Section 8 (a)(ii) of the National Environmental Management: Air Quality Act (2004) requires that national standards be established for municipalities to monitor point, non-point and mobile source emissions. This is brought to effect in the National Framework for Air Quality Management in the Republic of South Africa (2007). Limits for the density/opacity of exhaust emissions from diesel-fuelled vehicles have been prescribed in South African legislation viz. GN R1651 of 20th September 1974, Regulations Concerning the Control of Noxious or Offensive Gases Emitted by Diesel-Driven Vehicles. Emission testing will be undertaken in view of the most applicable legal and best practice standards, set both locally and internationally and include, but not limited to: