Here's why:

* Pollution: Environmental science studies the sources, effects, and control of pollutants in the environment.

* Recycling: Environmental science explores the processes of waste management, resource recovery, and sustainable practices like recycling.

While pollution and recycling might have aspects related to other fields like:

* Chemistry: Understanding the chemical composition of pollutants and how they interact with the environment.

* Biology: Studying the impact of pollution on living organisms.

* Engineering: Developing technologies for waste management and pollution control.

Environmental science acts as the umbrella discipline encompassing these various fields to address the broader environmental challenges related to pollution and waste management.