Some waste that is left over from the manufacturing process such as plastic or paint is poisonous. We call poisonous waste hazardous waste. Burning these wastes puts poisons into the air and soil. This is harmful to all living organisms. Other factories empty wastes into rivers, polluting and damaging the ecosystem.
Some landfills contain household and industrial chemicals.
The chemicals pollute the soil and contaminate ground water. As the amount of garbage increases the space for landfill decreases. Many communities refuse new landfills because of the contamination. Some parts of the USA allow garbage to be burned in large incinerators. Air pollution is created by burning.