Pollution

Example of ingame pollution (red squares) in the map

Pollution is represented as an abstract "cloud", updated per chunk every game second (60 ticks) and visible on the minimap and Map, when Alternative view is on (default Alt-Key).

It is produced by many buildings involved in processing items and spreads outwards at a steady rate.

The evolution factor is not increased by the spreading/absorbed pollution, but by the pollution produced by all the Player's machinery at every tick. The pollution cloud is used to trigger biter attacks and determines the size of the attacks.

Achievements

Main article: Achievements

Pollution is directly connected to the following achievement:

It stinks and they don't like it: Trigger an alien attack by pollution.

Pollution spread

As soon as a chunk has reached 15.0 pollution it starts spreading in all four cardinal directions at a rate of 2% game second (60 ticks).

e.g. a chunk with 400.0 pollution and 4 adjacent chunks with 100.0 pollution each, raises the pollution in all adjacent chunks by 8.0 while reducing its own pollution by 32.0. But everyone of the 4 surrounding spreads 2.0 pollution "back" to the center chunk, so it only loses 24.0 + absorbed value.

Pollution dissipation

Every Chunk (32x32) of map slowly reduces the pollution it covers (See Pollution Production#Chunks). So the more the pollution spreads, the more is absorbed.
Trees also absorb some pollution (See Pollution Production#Trees).
Spawners absorb a great amount of pollution.
In certain Mods it is possible to build devices or trees which reduce pollution.

Native life

Pollution attracts biters to the Player's factory. Biters who find themselves in a polluted area will attempt to reach the source of pollution and destroy it.

Each spawner absorbs 20 + 0.01 * [chunks pollution] every game second (60 ticks), if the chunks pollution is greater than 20 otherwise it absorbs the total pollution.

Higher pollution values decrease the time it takes for biters to join the attack force. After a certain amount of pollution is absorbed the spawner sends one of its biters/spitters to a rendezvous point. Every 1 to 10 minutes (random) the mustered biters launch an attack. If not all biters have arrived at the rendezvous point by that time, they will wait up to an additional 2 minutes for stragglers.

Required pollution to add an additional biter/spitter to the attack wave:

Pollution	Type
200	Small biter
1000	Medium biter
4000	Big biter
20000	Behemoth biter
200	Small spitter
600	Medium spitter
1500	Big spitter
10000	Behemoth spitter

With 1350 absorbed pollution at the time of attack the following wave consists of 6 small biters and 1 medium biter OR 6 small spitters and 2 medium spitters depending on the spawner's type and evolution factor.

Modules

Modules that list "+x% pollution" increase pollution multiplier, not a flat pollution rate. Final pollution value is (pollution multiplier * energy usage multiplier * base pollution), meaning heavily boosted buildings are likely to account for most of the pollution produced in a factory.

Production

These tables contain information about the levels of pollution produced/absorbed by items in the game.

Polluters

Object	Pollution per KW per game second (60 ticks)	Pollution per game second at full power
File:Stone-furnace.png Stone furnace	0.01/KW	1.8
File:Steel-furnace.png Steel furnace	0.02/KW	3.6
File:Electric-furnace.png Electric furnace	0.005/KW	0.9
File:Burner-mining-drill.png Burner mining drill	0.03333/KW	9.999
File:Electric-mining-drill.png Electric mining drill	0.1/KW	9
Pumpjack	0.1/KW	9
File:Assembling-machine-1.png Assembling machine	0.03333/KW	2.9997
File:Assembling-machine-2.png Assembling machine 2	0.016/KW	2.4
File:Assembling-machine-3.png Assembling machine 3	0.00857/KW	1.7997
File:Small-pump.png Small pump	0.004/KW	0.12
Boiler	0.01538/KW	5.9982
File:Oil-refinery.png Oil refinery	0.00857/KW	3.5994
File:Chemical-plant.png Chemical plant	0.00857/KW	1.7997

De-polluters

Spawner

If a chunk's pollution is greater than 20, each enemy spawner absorbs 20 + 0.01 * [chunk's pollution] every game second (60 ticks), otherwise it absorbs the chunk's total pollution.

Chunks

Every chunk has a natural absorbtion rate per tick which is determined by the weighted average of its floor tiles.

Following numbers are the pollution reduction for a full chunk (32x32 tiles) composed of the same floor tiles per tick.

Tile	Pollution per tick	Pollution per second
Dark sand	-0.0033	-0.2
Sand	-0.0042	-0.25
dry grass	-0.0066	-0.4
medium dry grass	-0.0075	-0.45
grass	-0.0075	-0.45
dirt	-0.0075	-0.45
dry dirt	-0.0075	-0.45
Green water	-0.0083	-0.5
Deep green water	-0.0083	-0.5
Water	-0.0100	-0.6
Deep water	-0.0100	-0.6
Stone floor	0.0	0.0
Concrete	0.0	0.0

Pollution per tick resembles the third number in the pollution debug information (which is missing the 5th digit)

Trees

Every single tree absorbs a small amount of pollution in its chunk per tick.