Cooktop comprising a plurality of burners, and - at least a fan seated so as to draw air from the environment and which must be made operational at least when the overlying horizontal hood is in operation, - suitable air ducts leading at least part of said air from the outlet of said at least one fan to the outside of the same cooktop through at least some of a range of ventilation openings wherein - said burners are blown burners - said fan is the same fan that feeds with air said blown burners and wherein said ventilation openings - are shaped so as to direct upwards, in the direction of a horizontal hood overlying the same cooktop, the air jets exiting therefrom; - are sufficiently close to each other to ensure that said air jets they produce may form substantially a continuous curtain of ascending air which, in a plan view, circumscribes, at least partially, at least all the burners operational at the moment, such curtain forming an air blade sufficient to constitute an obstacle to the lateral deviation of fumes and vapours produced by the operating gas cookers and a guide thereof, instead, towards the said hood, - where, in particular, said curtain may be composed of multiple portions also discontinuous and each surrounding a single one of said more burners; - are suitably dimensioned and calibrated based on the predetermined head of the fan so that the air jets have a speed comprised between a minimum value sufficient to ensure a curtain of sufficient stability and persistence against disturbances and a maximum value compatible with the formation of the said flow. - at least a fan seated so as to draw air from the environment and which must be made operational at least when the overlying horizontal hood is in operation, - suitable air ducts leading at least part of said air from the outlet of said at least one fan to the outside of the same cooktop through at least some of a range of ventilation openings wherein - said burners are blown burners - said fan is the same fan that feeds with air said blown burners and wherein said ventilation openings - are shaped so as to direct upwards, in the direction of a horizontal hood overlying the same cooktop, the air jets exiting therefrom; - are sufficiently close to each other to ensure that said air jets they produce may form substantially a continuous curtain of ascending air which, in a plan view, circumscribes, at least partially, at least all the burners operational at the moment, such curtain forming an air blade sufficient to constitute an obstacle to the lateral deviation of fumes and vapours produced by the operating gas cookers and a guide thereof, instead, towards the said hood, - where, in particular, said curtain may be composed of multiple portions also discontinuous and each surrounding a single one of said more burners; - where, in particular, said curtain may be composed of multiple portions also discontinuous and each surrounding a single one of said more burners; - are suitably dimensioned and calibrated based on the predetermined head of the fan so that the air jets have a speed comprised between a minimum value sufficient to ensure a curtain of sufficient stability and persistence against disturbances and a maximum value compatible with the formation of the said flow.