Cause Altitude sickness is caused by the lower amount of oxygen in the air at higher altitudes.
Many people travel to mountainous areas to hike or ski.
The likelihood of symptoms increases as the altitude gets higher. First aid for severe symptoms Quickly take your child to a lower altitude. Descend at least 2000 feet, and always go below 10,000 feet elevation. If your child cannot walk, carry him or her in a sitting position. Give the child oxygen as soon as it becomes available.