Remove the plastic wrapping carefully from the mattress with a knife or scissors.
Find a room or area where air circulates freely. Choose a spare room with a window that can be left open or use a garage or basement that is not so damp as to encourage mildew in your new mattress.
Lean your new mattress up against a wall. Setting it against a wall will allow air to reach its surfaces, giving the odors a chance to be released.
Rotate the mattress regularly. Whether you decide to air out the mattress for a day, several days, or even weeks, be sure to keep turning it so that every surface will be exposed to air.
Perform a smell test. You will know your mattress is ready for use when you no longer detect the offending odor. How long this takes depends on manufacturer materials and your sensitivity to the smell.