Otago Regional Council air quality scientist Deborah Mills said this could mean people were better prepared for the colder temperatures this year and were burning dry wood.
As of January 1, burning coal was prohibited in Alexandra, Clyde, Cromwell and Arrowtown.
When the first cold snap occurred after the mild autumn, the only town to exceed the national environmental standard (NES) limit of 50 micrograms per cubic metre was Cromwell, she said.
This month, conditions which normally brought high air pollution - sunny skies, calm conditions and temperatures below zero - did not result in high levels.
Alexandra experienced such conditions for five consecutive days early in the month, as temperatures dropped to -3degC on some mornings.
In more recent days, Alexandra had clocked up three readings higher than 50mcg per cu m and Arrowtown and Milton one each.
Cromwell, which had exceeded the standard eight times, the most of any town in the region, had recorded hourly rates of 200mcg per cu m, but a 24-hour high of only 68mcg per cu m.
A more detailed look at the figures also showed the high levels were not lasting as long in the evenings as they had in the past.
