Large congenital nevi form in the womb very early in development, within the first twelve weeks of pregnancy. They are caused by a defect during embryologic development. There is no known method of prevention. They appear in either sex, in all races, and on any areas of the skin.
I recommend that you have a carbon monoxide detector within 15 feet of each bedroom door, 10 feet is even better if you can afford more detectors. If two bedroom doors are 30 feet apart or less, then place one in the middle. If however they are more than 30 feet apart you will need more than one detector.
Types of carbon monoxide detectors. A carbon monoxide detector is your only line of protection against the many potential sources of carbon monoxide in your home or at work. Detectors are also refered to as alarms, monitors, meters, and testers. Conventional carbon monoxide detectors are designed to prevent acute carbon monoxide poisoning.