Non-polluted Sphagnum fallax moss was transplanted from Augustow region and used as bioindicator for studying the air pollution with Cr, Pb and Zn in the vicinity of Warsaw steel mill in 1993-2008. The moss samples were washed with distd. H(2)O and exposed to atm. air for 12 weeks, mineralized in muffle furnace, dissolved in 30% HCl soln. and analyzed for the heavy metals by at. absorption spectrometry. The max. Cr, Pb and Zn contents in the moss in 1993 were 10.6, 35.9 and 145.0 mg/kg, resp., and decreased down to 4.8, 22.7 and 110.0 mg/kg, resp., in 2008. The steel mill remained, however, a "hot spot" in the Warsaw area.