A mineral wool fibre mat curing oven for curing a continuous mat of mineral wool fibres mixed with binder to form a continuous cured mineral fibre mat, wherein the curing oven comprises: an entrance end; an exit end; at least one heating zone (3a-3g) between the entrance end and the exit end; a conveyor for conveying a continuous fibre mat from the entrance end through the heating zone(s) (3a-3g) to the exit end; and an air circulation system for heating a fibre mat by blowing or drawing heated air through the fibre mat as is progresses through the heating zone(s) and maintaining a flow of gas through the curing oven, the air circulation system comprising one or more element(s) selected from the group consisting of: (i) a heat source; (ii) a combustion fan arranged to blow ambient air over the heat source and into the heating zone; (iii) a circulation fan arranged to direct heated air through the fibre mat and (iv) an extractor fan arranged to extract exhaust air, the air circulation system being configured to ensure adequate ventilation through the oven under normal operation; characterised in that the oven further comprises: an air injecting system configured to inject ambient air into at least one heating zone in circumstances in which there is a risk of inadequate ventilation, notably in the event of: a failure of one or more of: the main power supply, at least one exhaust fan, at least one circulation fan in at least one heating zone, at least one combustion air fan; an emergency stop; an interruption in the conveyor transport. an entrance end; an exit end; at least one heating zone (3a-3g) between the entrance end and the exit end; a conveyor for conveying a continuous fibre mat from the entrance end through the heating zone(s) (3a-3g) to the exit end; and an air circulation system for heating a fibre mat by blowing or drawing heated air through the fibre mat as is progresses through the heating zone(s) and maintaining a flow of gas through the curing oven, the air circulation system comprising one or more element(s) selected from the group consisting of: (i) a heat source; (ii) a combustion fan arranged to blow ambient air over the heat source and into the heating zone; (iii) a circulation fan arranged to direct heated air through the fibre mat and (iv) an extractor fan arranged to extract exhaust air, the air circulation system being configured to ensure adequate ventilation through the oven under normal operation; characterised in that the oven further comprises: an air injecting system configured to inject ambient air into at least one heating zone in circumstances in which there is a risk of inadequate ventilation, notably in the event of: a failure of one or more of: the main power supply, at least one exhaust fan, at least one circulation fan in at least one heating zone, at least one combustion air fan; an emergency stop; an interruption in the conveyor transport. an air injecting system configured to inject ambient air into at least one heating zone in circumstances in which there is a risk of inadequate ventilation, notably in the event of: a failure of one or more of: the main power supply, at least one exhaust fan, at least one circulation fan in at least one heating zone, at least one combustion air fan; an emergency stop; an interruption in the conveyor transport.