the invention provides a shroud for use in apparatus incorporating a cyclonic dust separation divice for separating dirt and dust from an airflow , the shroud having a perforated portion having a multiplicity of perforations for allowing the airflow to pass therethrough . according to the invention , the upstream edge of each perforation meets the upstream surface of the shroud at a sharply defined angle . the invention improves the performance of the dust separation apparatus in conjunction with which the shroud is utilized .