BACKGROUND Prone sleeping position, use of soft mattresses and head covering by bedclothes are known risk factors for sudden infant death syndrome (SIDS). Rebreathing carbon dioxide (CO(2) ) may be a possible mechanism or a confounding factor of SIDS. OBJECTIVE To compare the aeration properties of a new concept of infant sleeping surface (Net) to three commercial mattresses advertised to improve aeration and to two standard infant mattresses. DESIGN Two experiments were performed: (I) A container (head box), filled with 7% CO(2) mixture, was opened to the mattress to allow gas mixture to passively diffuse outside and equilibrate with the surrounding room air. (II) Simulation of normal breathing of an infant, using a unidirectional reciprocal syringe, to determine CO(2) accumulation within the head box. METHODS CO(2) concentrations in the head box were continuously measured until CO(2) levels fell below 1% or for 5 min (experiment I), or until CO(2) accumulation levels plateaued or for 6 min (experiment II). RESULTS The Net had a significantly faster rate of CO(2) elimination (88.5 ± 4.6 and 91.9 ± 0.9 sec, Net alone and when covered with a sheet, respectively) compared to 238.3 ± 14.2 sec to 387.8 ± 7.9 sec for the other mattresses (P < 0.001). Only the Net was able to prevent CO(2) accumulation with maximal CO(2) levels (0.56 ± 0.03% and 1.16 ± 0.05%; Net alone and when covered with a sheet, respectively) significantly lower than the range of 4.6-6.3% for the other mattresses (P < 0.001). CONCLUSIONS The new sleeping surface exhibited significantly better aeration properties in dispersing CO(2) and in preventing its accumulation.