POLLUTION!!

Pollution is the addition to the ecosystem of something which has a detrimental effect on it. One of the most important causes of pollution is the high rate of energy usage by modern, growing populations. 

Different kinds of pollutions:

Noise pollution: Sounds are carried by the air causing irritating effects on humans and other animals.
Tobacco Smoke: It's not only the smoker who is affected, everyone who inhales it the air can be affected too. There is a special connection between tobacco smoke and lung cancer.
 Lighting pollution: There is a lot of light in cities so it causes Lighting pollution