对环境污染分级有:

问题描述:

对环境污染分级有:
清洁水平
尚清洁水平
轻度污染
中度污染
重度污染
他们分别怎么翻成英语啊 特别是 “尚清洁水平”

Classification of environmental pollution are:
Clean
Still clean
minor/slightly polluted
moderately polluted
Heavily polluted