One of the most frequent complaints from communities surrounding the bauxite mining and alumina processing plants is dust. The dust in the air can be measured and compared with the air quality standards that define the acceptable limits to protect health. The instruments measure particulate matter, which is the term, used for a mixture of solid particles and liquid droplets in the air. The ambient air quality standards for particulate matter are:
- Total suspended particulates (TSP) which is a measurement of the amount of particles in the air with diameter less than or equal to 100 microns and
- PM10 which measures particles with diameter less than or equal to 10 microns (i.e. respirable portion).
Both of these standards have short-term and long-term values referred to as 24-hour maximum and the annual average.
Ambient concentrations of atmospheric gaseous emissions from the stacks at the alumina plants are monitored on a regular basis. These include sulphur dioxide, nitrogen oxides, ozone and carbon monoxide. Ambient levels of these gases are determined by continuous samplers, which are placed within communities surrounding the respective alumina plants. These samplers are placed in areas found within the predominant wind direction as well as the opposite upwind direction. To date, the respective NRCA standards for these gases have not been exceeded.
The National Ambient Air Quality Standards (1996) and Regulations (2006) indicates the standards being observed for air quality in
Within the bauxite/alumina industry the major concern for water quality is the potential for sodium contamination of surface and ground water resources through sodium migration to the aquifer from mud disposal areas or spillages and effluent/waste water disposal to surface water bodies. As a result, sodium concentration is closely monitored at various points around all the alumina facilities. However, water quality monitoring is not only restricted to sodium, but also includes pH, hardness, alkalinity, sulphate, nitrate, conductivity, chloride and total dissolved solids. Around each alumina facility several monitoring points including domestic water and monitor wells are sampled monthly and surface water bodies are analyzed weekly in some cases. The Water Resources Authority (WRA) has been instrumental in the establishment of the individual monitoring programmes. Data collected is submitted to both the JBI and the WRA for review and independent monitoring is conducted by the government agencies, as a verification check on information submitted. In addition to routine water quality monitoring, special hydro-geological studies were done to define the extent of any sodium contamination of ground water resources. It must be pointed out that domestic water supply is not affected by bauxite and alumina operations.