Measurement of indoor and outdoor radon concentrations during Superstorm Sandy.

Superstorm Sandy affected much of the US East Coast extending over 1800 km. It passed over the test location in the State of Maryland on 29 October 2012. Being 350 km away from the regions of highest intensity the storm was of lower intensity at the test location. Continuous radon monitors and passive radon monitors were used for the measurement. The test location was the basement of a single family home representing the indoor concentration. A partially opened garage of the same test home represented the outdoor radon concentration. In 24 h, the atmospheric pressure dropped from 990 to 960 mbar and the indoor radon concentration increased from 70 to 1500 Bq m(-3) and returned to the normal of 70 Bq m(-3) at the end of the storm. Throughout the storm, the outdoor radon concentration was not significantly affected. Probable reasons for such surprisingly large changes are discussed. However, the outdoor temperature dropped from 13°C to 7°C during the radon peak.