A clinical research study published on Pediatric Pulmonology 46:193–198 (2011)
comparing the Numu mattress (referred to as the Airnetress, the Numu USA commercial name) to other regular breathing mattresses, finding that:

"In summary, we re-introduced here an infant sleeping
surface which is made of permeable netting thus allowing
free air movement through it. The special characteristics
of aeration, ventilation, and resistive properties, aimed to
decrease the likelihood of significant CO2rebreathing,
may decrease important risk factors for SIDS especially in
high-risk populations. "

click here for the research