The main objective of the Calibration Laboratory of Immission (KLI) is to calibrate measuring instruments and calibration sources for air pollution measurement. Our laboratory is accredited for calibration of SO2 and NO-NOx in range up to 500 nmol/mol, CO up to 20 umol/mol, O3 up to 1000 nmol/mol and BTX up to 12 nmol/mol. Identification number of the KLI is 2284, so it is easy to find details on the Czech Accreditation Institute web pages (www.cai.cz).

The fundament of calibration methods of KLI is to provide traceability of working etalons used for calibrations according to the Metrology Law, so that etalon?s accuracy could pass in interlaboratory comparison tests. KLI provides high accuracy and stability by using primary reference standards from the reputable producers - Dutch Nederlands Meerinstituut (NMi) for SO2, NO and O3 and British National Physical Laboratory (NPL) for BTX. These certified materials are produced using gravimetric method (gases are weighed), so they are traceable to the basic SI unit - mass. Other nitrogen oxides (NOx) concentrations are traceable by NO concentration after reduction in molybdenum convertors. Convertor?s high efficiency is proved by titration of NO-air mixture by ozone. The main technique for working etalons traceability is dilution of primary reference standards (high concentration) using static pressure injection method. We use ultra-precision pressure gauges and vessels to comply with all mentioned above.

The KLI use Standard Reference Photometer No. 17 from the National Institute of Standards and Technology as a primary calibration source of ozone for traceability of tropospheric ozone analysers. This O3 etalon was the fourth in the whole Europe and we have used it since 1994 so we have a long experience with it.

Our laboratory can successfully analyse significantly higher concentrations of the mentioned gaseous compounds beyond the scope of accreditation. We calibrated NO sources of European producers for medical purposes for instance. NO levels were 1000 times higher than the calibration range, they reached the emission concentration level. Regarding to the gas dilution technology we use flow metering techniques in range 5-10000 ml/min and pressure gauges up to 21 MPa, which is necessary for calibration over accredited range.

The Calibration Laboratory of Immission takes part in international interlaboratory comparison tests since 1992 arranged by top laboratories, e.g. Umweltbundesamt UBA (Federal Environment Agency) in Langen and Essen (Germany), the research centre of the European Union - Joint Research Centre - European Commission (JRC-EC) in Ispra (Italy) and the International Bureau for Weights and Measures - Bureau International des Poids et Mesures (BIPM) in S?vres (France). The Calibration Laboratory of Immission of the Czech Hydrometeorological Institute won recognition at all-European level for its results in these interlaboratory comparison tests.