The pollution was largely from household fires and was made worse when people burned wet wood.
The council was determined to improve the situation, but there was no way it would be able to meet the new guidelines by next year.
''When you are dealing with human behaviour ... it takes time.''
Improving the situation was important, as worse air quality was connected to higher numbers of hospital admissions of people with respiratory problems.
Not meeting the guidelines would also make it harder for businesses which produced emissions to gain resource consent.
The council will look at its strategy on the issue as part of developing its long term plan.
