Bradley H. Turk

Characterizing the occurrence, sources, and variability of radon in pacific northwest homes

A compilation of data from earlier studies of 172 homes in the Pacific Northwest indicated that approximately 65 percent of the 46 homes tested in the Spokane River Valley/Rathdrum Prairie region of eastern Washington/northern Idaho had heating season indoor radon (222Rn) concentrations above the U. S. EPA guideline of 148 Bq m-3 (4 pCi L-1). A subset of 35 homes was selected for additional study. The primary source of indoor radon in the Spokane River Valley/Rathdrum Prairie was pressure-driven flow of soil gas containing moderate radon concentrations (geometric mean concentration of 16,000 Bq m-3) from the highly permeable soils (geometric mean permeability of 5 x 10(-11) m2) surrounding the house substructures. Estimated soil gas entry rates ranged from 0.4 to 39 m3h-1 and 1 percent to 21 percent of total building air infiltration. Radon from other sources, including domestic water supplies and building materials was negligible. In high radon homes, winter indoor levels averaged 13 times higher than summer concentrations, while in low radon homes winter levels averaged only 2.5 times higher. Short-term variations in indoor radon were observed to be dependent upon indoor-outdoor temperature differences, wind speed, and operation of forced-air furnace fans. Forced-air furnace operation, along with leaky return ducts and plenums, and openings between the substructure and upper floors enhanced mixing of radon-laden substructure air throughout the rest of the building.

Performance of radon control systems

Abstract Of five types of radon control techniques installed in seven New Jersey houses with basements, systems based on subsurface ventilation (SSV) by depressurization were the most effective and suitable for the long-term reduction of indoor radon levels. Small seasonal variations in substructure radon levels were observed in several houses while SSV systems were operating and may be due, in part, to changes in substructure ventilation rates from below 0.2 h−1 to approximately 0.4 h−1. Effective permeabilities for near-house materials measured at SSV pipes were an order of magnitude larger (geometric mean (GM) of 4.1 × 10−9m2) than the permeabilities of surrounding soils (GM of 1.5 × 10−10m2). Below-grade substructure surfaces appeared to have large air leakage areas as indicated by high entrainment fractions (0.41–0.92) of basement air in SSV exhausts. These leakage areas probably increased the effective permeabilities and influenced SSV flows and pressure field extensions. By sealing accessible leakage openings, greater depressurization below the slab during SSV operation was achieved in several houses, although indoor radon levels were not affected. In two houses, heating and cooling air distribution equipment caused additional substructure depressurizations ranging from 1.1 Pa to 5.4 Pa, but did not compromise radon reduction by SSV systems. Installation costs for SSV systems averaged

Effectiveness of radon control techniques in fifteen homes

2270, while estimated annual energy costs to operate fan-driven radon control systems ranged from

Developing soil gas and 222Rn entry potentials for substructure surfaces and assessing 222Rn control diagnostic techniques.

85 for houses with oil heating to

Causes and prevention of symptom complaints in office buildings

250 for electrically heated houses.

Parametric modelling of temporal variations in radon concentrations in homes

Radon control systems were installed and evaluated in fourteen homes in the Spokane River Valley/Rathdrum Prairie and in one home in Vancouver, Washington. Because of local soil conditions, subsurface ventilation (SSV) by pressurization was always more effective in these houses than SSV by depressurization in reducing indoor radon levels to below guidelines. Basement overpressurization was successfully applied in five houses with airtight basements where practical-sized fans could develop an overpressure of 1 to 3 Pascals. Crawlspace ventilation was more effective than crawlspace isolation in reducing radon entry from the crawlspace, but had to be used in conjunction with other mitigation techniques, since the houses also had basements. Indoor radon concentrations in two houses with air-to-air heat exchangers (AAHX) were reduced to levels inversely dependent on the new total ventilation rates and were lowered even further in one house where the air distribution system was modified. Sealing penetrations in the below-grade surfaces of substructures was relatively ineffective in controlling radon. Operation of the radon control systems (except for the AAHXs) made no measureable change in ventilation rates or indoor concentrations of other measured pollutants. Installation costs by treated floor area ranged from approximately

COMMERCIAL BUILDING VENTILATION RATES AND PARTICLE CONCENTRATIONS

4/m2 for sealing to

Evaluation of Radon Mitigation Systems in 14 Houses Over a Two-year Period

28/m2 for the AAHXs. Based on the low electric rates for the region, annual operating costs for the active systems were estimated to be approximately

The effects of infiltration and insulation on the source strengths and indoor air pollution from combustion space heating appliances

60 to

Pacific Northwest existing home indoor air quality survey and weatherization sensitivity study: Final report

170.