An equivalent may pertain-to pollution.Logical formLearned from4 sentences. A (pollution level) can be low.Logical formLearned from4 sentences. Shippers may pay for pollution.Logical formLearned from4 sentences. A (water pollution problem) can be serious.Logical formLearned from4 sentences. Pollution can be from (hog farms).Logical formLearned from4 sentences. A country may reduce pollution.Logical formLearned from4 sentences. (Air pollution regulations) may pertain-to a state.Logical formLearned from4 sentences. Pollution can be from farms.Logical formLearned from4 sentences. Pollution may pose a threat.Logical formLearned from4 sentences. Controversies can be over pollution.Logical formLearned from4 sentences. Pollution may be left by (mining operations).Logical formLearned from4 sentences. Pollution can be from (truck traffic).Logical formLearned from4 sentences. (Air pollution controls) may pertain-to a state.Logical formLearned from4 sentences. (Power plants) can be a generator of (sulfur dioxide pollution).Logical formLearned from4 sentences. Public health may be affected by pollution.Logical formLearned from4 sentences.