Local Pollution

Local Pollution

A busy freight yard on the edge of town shouldn't count the same as one beside people's homes.

Local Pollution makes the pollution rating used for town growth depend on where residents live. It checks pollution at residential buildings, so keeping industry, stations and other polluting infrastructure away from housing can make a real difference—even if they are still inside the town boundary.

It doesn't remove pollution or guarantee faster growth. Noise, deliveries, happiness and the other town ratings still matter.

What changes when you enable it?

The game normally rates pollution across the municipal area. Local Pollution instead checks where the homes are. A freight terminal far from housing can have a smaller effect on the town's rating, while pollution beside homes still matters. The emissions themselves stay the same.

A higher pollution rating means a cleaner, better-rated town. It does not mean there is more pollution. The new rating feeds the existing town authority and growth system. Another weak rating, such as noise or deliveries, can still hold growth back.

The town-window pollution rating

The pollution label and rating-tab icon read the pollution rating cached by the simulation, so they describe the rating used for town growth. The 0.3.5 display fix has been confirmed working in-game. Version 0.3.6 also removes the Pollution tab's advice about keeping the whole municipality clean when Residential exposure is selected, since the mod rates residential exposure instead. Diagnostic only mode keeps the game's original display and advice.

The graph shows previously recorded ratings and can lag behind the current grade. After loading, allow the simulation to measure the town and complete its normal town update. If the cached rating is unavailable, the original grade is retained.

Notifications keep the game's normal rules. An existing severe warning can remain when the rating improves from Very Poor to Poor; it clears after further improvement. Other tabs' advice and the pollution overlay's town labels are unchanged.

The source percentages and map colours describe different things: the percentages show each source's share of municipal emissions; the overlay shows emissions and absorption on the map. They do not show how much of the residential rating comes from each source. “Stations 26%” does not mean homes are 26% polluted.

Choosing your settings

64 samples is the default. You can choose 32 for fewer checks, or 128 for wider coverage in larger towns. More samples can move the result in either direction; this is a coverage setting, not a difficulty slider. Small towns use every eligible home when they fit within the chosen limit.

Household rating is the recommended setting. Each sampled home gets a pollution rating, and homes with more residential capacity count more toward the town's result. Strict exposure gives strong pollution hotspots more influence.

There is also a Diagnostic only option if you want to collect readings while keeping the game's original pollution calculation. Logging can be switched off in the mod settings.

After loading, let the simulation run through a full round of town measurements and the next town update. Existing saves keep their selected sample count when you update the mod.

What the screenshots show

The gallery pairs five towns from the same save: Atherstone, Portland, Leatherhead, Wadebridge and Saffron Walden. Each pair shows the town without Local Pollution, followed by version 0.3.3 with 64 samples. Compare the right-hand history graphs: higher means a better rating. Atherstone shows a large improvement; Portland shows a smaller one.

The first pictures were taken on June 24, 1986, and the modded pictures on June 30. The camera angles differ slightly and the simulation has moved forward, so these are practical examples rather than perfectly matched measurements. They show what happened in this save, not a promise that every town will improve. The screenshots are unretouched, and the live labels still show the original calculation.

Using an existing save

No new map is needed, and the mod adds no buildings, vehicles or other map assets. You can add or remove it from an existing game's mod selection and then reload the save. That change takes effect on loading, rather than instantly during a running simulation.

Removing it returns future pollution calculations to the game's original system. It doesn't undo population growth, experience or graph history already earned. Existing-save loading has been tested; the full save, disable, reload and re-enable cycle still needs testing.

Other mods

No Terraforming Reputation Loss, revision 4, is explicitly supported. No other mod is required.

Mods that replace the town simulation controller, change pollution or town authority calculations, or replace the same live rating functions may conflict. If an incompatible town controller is detected during loading, Local Pollution logs a warning and leaves that controller in place. A mod loaded later can still override these changes.

Release status

0.3.6 is prepared for preview Steam build 26129055. Residential sampling and the 0.3.5 town-window label/icon fix have been confirmed working. This update removes the outdated municipal advice box in Residential exposure mode; it passes offline checks and awaits visual confirmation. The gallery remains a record of 0.3.3. Game updates may require a mod update.