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Main Difference – Pollutant vs. Contaminant

Both pollutant and contaminant refer to undesirable or unwanted materials. Pollutant is a substance that pollute the environment while contaminant is a substance that contaminate another substance or an environment. It is important to understand the difference between pollution and contamination in order to understand the difference between pollutant and contaminant. Pollution is the introduction of harmful substance to the environment, and contamination is the presence of an unwanted constituent, or impurity in a material,  physical body, or natural environment. In fact, pollution is contamination that results in or can result in adverse effects. From these two definitions, it becomes clear that pollutant refers to a harmful substance, but contaminant is not necessarily harmful since contamination refers simply to the presence of a substance where it should not be. This means that all pollutants are contaminants, but not all contaminants are pollutants. Therefore, the main difference between pollutant and contaminant is that pollutant is always a harmful substance whereas contaminant is not always harmful.

What is a Pollutant

Pollutant is a substance that causes pollution; it causes adverse effects on a resource or an environment. In simple terms, pollutants refer to the substances that pollute the environment.

When a certain substance is considered as harmful in any given aspect, the substance is considered as a pollutant. Even if it is a substance that is normally present there, when it exceeds harmless limits, the term pollution is used. Pollutants can be categorized according to the sources they are derived from. Soil pollutants, Noise pollutants, Water pollutants, and Air pollutants are some of these categories. There can be various pollutants – substances that pollute the environment – in these categories.

For example, Carbon Monoxide (CO) which is released to the atmosphere through the combustion of fuel in engines and vehicles has many adverse effects health effects. It reduces oxygen delivery to the body’s organs and tissues, and at extremely high levels, it can lead to death. Some other common air pollutants include Nitrogen Dioxide, Lead, Sulfur Dioxide, particulate matter, etc. The severity of a pollutant can be measured by its chemical nature, the concentration, and the persistence.Difference Between Pollutant and Contaminant

What is a Contaminant

As explained above, contamination is the presence of an extraneous material; it is the presence of a substance that is normally not present. The contaminant is a certain substance that exists in a place where it should not be. A contaminant is not necessarily harmful or adverse. For example, adding some water to milk can be considered a form of contamination.

However, when the terms contaminant and contamination are used in relation to subjects like environment, food and medicine they can refer to the addition of harmful substances.. Difference Between Pollutant and Contaminant - image 1

Difference Between Pollutant and Contaminant


Pollutant is a harmful or poisonous substance that pollutes something.

Contaminant is a foreign substance or impurity that contaminates something.

Adverse effects

Pollutants always create harmful effects.

Contaminants do not always create harmful effects.

Foreign Substance

Pollutants can be either foreign substances or a component of the original substance that has exceeded the harmless level.

Contaminants usually refer to foreign matter that are introduced from the outside.Difference Between Pollutant and Contaminant- infographic