Scores 0–100 (100 = cleanest) using two layers:

1. EPA Registers — VIC Priority Sites Register, NSW Contaminated Land, WA DWER database. Official government records of confirmed or suspected contamination.

2. Industrial Proximity — Overture POI data for fuel stations, chemical plants, auto repair, dry cleaners, waste facilities within 500m.

QLD, SA, TAS, ACT, NT rely on industrial proximity only (no public EPA API).