There isn't one single word that perfectly describes a substance that makes the air, water, or soil dirty. It depends on the context and what specifically you're referring to. Here are some options:

General terms:

* Pollutant: This is a broad term that encompasses any substance that contaminates the environment, including air, water, and soil.

* Contaminant: Similar to pollutant, this term refers to any substance that makes something impure or unfit for use.

* Polluter: This term refers to the source of the pollution, such as a factory or a vehicle.

More specific terms:

* Air pollutant: This refers to substances that contaminate the air, such as smoke, gases, and particulate matter.

* Water pollutant: This refers to substances that contaminate water, such as sewage, chemicals, and oil spills.

* Soil contaminant: This refers to substances that contaminate soil, such as pesticides, heavy metals, and industrial waste.

Other terms:

* Toxic substance: This refers to a substance that is poisonous or harmful to living organisms.

* Hazardous waste: This refers to waste that is dangerous to human health or the environment.

The best term to use depends on the specific situation and what you want to emphasize.