sewage gas

例句：

1. 1.The factory produces a lot of sewage gas during the day.
   这家工厂在白天产生大量的污水气体。
2. 2. The sewage gas is dangerous and must be treated before it can be released into the air.
   污水气体是危险的，必须经过处理才能排放到空气中。
3. 3.The plant's emissions are monitored to ensure they do not exceed safety limits.
   该工厂的排放被监测以确保它们不超过安全限值。