The relationship between plants, animals

The relationship between plants, animals, people, and the environment, or the study of this
ecology

Harmful chemicals and waste, and the damage they cause to the environment
pollution

Unhealthy air in cities that is a mixture of smoke, gases, chemicals etc
smog

A place where garbage is buried underground
landfill

Things such as old food, empty bottles etc that you do not need any more and that you throw away
rubbish

To make the amount or size of something less than it was before
reduce

Something bad or difficult that you have to deal with
problem

Synonyms of the word “rubbish”
garbage trash
litter waste

We must also ______ paper, glass and other materials that people can use again.
recycle