Sleeping in a room with a fan lowers a baby’s risk of sudden infant death syndrome by 72 percent, a new study has found.

The finding, published Monday in The Archives of Pediatrics and Adolescent Medicine, is the latest evidence to suggest that a baby’s sleep environment is a critical factor in the risk of SIDS, which is diagnosed when an infant’s sudden death cannot be explained by other factors.

The study was not designed to identify why fans make a difference, but researchers said they thought that by circulating air, fans lowered the risk of “rebreathing” exhaled carbon dioxide. That risk has been suggested as a reason the rate of SIDS is higher when children sleep on their stomach, in a soft bed or without a pacifier.

Since 1992 the rate of SIDS deaths has dropped by more than half, to about one death per 2,000 live births from 2.4 per 1,000. The decline is linked to a national “Back to Sleep” campaign that promotes putting babies on their back instead of their stomach, which has been shown to lower the risk of sudden death.