The Portland Aluminium smelter is situated on 600 hectares of land, 500 of which form “Smelter in the Park”, a once-barren area that has been revegetated with a large variety of indigenous plants. This area forms a buffer zone, that protects surrounding residents from the full impact of gaseous emissions from the smelter. There are five monitoring stations at different locations around the smelter that provide data on fluoride and sulfur emissions on a regular basis. Portland Aluminium also routinely test their workers, using urine and blood tests, as well as exposure badges, which monitor the levels of fluoride that staff have been subjected to.
Environmental scientists also do water testing and take tail-bone samples of the local kangaroos and teeth, bone and horn samples of the beef cattle , to test for long-term fluoride exposure. An international botanist expert visits annually to check for signs that toxic emissions may be affecting local vegetation. Signs of fluoride exposure include yellowing and curling of leaves and tissue death.
Portland Aluminium use several methods to prevent excessive fluoride emissions, including the A398 fluoride recovery system, in which fluoride emissions are captured from the hooded aluminium pots and forced through a conveyor of alumina, to form reacted or fluoride-enriched alumina. This is then added to the pots, which reduces the temperature (and therefor the energy required) to obtain the pure aluminium. The particulate and gaseous emissions are filtered through huge canvas bags, also coated with alumina, which traps 98% of fluoride.
In the potrooms, the major point source of fluoride emissions, Portland Aluminium have laser air monitoring of gaseous fluoride, with a traffic light system – green, amber and red. Between 045ppb and 600ppb, the lights are green; between 600ppb and 800ppb the lights are amber and above 800ppb the lights are red, which indicates an error in the process – too many hoods open at the same time.
The Victorian governmetn has produced this site, “Fluoride in the air environment“, which describes the sources of fluoride in Victoria and how it is monitored, including EPA limits.