The contents of volatile org. and inorg. compds. in untreated air from an animal waste utilization plant, as well as after 3 years of biofiltration through a mixt. of compost soil, peat and coconut fiber or oak bark-contg. beds were detd. by chromatog. in accordance with relevant stds. to det. air deodorization efficiency. The filtration efficiency of volatile org. and inorg. compds. decreased from 8/.2% to 55.3% and from 83.3% to 8.3%, resp. After 3 years biofiltration materials should be regenerated by bioaugmentation and biostimulation or replaced by new ones.