Assumptions

•There are no huge alterations or violations for countries who have signed the Montreal Protocol and other related conventions for the protection of the ozone layer over the next 50 years.

•There are no occurrence for extreme external effects(especially for space)or natural disasters which deeply affect the Earth's atmospheric environment over the next 50 years.

•All collected data of ozone from observation stations and satellites are supposed to be reliable.

•According to the agreements made by human being for environmental protection,all attitudes of people exploiting environment and producing towards positive and friendly.