In the steel industry, continuous particulate matter (PM) concentration instruments have been used for providing qualitative information on the operation and maintenance of filter bags, but not so much for the quantitative estimation of emissions. In order to evaluate PM emissions in the steel melting shop, the flow rate of the emission gas must be measured continuously because of the widely varying conditions occurring in the exhaust duct. However, public data is not available for continuous gas velocity monitoring in these conditions. In this study different continuous emission monitoring systems for PM were compared in field conditions at a steel melting shop. The objective of this demonstration was to evaluate the applicability of continuous PM emission monitoring systems for quantitative evaluation of emissions. The data collected from the instruments were compared with the results of a manual standard method measured at the same time. Results of the tests showed that the compared instruments were not suitable for the quantitative estimation of dust emissions in widely varying field conditions in the steel melting shop. Another problem concerning the use of these monitors in quantitative measurement of emissions is the calibration of continuous PM concentration monitors. PM concentrations below 2 mg/m(3)(n), which predominate in the steel melting shop for most of the time, cannot be measured very reliably even by using the manual standard method [1].