Factorio wiki-Pollution

Pollution is represented as an abstract "cloud" are calculated for each chunk and visible on the minimap and map an alternate mode is enabled (in the original setting is enabled on Alt)
Contamination occurs at the expense of many of the buildings involved in the processing and manufacturing of goods, and distributed through an area with constant speed.
Impact on the local fauna.
• Pollution attracts Bitters. Bitters, the affected areas will strive to achieve pollution source of pollution and destroy it.
• Spaunery absorb pollution thus increasing evolutionary factor.
Abatement methods.
• Slowly (0.6 units per tick pollution) each chunk (32 x 32), pollution, reduces its pollution (cleans). Thus, the larger the area, prone to contamination, the more pollution is absorbed.
• Trees also absorb part of pollution (see. Tabicu zgarjaznenija)
• Spaunery absorb part of the pollution, but it adds complexity while increasing the evolutionary factor game.
• Some modifications allow you to construct a device or plant trees that reduce pollution artificially.

Modules.

Modules, which are in the description of the property "+ x% of pollution increase multiplier pollution rather than pollution directly. The resulting contamination produced by building is calculated as (multiplier of pollution x Multiplier x Baseline energy consumption, pollution). Thus, buildings with most modules are most likely will produce the most pollution.