If pre-existing detrimental activity is present, must the new adjacent landowner remove the resulting harm?

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If the source of harm already exists within a person's property—such as an established tannery or dyeing facility—and another person subsequently cultivates adjacent unowned land (mawat) and builds a house suffering from this pre-existing detriment, the removal of that harm is not required from the original owner. This is because the original owner did not initiate a new harmful act.