Quilbie does not ever create an air-tight seal, thus your baby will always have plenty of oxygen to breathe. Some online articles may warn about elevated levels of CO2 from re-breathing, and while this is a serious concern for products that can directly block a child's airways (like crib bumpers), there is no evidence or research to suggest that a baby cover like Quilbie would lead to such extreme CO2 levels that present a hazard, nor have there been any reported incidents or recalls. We also consulted with an independent child safety organization, and they did not express concern for CO2 rebreathing with Quilbie. Most humans are naturally exposed to elevated levels of CO2 such as when indoors or most notably when driving in a car. It is known that being exposed to elevated levels of CO2 for long periods of time can result in fatigue, dizziness, or drowsiness. This is why it can often feel refreshing to roll down your window when driving for extended periods of time. For these reasons, we have added extra breathability holes and a peek-a-boo flap that can be opened to allow fresh air for your baby. We do not recommend using Quilbie for extended periods of time or overnight sleeping. Similar to rolling down your window for fresh air while driving, we recommend checking on your baby every 15 minutes or less by opening up the peek-a-boo flap and allowing fresh air in for your baby.