Radon exhalation

This application note describes how to simply and quickly quantify Radon exhalation on surfaces using a Radon-monitor like RTM1688-2 or RTM2200 from SARAD GmbH and an exhalation bonnet.

Physical Basics

The quantifying of Radon exhalation on surfaces is based on observing the increase of Radon activity concentration related to a well-defined gas volume until a steady concentration level is obtained in a certain time.

The Radon flux (or exhalation rate) E [Bq / (m²s)] on a surface is defined as ratio of (Radon-) activity A [Bq] to a Radon exhalating surface area (area F [m²]) and a durance t [s]:

1) E = A / (F * t) [Bq / (m²s)]

Consider an exhalation bonnet with the shape of a rectangular solid or a cylinder and with covered area F [m²] and height h [m], also with volume V :

2) V = F * h [m³]

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