Zone ( o3 ) is a light blue gas with smell if fresh grass in normal temperature . a thin layer if ozone exists in upper aterosphere above 20 - 30kms from the ground . it can absorb harmful rays in the sunlight and protect the earth creature from being injured 臭氧俗称活氧,在常温下是一种具有草鲜味的淡蓝色气体,在距离地面20 - 30公里高空,中分布薄薄的臭氧层,吸收阳光中有害光线,保护地球上生物的生命安全,科学家们对臭氧进行了大量研究。