Atmospheric pollution, arising from sources such as motor vehicles, aircraft, and power generation and other industrial plants, is of increasing concern throughout the world. As a result, new and progressively more stringent legislation is being introduced to control its impact on the environment. Successful implementation of such legislation requires instruments that measure pollution levels accurately. This accuracy is most readily realised by making measurements which are traceable to recognised national or international measurement or calibration standards. Such standards are the subject of this Report.
Examples include measurements of:
- exhaust emissions from automobile and aircraft engines;
- emissions from chemical and combustion processes;
- air quality in rural and urban areas and work place atmospheres;
- natural gas for determination of calorific value and relative density.
This Report provides a short description of the National Physical Laboratory's Primary Gas Standards Facility, discusses the methods used to prepare and certify secondary gas standards in a manner which is traceable to Primary Standards, gives the uncertainties assigned to the concentration values of these secondary standards, where this is required. The Report covers gas standards with concentration ranges of greater than 1ppm. Other techniques may be used for standards which have concentrations lower than this.