Apparatus and a method for removing particulate matter from an enclosure having an internal space and an opening into the internal space. The apparatus includes: a cover positionable over the opening; an inlet conduit that extends through the cover and is adapted to direct gas from a gas source to a gas outlet within the internal space so that particulate matter within the internal space is dislodged. Gas and entrained particulate matter is drawn from the internal space firstly through an outlet conduit and the particular matter is separated. Concentration of particulate matter in gas leaving the enclosed space is sensed and its value displayed to an operator so that operation can continue until a satisfactory value of the concentration is achieved. The gas outlet may be comprised in an elongate lance that is passed through the cover and can be manipulated by a user. The lance may display data.