An extractor system comprising: - a base unit; - a positive pressure conduit configured to convey the positive pressure gas stream towards a work area; - a negative pressure conduit configured to convey the negative pressure gas stream from the work area; wherein the positive pressure conduit is concentric with the negative pressure conduit; - a filter for filtering air returning from the work area or directed to the work area; and - a hood coupled to receive the positive pressure gas stream and to direct the positive pressure gas stream into a region around the work area and to draw airborne components from the work area into the negative pressure gas stream, the hood comprising an outer shroud which is essentially a rounded bell and an inner shroud positioned within the outer shroud, wherein a sidewall of the outer shroud is spaced from the a sidewall of the inner shroud with an annular region between the sidewalls (44,46) of the outer and inner shrouds, the positive pressure gas stream flowing through the annular region, wherein the inner shroud sidewall terminates in a lower peripheral flange extending beyond the outer shroud for directing the positive pressure gas stream, an upper surface of the flange being spaced from a lower perpheral edge of the outer shroud to define an annular opening or gap (82, 94); the base unit comprising a blower driven by a motor which is controlled by control circuitry, the blower being connected between the negative pressure conduit and the positive pressure conduit drawing air into the hood and redirecting it again from the negative pressure conduit into the positive pressure conduit, wherein the filter is arranged between the negative pressure conduit and the positive pressure conduit upstream or downstream of the blower, wherein the air returning from the hood in the negative pressure conduit is directed through the filter before being reintroduced into the blower, the system further comprising a suction air adjustment directing air into the blower and a return air adjustment for adjusting the flow rate of returning air, wherein a ratio of the cross-sectional area of the positive pressure conduit and the negative pressure conduit is between approximately 4:1 and 0.7:1; the extractor system being configured such that a ratio of flow rates of positive pressure gas stream and the negative pressure gas stream is between approximately 1:1 and 0.5:1; and wherein the ratio of the flow rates of the positive pressure gas stream and the negative pressure gas stream is manually adjustable by a user by adjusting an air gap (82, 94) between a movable section of the outer shroud and the flange. - a base unit; - a positive pressure conduit configured to convey the positive pressure gas stream towards a work area; - a negative pressure conduit configured to convey the negative pressure gas stream from the work area; - a filter for filtering air returning from the work area or directed to the work area; and - a hood coupled to receive the positive pressure gas stream and to direct the positive pressure gas stream into a region around the work area and to draw airborne components from the work area into the negative pressure gas stream, the hood comprising an outer shroud which is essentially a rounded bell and an inner shroud positioned within the outer shroud, wherein a sidewall of the outer shroud is spaced from the a sidewall of the inner shroud with an annular region between the sidewalls (44,46) of the outer and inner shrouds, the positive pressure gas stream flowing through the annular region, wherein the inner shroud sidewall terminates in a lower peripheral flange extending beyond the outer shroud for directing the positive pressure gas stream, an upper surface of the flange being spaced from a lower perpheral edge of the outer shroud to define an annular opening or gap (82, 94); the base unit comprising a blower driven by a motor which is controlled by control circuitry, the blower being connected between the negative pressure conduit and the positive pressure conduit drawing air into the hood and redirecting it again from the negative pressure conduit into the positive pressure conduit, wherein the filter is arranged between the negative pressure conduit and the positive pressure conduit upstream or downstream of the blower, wherein the air returning from the hood in the negative pressure conduit is directed through the filter before being reintroduced into the blower, the system further comprising a suction air adjustment directing air into the blower and a return air adjustment for adjusting the flow rate of returning air, wherein a ratio of the cross-sectional area of the positive pressure conduit and the negative pressure conduit is between approximately 4:1 and 0.7:1; the extractor system being configured such that a ratio of flow rates of positive pressure gas stream and the negative pressure gas stream is between approximately 1:1 and 0.5:1; and wherein the ratio of the flow rates of the positive pressure gas stream and the negative pressure gas stream is manually adjustable by a user by adjusting an air gap (82, 94) between a movable section of the outer shroud and the flange.