Pollution in a dream stands for something toxic creeping into your surroundings or thoughts. Tradition reads it as a sense that an environment, habit or relationship has become unhealthy to breathe in.
Does the traditional reading fit your dream, or did it mean something else to you?
My Cosmic Code has a private dream journal. Write a dream down and the app picks out the symbols in it, shows what dream books say about them and, over time, which words recur across your entries. The journal is stored on your device only.