The present application relates to a process for preparing a surface-reacted calcium carbonate in an aqueous environment. When the calculated value of the concentration of CO2 in the vehicle passenger compartment exceeds a predetermined value, the inside and outside change-over door is changed over to the outside air mode. The skirt is formed with a groove which creates a suction channel between the skirt and the contact surface in the chamber. The adjustable support can be made into a neck supporting pillow, or a cushion adapted to be removably attached to the back of a chair, to support the back of a seated user.