Atmospheric Radon-222 Concentration Variation with Height and Time

Abstract

Studies of concentrations of radon-222 in the atmosphere have been made from the surface of the earth to 16 meters elevation for eight periods of approximately 24 hours each. These studies provide over 650 individual determinations of radon concentration measured during a wide variety of meteorological conditions, from clear days with high radiation and relatively weak winds to cloudy days of low radiation and relatively high winds. Information presented indicates general features of radon concentration: 1) highest concentrations near the soil, the source, 2) maximum concentrations at night with the maximum near the soil occurring about 3 hours before the maximum at 16 meters, 3) minimum values at all levels near midday, 4) almost constant concentration with elevation, indicating good mixing during morning hours, and 5) the increase of concentration at ground level ahead of those aloft with the approach of evening. Average 24-hour exposure at human breathing level, between 1 and 4 meters, varies between 0.259 and 0.301 picocuries per liter at the Argonne National Laboratory site.