What wind direction has the most impact?
High lead-in-air results in Port Pirie are strongly influenced by north-west to north-east winds.
The strong north/north-west winds blow across the smelter, picking up emissions and lead dust on the way, then deposit them predominantly in the south and south-east areas of the city. This is where the highest proportion of children with elevated blood lead levels live.
The strongest north/north-west winds are most prevalent in winter, so higher lead-in-air results are experienced then. There is also a big difference in wind direction and wind speed during the day and at night.