Radon in County Offaly: what the EPA map shows

About 5.6% of County Offaly's land lies in 10 km grid squares the EPA rates as High Radon Areas — the 25th highest share of Ireland's 26 counties. Most of the county is lower risk, but radon is measured house by house, and the rating changes from one square to the next.

What a High Radon Area is

The EPA's radon map divides Ireland into 10 km grid squares and predicts, for each, the share of homes whose radon level is above the national reference level of 200 becquerels per cubic metre. Where that share is 10% or more, the square is a High Radon Area. In County Offaly that applies to a minority of the land, and about 2.8% of the county sits in squares where one home in five or more is predicted to be above the reference level.

A rating describes the area, not the house. Two homes on the same road can measure several times apart, depending on the ground beneath them, the floor and how the house is ventilated. The map tells you how likely a high reading is; a three-month test tells you what the house actually measures.

How Offaly compares

• Carlow83.9%
• Sligo70.3%
• Wicklow56.9%
• Waterford52.6%
• Wexford52.4%
• Kilkenny49.4%
• Mayo46.7%
• Galway45.3%
• Clare38.3%
• Louth35.8%
• Meath34.3%
• Westmeath34%
• Roscommon26.3%
• Longford25.9%
• Kildare24.1%
• Laois22.4%
• Cork21.8%
• Limerick15.9%
• Tipperary15.7%
• Kerry11.3%
• Donegal11.2%
• Monaghan8.5%
• Leitrim8.4%
• Cavan6.7%
• Offaly5.6%
• Dublin4%

What it means for a purchase

High radon is fixable: a sump and a small fan bring most homes under the reference level, and homes built since 1998 should already have a radon barrier, with a standby sump in High Radon Areas. The cost is modest against the price of a house, but it is a cost to know about before you bid. Ask for any existing test result, check what protection was fitted, and budget for a test after you move in.

Figures: the EPA Radon Risk Map (CC BY 4.0), 868 grid squares. Each square was sampled on a 1 km lattice and every sample placed in a county by its electoral division, so a county's figure is the share of its land in High Radon Areas, not a count of squares that touch it.

How a VeriSale report checks it for one address

VeriSale looks up the EPA radon map for the property’s coordinates and reports the predicted percentage of homes above the reference level in that grid square.

• High Radon Area (10% or more of homes predicted above the reference level)Flagged, with the percentage: “High radon area (~22.0% of homes above the reference level) — test and check for protection.” The grade falls as the percentage rises.
• Lower riskReported as lower risk with the percentage, graded well.
• No estimateThe report says so rather than guessing.

This is one of 39 checks in the report, each graded A–F with a plain-language summary. The report compiles public data; it is not a survey or legal advice. More about radon and how to read it.

What to ask before you bid

• Has the home ever been tested for radon, and can the seller share the result?
• When was the house built, and does it have a radon barrier or a sump? (Required in new builds since 1998.)
• If a sump is fitted, is a fan connected, and is it running?

Frequently asked questions

More on County Offaly

Buying a house in Offaly: the full county guide

Radon in other counties