Abstract: The invention relates to a ventilation insert for ventilating textiles, shoes and soles of shoes, gloves, protective helmets and their visors, protective goggles, insulating mats, cushioning mats, knee pads and shin pads, headgear and similar articles. The invention proposes a ventilation insert in which an open-pored support layer (1) is provided with an open-pored cover (1.1, 10) or individual covering elements (2) which are at least partly composed of a material (3) which undergoes a swelling or shrinking effect on account of moisture, heat or an electrical voltage, or a material (3) of this type is connected to the support layer (1), the cover (1.1, 10) and/or the covering elements (2) or constitutes the support layer or cover in such a way that ventilation openings (5, 12) in the support layer (1) and/or in the cover (1.1, 10) are exposed or closed on account of the swelling or shrinking effect.