In the bed or crib

the mattress is tight against all four sides of the crib so that the child will not fall into a space and become trapped
the mattress is firm and not worn out
the crib frame meets safety standards

there are no pillows or fluffy bedding that could obstruct the child's mouth and nose

To avoid suffocation, check that:

blind and curtain cords are out of reach.
cords or drawstrings on children's clothing are tucked in when playing outside. In winter, use mitten clips instead of mitten cords and neck warmers instead of scarves.
pacifiers are not attached to clothing with long cords.

Children can also suffocate when plastic bags cover their faces, so keep these out of reach.