The main environmental risk with abrasive blasting lies with the abrasive material used and how it is contained.
Despite the name sand blasting, sand is actually seldom used any more, as inhaling the dust has been shown to cause the lung disease silicosis. These days, abrasive blasting uses steel grits, copper slags, walnut shells, powdered coconut and other materials. The most important environmental consideration is choosing an abrasive material that will not contaminate the area and is free from heavy metals.
Garnet – granular crushed stones – is the preferred choice for many abrasive blasters, including Tauranga Sandblasting. With fewer airborne emissions due to its particular crystal structure and being free of the dangerous silicates of sand, garnet avoids the health risks of using sand. With a low chloride content, almost complete absence of silica, a MOHS hardness of 7.5 and a specific gravity of four, garnets are ideal for abrasive blasting.
The crystals are chemically inert, so even if garnet dust finds its way into the natural environment, it adds nothing but bulk – nothing that will affect the ecosystem it enters.
Still, where possible it is best to prevent introducing new elements into the environment, even if just for aesthetic reasons. Where a blasting booth is used, this is fairly easy. The blast material falls to the floor where it can be gathered for reuse or to be disposed of in designated landfills. Garnet can usually be recycled up to five times before the grains become so small as to not be effective for their abrasive purpose in an industrial application.
When abrasive blasting has to be done outdoors, temporary skirts or curtains can contain the spread of particles. A concrete pad or slipway makes it easy to collect the abrasive material. If this is not possible, even just smoothing the ground will help make it easy to scoop up the blast medium. Any remains can be spread and washed down to prevent it being spread by the wind.
Provided the abrasive material is chosen responsibly, the environmental effect of abrasive blasting is relatively minimal.