Air emissions
Airborne emissions have the potential to affect the health, general well being and livelihoods of people and to degrade the environment. Some of Rio Tinto's activities emit sulphur dioxide, fluorides, greenhouse gases and dust.
Given the potential impacts to people and the environment, we need to, and do, understand and control our emissions and their effects, and meet our legal requirements.
Dust results from moving or stockpiling material, traffic movements on unsealed roads, and stack emissions. It is recognised as a general nuisance impacting upon amenity. However, more importantly, dust particles under 10 microns in diameter (PM10) can be retained in the lungs and associated with lung diseases, including asthma and industry specific diseases known as pneumoconiosis. In addition to the particles themselves, dust particulates may contain potentially toxic substances on their surfaces; for example, diesel exhaust fume particles may contain polyaromatic hydrocarbons.
The majority of sulphur dioxide emissions from Rio Tinto's operations come from smelters. Often the metal in the ore is combined with sulphur, which produce oxides of sulphur in the ore smelting process. This can be captured and converted to sulphuric acid for use in refining and other industrial purposes. The efficiency of the capture equipment is variable across the Group and relates to the age and type of the equipment. Small quantities of particulate and gaseous fluoride emissions are mainly inadvertently generated in aluminium smelters when converting alumina to aluminium.
Sulphur dioxide and fluoride emissions have been associated with impacts on human health. Sulphur dioxide has been associated with asthma as well as acid rain in the northern hemisphere, whilst fluoride can be taken up by plants and enter the food chain and can affect the strength of teeth and bones. Rio Tinto aims to have controls in place to minimise any potential health and environmental impacts.
Investigations in 2005 into NOx emissions indicated that there are an insignificant number of operations that may contribute NOx emissions to airsheds to cause significant air quality impacts.
Greenhouse gases are produced through the combustion of fossil fuels, the clearing of land and in some industrial proccesses, and are implicated in climate change. 90 per cent of Rio Tinto's emissions are carbon dioxide. Smaller amounts of methane perfluorocarbons, and other gases are also emitted.
Many of Rio Tinto's operations report emissions information publicly under community 'right to know' emissions programmes such as the Toxic Release Inventory in the US, the National Pollutant Inventory in Australia and the National Pollutant Release Inventory in Canada.
Rio Tinto monitors health in the workplace and has also developed Group-wide occupational health standards, which cover topics such as workplace monitoring of particulate gas and/or vapour exposures. More details.
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