They keep our air clean, reduce noise pollution, improve water quality and provide food and building materials.
他们保持我们的空气清洁，减少噪音污染，改善水质，提供食品和建筑材料。
2
In China, the government is trying to solve not only air and water pollution problems but also noise pollution problems.
在中国，政府不仅试图解决空气和水污染问题，还试图解决噪音污染问题。
3
Examples range from contamination of the food or water supply, to high levels of air or noise pollution, a chemical accident, a disease outbreak or a natural disaster.