Legal regulations as well as technoL and ecol. conditions and construction and operational solns. for exhaust gas purifn. were reviewed. The parameters of a long-term operation of a water boiler with a bag filter under low load were analyzed. The rate of consumption of filter bags was detd. at varying compn. and temp. The most unfavorable conditions of the filter working were obsd. during flue gas temp. drops and at periodic shutdowns of the bag filter.