Polluted Dirt

Polluted Dirt is a solid element commonly encountered and produced throughout a colony. It is created as a by-product of several processes (outhouses, Ethanol Distillers, Water Sieves, Pacu excretion, and certain critter diets) and can also be harvested from some Space POIs. Polluted Dirt will passively emit Polluted Oxygen when exposed to low ambient gas pressure, and this behavior drives many of the ways players must handle, store, or dispose of it.

Polluted Dirt is produced by multiple systems: Outhouses convert Dirt into Polluted Dirt each use; Ethanol Distillers output Polluted Dirt alongside Ethanol and Carbon Dioxide when processing Lumber; Water Sieves generate Polluted Dirt as a by-product when filtering Polluted Water with Sand or Regolith; Pacus and some other critters excrete Polluted Dirt after consuming Algae; Sludge Presses can convert Polluted Mud into Polluted Dirt and Polluted Water (production speed depends on the operator’s Machinery skill); certain rocket POIs (e.g., Swampy Ore Fields) contain harvestable Polluted Dirt in large quantities. Polluted Dirt can be processed into Dirt in a Compost, eaten by critters such as Sage Hatches (which excrete Coal) and Pokeshells (which excrete Sand), or converted to Polluted Oxygen at a Sublimation Station.

A key mechanical property of Polluted Dirt is its tendency to emit Polluted Oxygen when not kept under sufficient pressure. If the surrounding gas pressure is below 1.8 kg/tile (1800 g), Polluted Dirt loses mass while releasing Polluted Oxygen. The emission rate (in g/s) scales with the square root of the Polluted Dirt mass (in kg) and follows the formula:

• rate = 0.2 * sqrt(mass) (g/s) under base game rules. This emission can be fully prevented by either storing Polluted Dirt submerged in a liquid that provides at least 1.8 kg/tile pressure or by keeping it under a gas pressure of at least 1.8 kg/tile. In transport via Conveyor Rail Polluted Dirt will still attempt to emit Polluted Oxygen, but at a much reduced frequency compared to open storage; Polluted Dirt carried by duplicants does not emit while being carried, though interruptions to the hauling job can create edge cases where emissions occur.

In the Spaced Out (DLC) version the emission rate is reduced by a factor of ten:

• rate = 0.02 * sqrt(mass) (g/s).

Practical usage and handling notes:

• Store Polluted Dirt submerged in water (or under high gas pressure) to prevent uncontrolled Polluted Oxygen release. Submerging also prevents the soil from displacing the liquid if the liquid column provides the required pressure.
• Use Compost to convert Polluted Dirt back into Dirt for agricultural reuse. Composting is an efficient way to reclaim some of the resource.
• Feed Polluted Dirt to critters that accept it (Sage Hatches, Pokeshells) to produce useful by-products (Coal, Sand).
• Convert large piles into Polluted Oxygen on purpose with a Sublimation Station if you need a controllable gas source, or use Sludge Presses to reclaim materials from Polluted Mud.
• When excavating large deposits (for example on Space POIs), plan containment: large masses of Polluted Dirt can rapidly raise local Polluted Oxygen levels if left at low pressure. In the Spaced Out DLC emissions are slower but still require attention.
• Polluted Dirt’s emission rate depends on exposed perimeter or effectively on the square root of mass when stored; spreading mass into multiple smaller stacks increases total emission slightly due to perimeter effects, so centralized containment under pressure is preferable.

Because Polluted Dirt interacts with atmospheric pressure and liquids, its behavior influences base layout decisions around storage, waste processing, and critter farming. Managing its emissions early prevents Polluted Oxygen buildup and loss of mass, and utilizing its conversion pathways can turn a nuisance by-product into useful resources.