5 Little Monkeys foams are exceptional quality and off gassing is typically non-existent. Occasionally, there could be a faint fresh foam smell that will dissipate quickly and is from the foams being vacuum packed. If you find there is the fresh foam smell when you first open your mattress, we recommend waiting anywhere from 2-24 hours before putting on your 5 Little Monkeys Mattress Protector and making up your bed.