Pollution can be defined as an undesirable change in the physical，chemical，or biological characteristics of the air，water，or land that can harmfully affect the health，survival，or activities of humans or other living organisms.

污染可以被定义为有害影响健康，生存，活动的人或其它生物体的空气，水，或土地的物理，化学或生物特性的不应该有的变化。