Is Howard County, MD a radon risk area?
EPA's own radon map rates Howard County zone 1 - highest potential, predicting a county-wide average indoor level above 4 pCi/L. Howard County sits at the 98th percentile nationally for radon potential — above 98 of every 100 rated counties.
How Howard County compares
About 339,668 people live in Howard County, Maryland, spread over 250.95 square miles. Averaged across its land area, Howard County runs about 1,354 people per square mile. Rank 68 by population within its EPA zone puts Howard County at the 94th percentile among zone peers. Geologically, Howard County is grouped into EPA Region 3 alongside 244 other counties that share its rock and soil setting.
Why the zone isn't the answer by itself
Fixing a home becomes an EPA recommendation past 4 pCi/L, and that is precisely the side of the line Howard County's Zone 1 prediction lands on, well above the roughly 1.3 pCi/L most US homes average. A Zone 1 rating means testing is worth doing sooner rather than later, but it is still county-wide average, not a reading for any single house — some homes in Howard County will test well under the action level, and EPA's guidance is to test regardless of zone.
If Howard County tests above the action level
Nothing about Howard 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 Maryland's state radon program
Howard County's test kit answers today; a Airthings radon monitor keeps answering for Howard County over time. Affiliate link, RadonZoneCheck earns a commission there, at no extra cost to you. RADONZONE-10OFF at checkout knocks 10% off.
More on how this number was built
Howard County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.