Interest in biofiltration as an air pollution control is growing, but literature about this technology often is not specific about the applications or gas streams that it can effectively treat. Realize that most regulatory authorities are not yet well educated in biofiltration technology as a form of quality air pollution control. This is due mainly to the lack of operating information. This deficiency will change as more commercial applications evolve and as projects state longer operating data. Some of the existing designs and failures have created doubts for the environmental regulators. Therefore, if considering a biofilter, expect more stringent regulations from construction and demonstration of the system's air pollution control capabilities and program compliance.