(Air pollution) can be from (vehicle emissions).Logical formLearned from6 sentences. Effects may pertain-to an (air pollution).Logical formLearned from6 sentences. Regard can be to (air pollution).Logical formLearned from6 sentences. Pollution can be from fires.Logical formLearned from6 sentences. (Pollution sources) may be identified.Logical formLearned from6 sentences. Changes can be in (air pollution levels).Logical formLearned from6 sentences. A (pollution control) can be improved.Logical formLearned from6 sentences. Pollution can be from nitrogen.Logical formLearned from6 sentences. Pollution can be from (animal waste).Logical formLearned from6 sentences. Regulations may govern pollution.Logical formLearned from6 sentences. A natural environment may undergo pollution.Logical formLearned from6 sentences. Pollution may cause problems.Logical formLearned from6 sentences. Exposure can be to outdoor (air pollution).Logical formLearned from6 sentences. An (air pollution situation) can be worse.Logical formLearned from6 sentences. Episodes can be constituted-of-or-filled-with pollution.Logical formLearned from6 sentences.