NOx Emissions
An assessment was completed by URS in early 2005 on the relevance of reporting oxides of nitrogen (NOx) for the Rio Tinto group. This initial assessment looked at the likely significance of NOx for group public reporting based on potential community health or environmental impacts. The study was based on the assumption that the particular group operations were the only emitters of NOx in their regional airshed. The initial assessment concluded that NOx emissions are of significance at a group level due to the risk associated with emissions.
Following the initial assessment, additional work to investigate the significance of NOx emissions at the local airshed level was undertaken. This follow-up study aimed to broaden the knowledge gained from the initial assessment by investigating the significance of NOx emissions based on the NOx contribution that a group operation makes to the airshed in which it operates, and the quality of the airshed based on the impact of all other identified contributions.
This additional work indicated that there are an insignificant number of operations that may contribute NOx emissions to airsheds resulting in significant air quality impacts. That conclusion was due to group operations being either not significant as a proportion of total NOx emissions in an airshed (including other contributors), or where group operations were judged to be significant contributor, the airshed quality did not appear to be significantly impacted by those emissions (as indicated by measured NOx levels being within regulatory limits).
To enable a full and final analysis of the case for group reporting of NOx emissions, an expert air quality consultant was engaged to review the outcomes of the URS study. The expert review concluded that whilst the assessment methodology employed by URS has merit as a screening tool, it did not consider the nature of the NOx emissions in a way that would enable the significance of the source to be determined. The consultant has subsequently been asked to develop a methodology for Rio Tinto to apply for the group reporting of NOx emissions. Work is in progress and a draft report is awaited.
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