New York State Studies (published)
Radium-free standards are not readily available for proficiency testing of laboratories that conduct radon (222Rn) analyses of water. For this study, 33 identical, reusable, radon-in-water standards were prepared using a 226Ra-loaded filter sandwiched in polyethylene sheeting. The 222Rn concentrations in the 226Ra-free standards were measured by liquid scintillation counting and compared to 10 reference solutions containing 226Ra. The 222Rn concentrations measured in the standards were consistent (standard deviation of <2%), but averaged substantially less than concentrations determined in the 226Ra reference standards. At full ingrowth, 86% of the 222Rn produced by the sandwiched 226Ra sources emanated into the water. An intercomparison of radon-in-water standards, performed to examine the accuracy of analyses by commercial, government, and private companies, showed that 18 of the 21 participants reported concentrations within 25% of the known (693 Bq l-1).
Decorative stones (32 natural and 18 manufactured) and 5 ceramic tiles that are used in home interiors were measured with gamma-ray spectrometry, to identify and quantify the naturally occurring radionuclides. Activity concentrations of the radioisotopes varied by more than two orders of magnitude across the stone samples, with maximal levels of 3380, 850, and 2130 Bq/kg, for 238U, 232Th, and 40K, respectively. A radiation index and measurements with a radiation meter established that the annual effective dose rates due to a 1 hr/d exposure to gamma rays emitted by the granite samples were often low, but can occur as high as 1 mSv/yr.
Abstract - Emanation of Radon from Household Granite
Emanation of radon (222Rn) from granite used for countertops and mantels was measured with continuous and integrating radon monitors. Each of the 24 granite samples emitted a measurable amount of radon. Of the two analytical methods that utilized electret-based detectors, one measured the flux of radon from the granite surfaces, and the other one measured radon levels in a glass jar containing granite cores. Additional methods that were applied utilized alpha-scintillation cells and a continuous radon monitor. Measured radon flux from the granites ranged from 2 to 310 mBq m-2 s-1, with most granites emitting <20 mBq m-2 s-1. Emanation of radon from granites encapsulated in airtight containers produced equilibrium concentrations ranging from <0.01 to 11 Bq kg-1 when alpha-scintillation cells were used, and from <0.01 to 4.0 Bq kg-1 when the continuous radon monitor was used.
Abstract - Mapping of Indoor Radon Potential at the Township Level
A combination of approximately 51,000 basement-screening measurements, 6,500 long-term measurements, and correlations to surficial geology was used to develop radon maps on the township level that indicate the percentage of homes with >148 Bq m-3 (4 pCi L-1) in the indoor air of basements and living areas. The indoor radon geometric mean concentration and geometric standard deviation of the mean were estimated for all towns in New York State, using both empirical and Bayesian regression techniques to combine surficial geology correlations with the measurement data. For the 342 towns with >30 measurements, results obtained using the two methods were equivalent (r2=0.96). Over 50% of the houses in 212 towns contain basement-level radon concentrations >148 Bq m-3. Results of long-term living-area radon risk estimates and an earlier random survey results agreed within 20%, demonstrating that the maps can be used to reliably assess residential radon exposure. For the single county examined, a strong correlation (r2=0.96) of soil permeability with radon concentration demonstrated the utility of soil survey maps for estimating radon potential.
Abstract - Performance of a Commercial Radon-in-water Measurement Kit
Methods currently approved for the measurement of radon (222Rn) in water in New York State are liquid scintillation counting and emanation into alpha-scintillation cells. A passive system using an electret ion chamber (EIC) was evaluated as an alternative for the measurement of radon in water. Over 130 water samples from a community water supply containing 32 Bq L-1 and 30 standards containing 686 Bq L-1 were measured using the EIC method over 1- to 4-day exposure times. For comparison, identical samples were measured using liquid scintillation counting. Results of duplicate samples were typically within 5% for liquid scintillation counting and within 10% for the EIC. With respect to accuracy, the EIC produced results that were consistently low by 11-15%.
Abstract - Assessment of the Multimedia Mitigation of Radon in New York
Although not yet implemented, the 1996 amendments to the Safe Drinking Water Act instructed the states (or local water suppliers) to address radon concentrations in community water systems (CWS). As an alternative to reducing waterborne radon concentrations in the CWS to the maximum contaminant level (MCL) of 11 Bq/L, states (or individual CWS) would be permitted to develop a multimedia mitigation (MMM) program, which allowed a greater concentration (148 Bq/L) of waterborne radon in the CWS, if it could be shown that an equivalent health risk reduction could be achieved by reducing indoor radon concentrations. For a MMM program to be acceptable, the U.S. Environmental Protection Agency required the health-risk reduction attained through mitigations and radon-resistant new construction (RRNC) to offset the increased health risk due to radon in community water systems above the MCL of 11 Bq/L. A quantitative assessment indicates that the reduction in health risk currently achieved in New York State through radon mitigations and RRNC exceeded the increase in risk associated with an alternative MCL of 148 Bq/L. The implementation of a MMM program in New York would result in an overall reduction in the health risk associated with exposure to radon.
Abstract - Interrelationship of Indoor Radon Concentrations, Soil-Gas Flux, and Meteorological Parameters
Passive electret-based radon flux monitors were deployed at 12-hr intervals for 1 year outside a single-family house, in order to access the variability and reliability of this method for estimation of indoor radon concentrations. Radon flux from the soil averaged 37 mBq/m2-sec and showed small diurnal and seasonal fluctuations. Continuous basement-level radon measurements were collected at 5-min intervals during the same time period, inside the house. The corresponding measurements allowed a direct comparison of the relationship of radon flux from the soil, using this method, and actual indoor radon concentrations at the house. Indoor radon levels showed strong diurnal and seasonal cycles, with the indoor radon concentrations during the year ranging from 50 to 1570 Bq/m3 and averaging 360 Bq/m3. Meteorological measurements (barometric pressure, wind speed, temperature, and rainfall) collected at the site provided additional potentially correlative parameters to radon flux and indoor concentrations. While indoor radon levels at the house were not obviously affected by barometric pressure and wind speed, they were found to be strongly influenced by indoor and outdoor temperature differentials.
Abstract - Assessing Radon Concentrations in Areas with Few Measurements
The New York State Department of Health has estimated and mapped radon concentrations for every town and city in the State. Since for many towns there are few indoor radon measurements, the radon estimates for these towns were determined using correlations to surficial geology. A project was conducted to target towns for additional measurements that currently have few data but, based on the surficial geology of the town, are estimated to have elevated levels of indoor radon. The objective of the project was to obtain at least 30 additional measurements for the targeted towns and to compare the measurement results with the estimates based on geology. The study completed 1606 radon measurements from 9080 detector applications mailed to home owners in 94 underserved towns spread throughout the State. Of the 1115 basement measurements, 43% exceeded 148 Bq m-3, with a maximum of 6900 Bq m-3. Three homes measured in one town had radon concentrations above 2900 Bq m-3. Of the 491 living-area measurements, 19% exceeded 148 Bq m-3, with a maximum of 2700 Bq m-3. About 60% and 86% of measurement results were within one standard deviation and a factor of two, respectively, of estimated concentrations. Results indicate that regardless of the magnitude of radon potential, the estimates are in good agreement with measured concentrations.
Abstract - Development and Distribution of Radon Risk Maps in New York State
Radon maps for each county in New York State have been developed on the township level indicating the percent of homes with >148 Bq/m3 (4 pCi/L) in the indoor air of the basement and living area. Estimates are based on a combination of nearly 45,000 basement-screening measurements and correlations to surficial geology. Many of the towns and cities in the State with the highest average indoor radon concentrations are located on highly-permeable gravelly soils formed during the retreat of the Wisconsinan Glaciation. As many towns (32% of total) had <5 measurements, a project to obtain additional measurements in high-risk towns produced results comparable to estimates based on correlations to surficial geology. Radon risk maps for each county have been distributed to municipal governments, schools, and professionals in activities related to homes, buildings, and indoor air quality.
Abstract - Radon Awareness, Testing, and Remediation Survey Among New York State Residents
Between November 1995 and January 1997, a radon awareness, testing, and remediation survey was conducted to measure general awareness and factual knowledge about radon and prevalence of radon testing and remediation among New York State residents. The survey found that 82% of 1,209 respondents had heard of radon, but only 21% were knowledgeably aware of radon. With regard to radon testing, only 15% of respondents who were aware of radon had their homes tested. The percentage of respondents who were aware or knowledgeably aware of radon increased with increasing education level. The findings from the study suggest that the New York State public awareness programs that targeted high radon areas did show some effect both by increasing public awareness and promoting residential testing. The relatively low percentage of respondents who were knowledgeably aware of radon and the low percentage who had tested their homes strongly suggest that renewed efforts by the public health community are needed to increase knowledge about radon and its health effects and to encourage radon testing and remediation.
Abstract - Radon Measurements and Mitigation at a Fish Hatchery
Groundwater radon concentration of 83 Bq L-1 generated indoor radon levels exceeding 3300 Bq m-3 at a commercial fish hatchery. Passive and active mitigation strategies to reduce the waterborne radon levels included a packed column, a waterfall through perforated grates, surface aeration, and bottom bubblers. Waterborne concentrations were reduced up to 83% using a combination of mitigation procedures, but a comparable reduction in indoor radon concentrations was not observed. A diurnal cycle showed that indoor radon levels peaked in early afternoon, probably as a result of warmer air being dissolved in the water during mitigation. Reduction of indoor radon levels below 148 Bq m-3 was seldom achievable with both water mitigation and direct air ventilation at 23 room air changes hourly.
Abstract - Soil Characterization for Indoor Radon Potential at Eighteen Schools in New York State
During the two school years between 1991 and 1993, 60 schools were measured for indoor radon in New York State. Schools were solicited from areas considered to be at risk for above-average indoor radon based on residential indoor radon measurements and on the geology of the area. Eighteen of the sixty schools participating in the New York State study were selected for soil-radon potential characterization. Soils near the perimeter of the school, in the school yard, and in crawl spaces were measured for soil 226Ra concentration, soil-gas 222Rn concentration, and permeability for gas flow. In general, above-average indoor radon concentrations in the schools were found to correlate with highly permeable, gravelly soils. At 10 schools, the average soil permeability for gas flow was greater than 3s tested in these 10 schools had long-term indoor radon concentrations greater than 150 Bq/m3. The soils near the 10 schools were generally glacial outwash gravel deposits containing average concentrations of 226Ra and soil-gas 222Rn.
Abstract - Radon and Thoron Emanation from Uranium-glazed Tableware
Emanation of radon and thoron gas from souvenir housewares and construction materials was determined using alpha-scintillation cells. Though gamma-ray spectroscopy noted significant uranium concentrations in the housewares, no radioactive gas emanation was observed. Radioactive disequilibrium of the 238U and 235U decay series exists in the housewares. The 232Th decay series is in radioactive equilibrium in the housewares at concentrations several orders of magnitude lower than 238U levels. The decay series are in radioactive equilibrium in the construction materials, but only the cement block emanated a significant amount of radon.
Abstract - Direct Comparison of Three Methods for the Determination of Radon In Well Water
Radon concentrations obtained using a bubbler device developed to collect and bubble water samples in the laboratory and field were compared with results from conventional liquid scintillation counting. Measurements from standard solutions with a wide concentration range showed excellent agreement between liquid scintillation and results obtained using the bubbler device in conjunction with alpha-scintillation cells. Measurements of waterborne radon concentrations in 110 community and private wells in New York State ranged from 1 to 4100 Bq L-1, with arithmetic and geometric means of 200 and 30 Bq L-1, respectively. Excellent agreement between the analytical techniques was obtained for each field site.
Abstract - Radon Measurements in Groundwater
A device was developed for the collection, containment, and bubbling of radon from groundwater samples to facilitate concentration measurements in the field without the need for fragile glassware. Wellwater supplies were collected in high-potential areas of New York State in a comparison of the device with traditional methods (liquid scintillation and laboratory-based Lucas-cell counters). Waterborne radon levels to 4100 Bq L-1 reveal the potential contribution to indoor air from everyday water use in a home, as levels of 1500 Bq L-1 contribute about 150 Bq m-3 (the EPA-recommended limit) to indoor-air radon levels. With a Geographic Information System (GIS), spatial coordinates from each site are used to correlate concentrations with bedrock geology.
Abstract - Characteristics of Liquid Scintillation Analysis of Radon in Water
Because liquid scintillation (LS) counting will be the preferred analytical method following the forthcoming announcement of a maximum contamination level for waterborne radon in the U.S., a study was conducted using LS counting to examine the effects of cap-liner type, fluid type, agitation time, dark adaption, quench, and water-to-fluor ratio on radon measurements. Understanding the influence of these components can eliminate radon losses, decrease detection limits and increase accuracy. Application of LS to radon standards and 100 wellwater samples showed it to provide consistent results over a wide range of concentrations and decay times.
Abstract - Influence of Surficial Soil and Bedrock on Indoor Radon in New York State Homes. Task 2, Subtask 2 of an Investigation of Infiltration and Indoor Air Quality in New York State Homes
Radon can enter a building from soil and bedrock through cracks or openings in the basement. Extrapolation from data obtained from studies of miners exposed to high concentrations of radon and other carcinogens over long periods indicates that radon gas in the home poses an increased risk of lung cancer. The project was initiated to determine the characteristics of soil and bedrock that contribute to the availability of radon for infiltration into the home, and the feasibility of using soil characteristics in mapping areas at higher risk for above-average indoor radon in New York State. After conducting soil surveys across the State, the researchers choose four areas for further study. Fifteen homes in each area were tested for indoor air concentrations of radon, air infiltration into the home, radon concentrations in the soil, and the permeability of the soil for gas flow. The researchers concluded that these parameters could be combined to obtain a Radon Index Number to predict mean indoor radon levels for a given area with similar soil geology. However, this measure has a limited ability to predict indoor radon levels for a particular home due to variations in construction as well as differences in soil and bedrock.
Abstract - Radon Source Rate Measurements using Multiple Perfluorocarbon Tracers
In all passive monitoring system utilizing alpha -track detectors for radon and perfluorocarbon tracer (PFT) samplers for ventilation has been used to measure radon entry rates for 60 homes located within four separate areas of New York State (USA). Each home was divided into two or three zones so that multiple PFTs and multizone mass balance models could be used to compute zonal radon source rates. The whole house radon source rate for all 60 homes, averaged for a 2 to 7 week time period during the winter of 85-86, had a geometric mean of 4.94 Bq/s and an arithmetic mean of 10.0 Bq/s. Zonal mass balance equations applied to a tracer emitted in the soil outside 45 of the homes showed that, on average, 55% of the emitted tracer actually entered the houses. Diffusion alone cannot account for such a high value.
Abstract - Surficial Geology and Indoor Radon Studies in New York State
Several areas in New York State have been studied to investigate possible correlations between the surficial soil-bedrock geology and indoor radon. The soils and surficial bedrock were measured for radium concentration, emanating fraction, soil-gas radon concentration and soil permeability for gas flow. In addition, the geology of the areas were characterized regarding soil and rock type, depth of soil to bedrock and water table depth.
Eight areas in eight counties were investigated including three shale areas, two granite, two gravel and one sandy area. All areas except the sandy area were selected as potentially above average for indoor radon. Two of the shale areas contained above average concentrations of radium in the soil and bedrock formation in southeastern New York, varied from normal levels (~ 1 pCi/gm) to rocks containing up to 50 pCi/gm. The geometric means for the basement radon concentration measured during the heating season in these shale and granitic areas ranged from 2 to 6 pCi/L. Although the soil radium concentration in the gravelly areas were at normal levels (~ 1 pCi/gm), these areas were selected for their high permeability for gas flow. The indoor radon concentration measured in basements during the heating season for houses on gravel yielded geometric means of 20 and 9 pCi/L indicating the importance of soil-bedrock permeability for soil-gas infiltration. The homes measured in the sandy area, which is located in Long Island, had below average concentrations for both radium in the soil and indoor radon.
Abstract - Indoor Radon Measurements for Four Regions in New York State
Four areas have been selected for indoor radon measurements based on the surficial soil and bedrock geology. The availability of radon in the surficial soils and rock was characterized by measuring the concentration of radon in the soil gas and the radium concentration in the surficial soils and rock. Three areas were characterized as having above average radon availability and one below average. The areas selected as above average are located in Onandaga County, Erie County and Orange County. The below average area is located in Long Island. Fifteen homes from each area are being measured for indoor radon. For the fifteen homes in Onondaga County (above average area) the concentration of indoor radon measured using track etch detectors yielded geometric mean values of 3.4 pCi/L for the basement and 2.2 pCi/L for the first floor. Grab sample measurements of indoor air for the homes in Long Island (below average area) yielded a geometric mean of 0.8 pCi/L for the basements. Track etch measurements for all four areas will be completed by April 1986. Indoor radon concentrations will be correlated with soil radon availability factors.
Abstract - Identifying Areas with Potential for High Indoor Radon Results of Surficial Soil Measurements
Certain geographical areas are known to have homes with much higher radon concentrations than the average value. In order to identify and investigate soil gas as a major source, we are studying two regions in New York State. The Marcellus shale area near Syracuse was selected as a potentially high risk area for indoor radon concentrations above average values, whereas the Pine Bush area near Albany was selected as a low risk area. The soil Ra-226 concentration, soil gas Rn-222 content and the permeability of the soil for gas flow have been measured for surficial soils from both areas. The Marcellus shale is a middle Devonian marine shale, 15 to 60 feet thick with outcroppings located in a band across the state. The shale contains high concentrations of both organics and radionuclides. The Pine Bush area near Albany is a sandy glacial outwash deposit; similar deposits cover large areas of New York State.
Soils from the Marcellus shale area contain significantly greater concentrations of radium and soil-gas radon than do soils from the Pine Bush area. The soil gas measurements at each site were made at a depth of 2 to 5 feet by inserting a perforated pipe in the soil and withdrawing the gas. The Ra-226 concentration of three soil samples from the Marcellus shale area range from 1.2 to 2.5 pCi/g while in four samples from the Pine Bush they are 0.25 to 0.5 pCi/L and 4400 pCi/L for the Marcellus shale area and 125, 135, 140 and 150 pCi/L for four samples from the Pine Bush area. Rn-226 and Rn-222 concentrations measured at depths of 3 to 5 feet also show substantially greater concentrations for the Marcellus shale soils. The Rn-222 concentrations in soils gas near the foundation of four homes were found to be less than those from locations greater than 15 feet from the foundation, perhaps due to migration of soil gas into or around the foundation; this suggests caution in soil gas measurements near homes.