A person writing on a printed sheet at a desk in raking sunlight

CleanZone Method

Setting Your Own Non-Negotiables

Most relocation research starts backwards: open a map, scroll around, feel a vague dread or relief about a neighbourhood, repeat. That process never terminates, because "feels fine" has no stopping rule. The fix isn't more data. It's deciding, in advance and in writing, exactly what number ends the conversation for each factor, before you look at a single postcode.

A threshold table is a personal pass or fail line for every factor you care about, written down while you are still capable of walking away from a kitchen you like. Every number in it should trace back to a published standard: WHO, EPA, EU Euratom, USGS, FEMA. A gut feeling or a forum post will not survive the month you spend arguing with yourself.

Hard gates eliminate a candidate outright when crossed. Soft preferences get weighted into a score and never disqualify on their own. Mixing the two, treating every preference as a gate or every gate as negotiable, is why relocation research runs for months and ends in nothing. Build the table once and reuse it; a ready-made version lives at the printable checklist.

40
dB L_night
WHO night-noise guideline for the European Region
300
Bq/m³
EU Euratom indoor radon reference level
1%
AEP
FEMA / EU threshold defining a regulatory floodplain
RADON REFERENCE LEVELS BY JURISDICTION (Bq/m³) 100 WHO guidance 200 UK action level 148 US EPA (4 pCi/L) 300 EU Euratom Higher bar = looser reference level; same risk
Public radon reference levels compared on one axis (Bq/m³; US EPA's 4 pCi/L converted at 1 pCi/L = 37 Bq/m³). Sources: WHO Handbook on Indoor Radon; UK radon target; US EPA action level; EU Directive 2013/59/Euratom. A tighter personal threshold than any of these is a legitimate choice; a looser one than the strictest public line needs justifying.
Twelve hard gates returns zero

A threshold table with twelve hard gates is not a stricter search, it's a search that returns zero results, because no real property clears every regulator's guideline value simultaneously. Reserve hard-gate status for the handful of factors where crossing the line has a genuine, named consequence for your household. Everything else belongs in the weighted column.

Anxiety about a place is usually just an undefined stopping rule wearing a trench coat.

Using the table against real candidates

Once the table exists, evaluating a candidate location is mechanical: pull the relevant public figures or grid fields for the address: pm25, noise, radon, hardness, flood zone, flights, and run each one against your row. Any hard gate crossed removes the candidate immediately, no further comparison needed. Everything that survives the gates gets scored on the soft preferences, and that score is what you actually compare between the two or three places left standing. This is the same logic behind CleanZone's own the printable checklist; a ready-made version of this exercise you can fill in per candidate rather than rebuild from scratch each time.

Without a table

Every viewing reopens the whole decision. A nice kitchen quietly outweighs a radon reading nobody actually tested. "Feels safe" substitutes for a number. The search has no defined end, so it runs for a year.

With a table

Gates are checked first and are non-negotiable, in five minutes, before a viewing is even booked. Preferences get scored instead of argued about. The search ends when a candidate clears every gate and scores highest on the rest.

Keeping it honest

Two disciplines keep a threshold table from quietly rotting. First, revisit it only when your household's actual circumstances change (a new asthma diagnosis, a planned basement conversion, a pregnancy) not because one property you liked happened to fail a gate. Moving the goalposts to fit a house you've fallen for defeats the entire purpose. Second, write the source next to every number. "300 Bq/m³ (EU Euratom)" survives a memory lapse eight months later; "300" alone does not, and you'll find yourself unable to defend (or even recall) where it came from.

A threshold table doesn't make a place safer. It makes the decision about that place fast, defensible, and yours, built once from public standards (pm25, noise, radon, hardness, flood zone), then reused against every candidate. Start one at the printable checklist.

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