Testing carried out by the Otago Regional Council has confirmed that Clyde's air pollution does not contribute to Alexandra's air pollution problem.
Because of their geography, the two towns were more susceptible to the build-up of smoke than most other towns in Otago, regional council environmental information and science director John Threlfall said.
Council scientists had looked at wind direction during high air pollution days last winter and from that information, built a model to predict air and smoke movement.
"The results were that less than 0.1% of the smoke in Alexandra was from Clyde, and a similar figure for the other way round," Dr Threlfall said.
Clyde has recorded four high air pollution days this month, while Alexandra has recorded nine.
Dr Threlfall said that during the council's air plan consultation, many Alexandra residents asked whether Clyde's air pollution was affecting Alexandra's smog levels.
"Clyde and Alexandra have the same geography and the residents of both towns use similar heating appliances and fuel.
"The problem in those towns is that on high pollution days, cold air drains from the hills in the basin and a pond of cold air develops on the floor of the valley.
'That pond separates the Alexandra and Clyde basin floor from higher winds that might disperse the air pollutants," he said.
Smog levels were often the highest between 8am and 9am.
"Everyone gets up in the morning and relights their fires.
"However, what goes up, doesn't disappear. The smoke comes down to nose height and hangs around until the sun breaks it down later in the day and mixes it up so, in effect, you get the same smoke twice," Dr Threlfall said.
