When certain gases mix with water in the atmosphere, They become acid rain. This can kill forests hundreds of miles away from the factories that make the gases. Then nothing can grow in the soil.
Apart from acid rain the earth is also polluted by the chemicals that come from some old factories. Lead is one of the very dangerous metals that often gets into the soil and into the vegetables we eat. When these vegetables are eaten,the lead in them stays in the body and is particularly dangerous for children