Is Platte County, MO a radon risk area?

EPA's own radon map rates Platte County zone 1 - highest potential, predicting a county-wide average indoor level above 4 pCi/L. Platte County sits at the 94th percentile nationally for radon potential — above 94 of every 100 rated counties.

How Platte County compares

About 113,207 people live in Platte County, Missouri, spread over 419.823 square miles. Averaged across its land area, Platte County runs about 270 people per square mile. Rank 175 by population within its EPA zone puts Platte County at the 84th percentile among zone peers. EPA's geology-based Region 7 groups Platte County with 411 other counties nationally sharing its underlying rock and soil profile.

Zone vs. an actual test

Fixing a home becomes an EPA recommendation past 4 pCi/L, and that is precisely the side of the line Platte County's Zone 1 prediction lands on, well above the roughly 1.3 pCi/L most US homes average. Being in Zone 1 raises the odds Platte County homes test above the action level, but it does not mean any specific house does — EPA recommends every home be tested, in every zone, because the only way to know is to test.

If Platte County tests above the action level

Nothing about Platte County's EPA zone changes the mitigation number: $800–$2,500 nationally (around $1,200 typical), set by the house's foundation rather than the county it sits in — and only relevant once a test actually clears 4 pCi/L.

Find Missouri's state radon program

Platte County's test kit answers today; a Airthings radon monitor keeps answering for Platte County over time. Affiliate link, RadonZoneCheck earns a commission there, at no extra cost to you. Code RADONZONE-10OFF takes 10% off at checkout.

More on how this number was built

The methodology guide shows exactly which EPA and Census sources feed Platte County's numbers. Whatever zone Platte County carries, the zone explainer covers what it does and doesn't tell you about any one house.