How Long Does Toxic Fallout Last in RimWorld (1.6)? | Timer + Survival Toolkit

How Long Toxic Fallout Lasts in RimWorld
and how to survive it

2.5 to 10.5 days in vanilla 1.6.4633 • plus the 24‑hour bunker checklist for colonists, crops, and animals.

Local game defs 1.6.4633 rev1266 Checked 2026-03-24 Vanilla‑first (DLC notes separated)
Quick Solution: Survive the Next 24 Hours
Situation Fastest Action Why it Works Biggest Mistake
Toxic Fallout
2.5 to 10.5 days • 150,000–630,000 ticks		 Restrict pawns & animals to roofed lanes. Roof freezer↔beds↔hospital first. The condition hurts living things not under a roof. “One more haul / harvest” exposure loops.
Toxic Spewer
Quest / condition‑causer		 Decide fast: destroy the source or commit to a long indoor economy. No normal timer if it’s a source‑causer. Waiting for a countdown that doesn’t exist.
Polluted Terrain
Biotech		 Reroute paths off polluted tiles; clean or cover the tiles in your daily loop. Roofs stop fallout exposure; the floor can still hurt. Assuming “indoors = safe”.
Odyssey Toxic Rain
Odyssey		 Treat it as a different hazard: sealed routes, indoor production, or relocation planning. Not the classic storyteller toxic‑fallout timer. Using the wrong fix for the wrong green sky.
If pawns are getting toxic buildup indoors, that’s usually a route gap or a DLC pollution tile problem, not “bugged fallout”.
Which Toxic Problem Is It?
Toxic Fallout
Timed condition: bunker + roofed routing.
Toxic Spewer
Source‑causer: ends when destroyed.
Polluted Tiles
Even roofed tiles can be toxic (Biotech).
Odyssey Toxic Rain
Different system: handle like a biome hazard.
Food Priority Table
  1. Freezer reserves (already under roof)
  2. Nutrient paste (stretch calories)
  3. Pemmican / packaged survival meals
  4. Hydroponics / indoor grow (if you already have it)
  5. Outdoor hunting (only if desperate)
Shelter Wins Before Medicine
Toxic Buildup Levels
Minor (20%+)Limit exposure
Moderate (40%+)Full indoors
Serious (60%+)Bed rest
Extreme (80%+)Emergency care
Deadly (100%+)ICU only
Gear note: Face mask (def Apparel_ClothMask) adds 50% toxic environment resistance in 1.6.4633 Core defs.
Animals to Keep or Cull
Save
  • Bonded animals
  • Breeding pairs
  • Haulers / pack animals
  • High‑value producers you can feed indoors
Cull
  • Extra grazers
  • Low‑value mouths
  • Vanity pets you can’t shelter
  • Extra males / old stock
Caravan & Quest Risk
  • Routine trade tripNO
  • Toxic spewer raid (stopping the source)MAYBE
  • Rescue mission (no timer)NO
  • Emergency food/medicine runYES
If you must go outside, use the best‑protected pawn and keep the job short.
Troubleshooting (Fast)
Data sources (local game files):
Toxic fallout timer: /game/Data/Core/Defs/Storyteller/Incidents_Map_Misc.xml → IncidentDef ToxicFallout (durationDays, minRefireDays).
Roof rule & penned animal sheltering: /game/Data/Core/Defs/GameConditionDefs/GameConditions_Misc.xml → GameConditionDef ToxicFallout.
Toxic buildup bands: /game/Data/Core/Defs/HediffDefs/Hediffs_Global_Misc.xml → HediffDef ToxicBuildup (minSeverity, lethalSeverity).
Face mask resistance: /game/Data/Core/Defs/ThingDefs_Misc/Apparel_Headgear.xml → ThingDef Apparel_ClothMask (ToxicEnvironmentResistance).
Build version: /game/Version.txt.