2. Building many factories that release smoke​

Answer:

Smog from factories represents an existential threat to both the environment and human health. Over the years, different governments around the world have mandated actions to reduce the level of toxic emissions from industrial processes, such as reducing the amount of harmful chemicals used in these processes, and utilizing technologies to capture them before the chemicals enter Earth's atmosphere. In the United States, the Environmental Protection Agency can mandate rules for chemical emissions from the country's numerous factories, though other countries have varying degrees of regulation on these emissions.

Explanation:

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