Soil gas (²²²Rn, CO₂, ⁴He) behaviour over a natural CO₂ accumulation, Montmiral area (Drôme, France): geographical, geological and temporal relationships

The south east basin of France shelters deep CO₂ reservoirs often studied with the aim of better constraining geological CO₂ storage operations. Here we present new soil gas data, completing an existing dataset (CO₂, ²²²Rn, ⁴He), together with mineralogical and physical characterisations of soil columns, in an attempt to better understand the spatial distribution of gas concentrations in the soils and to rule on the sealed character of the CO₂ reservoir at present time.Anomalous gas concentrations were found but did not appear to be clearly related to geological structures that may drain deep gases up to the surface, implying a dominant influence of near surface processes as indicated by carbon isotope ratios. Coarse grained, quartz-rich soils favoured the existence of high CO₂ concentrations. Fine grained clayey soils preferentially favoured the existence of ²²²Rn but not CO₂. Soil formations did not act as barriers preventing gas migrations in soils, either due to water content or due to mineralogical composition. No abundant leakage from the Montmiral reservoir can be highlighted by the measurements, even near the exploitation well. As good correlation between CO₂ and ²²²Rn concentrations still exist, it is suggested that ²²²Rn migration is also CO₂ dependent in non-leaking areas - diffusion dominated systems.     

Contribution of (222)Rn-bearing water to indoor radon and indoor air quality assessment in hot spring hotels of Guangdong, China

This study investigates the contribution of radon (²²²Rn)-bearing water to indoor ²²²Rn in thermal baths. The ²²²Rn concentrations in air were monitored in the bathroom and the bedroom. Particulate matter (PM, both PM₁₀ and PM_2.5) and carbon dioxide (CO₂) were also monitored with portable analyzers. The bathrooms were supplied with hot spring water containing 66-260 kBq m⁻³ of ²²²Rn. The results show that the spray of hot spring water from the bath spouts is the dominant mechanism by which ²²²Rn is released into the air of the bathroom, and then it diffuses into the bedroom. Average ²²²Rn level was 110-410% higher in the bedrooms and 510-1200% higher in the bathrooms compared to the corresponding average levels when there was no use of hot spring water. The indoor ²²²Rn levels were influenced by the ²²²Rn concentrations in the hot spring water and the bathing times. The average ²²²Rn transfer coefficients from water to air were 6.2 × 10⁻⁴-4.1 × 10⁻³. The 24-h average levels of CO₂ and PM₁₀ in the hotel rooms were 89% and 22% higher than the present Indoor Air Quality (IAQ) standard of China. The main particle pollutant in the hotel rooms was PM_2.5. Radon and PM₁₀ levels in some hotel rooms were at much higher concentrations than guideline levels, and thus the potential health risks to tourists and especially to the hotel workers should be of great concern, and measures should be taken to lower inhalation exposure to these air pollutants.     

Effect of moisture content on emanation at different grain size fractions - A pilot study on granitic esker sand sample

It is known that in soils and sediments moisture adsorbed on particle surfaces and in the pore system significantly affects the behaviour of recoiling radon (²²²Rn) atoms after decay of parent ²²⁶Ra, leading to increased ²²²Rn emanation. As a first step in an effort to characterize the ²²²Rn source term in mineralised sediments in the present study, complementing previous studies in the area, granitic esker sand samples were collected in order to test how moisture content affects ²²²Rn emanation at different grain size fractions. Emanation fractions measured for natural samples were compared with theoretical calculations. Six different grain size fractions were studied at 0%, 5% and 10% moisture contents relative to the mass of solids. In a further study necessary complementary information on the chemical and structural distribution of ²²⁶Ra was gained by selective leaching experiments. The results showed that ²²⁶Ra concentration increases from 50 Bq/kg at grain size 1-2 mm to 200 Bq/kg at grain size <0.063 mm. Respectively, the emanation factor increased from 0.12 to 0.30 at 5% moisture content. Both emanation factor and radium concentration increased significantly when grain size was below 0.125-0.250 mm. Above this fraction, the emanation fraction was approximately constant, 0.13 at 5% moisture content. In most of the grain size fractions, emanation reaches its maximum at 5% moisture content, being twice as high as in a dry sample. For the small particles (<0.063 mm) the ²²⁶Ra distribution is rather complex and depends on the mineral composition compared to larger particles wherein emanation from the internal pore system and the adjacent matrix is dominating over the contribution from external surface.     

Indoor and outdoor Radon concentration measurements in Sivas, Turkey, in comparison with geological setting

Indoor and soil gas Radon (²²²Rn) concentration measurements were accomplished in two stages in Sivas, a central eastern city in Turkey. In the first stage, CR-39 passive nuclear track detectors supplied by the Turkish Atomic Energy Authority (TAEA) were placed in the selected houses throughout Sivas centrum in two seasons; summer and winter. Before the setup of detectors, a detailed questionnaire form was distributed to the inhabitants of selected houses to investigate construction parameters and properties of the houses, and living conditions of inhabitants. Detectors were collected back two months later and analysed at TAEA laboratories to obtain indoor ²²²Rn gas concentration values. In the second stage, soil gas ²²²Rn measurements were performed using an alphameter near the selected houses for the indoor measurements. Although ²²²Rn concentrations in Sivas were quite low in relation with the allowable limits, they are higher than the average of Turkey. Indoor and soil gas ²²²Rn concentration distribution maps were prepared seperately and these maps were applied onto the surface geological map. In this way, both surveys were correlated with the each other and they were interpreted in comparison with the answers of questionnaire and the geological setting of the Sivas centrum and the vicinity.     

Radon emanation from NORM-contaminated pipe scale and soil at petroleum industry sites

Radon-222 emanation fractions were determined for barite scale deposits associated with petroleum production tubing and soil contaminated with naturally occurring radioactive material (NORM). Samples were analyzed for 226Ra concentration, the results of which were used to calculate the 222Rn emanation fraction for the sample. An important parameter determining the overall Rn activity flux from a solid medium, 222Rn emanation fraction represents the fraction of 222Rn produced that enters the interconnected pore space within a medium contaminated with 226Ra before the 222Rn undergoes radioactive decay. The primary objective of the study was to determine whether 222Rn emanation fractions from pipe scale and soil from petroleum production sites are similar to those of uranium mill tailings. Pipe scale samples were collected at four sites representing a wide geographical area, and consisted primarily of barite scale where Ra atoms have replaced a fraction of the Ba within the crystal lattice of the scale. Soil samples were collected at five sites, from areas exhibiting elevated surface gamma exposure rates indicating the presence of NORM. For comparison, 226Ra concentrations and 222Rn emanation fraction were also determined for uranium mill tailings samples provided from a site in Utah. Although 2226Ra concentrations from pipe scale samples were similar to those found in uranium mill tailings, 222Rn emanation fractions from scale were generally lower. Emanation fractions from each data set were statistically different from those of mill tailings (p < or = 0.01). The differences are probably due to physical differences between the two media and to the method by which the Ra is deposited in the material. Radon emanation from soils was extremely variable owing not only to differences in physical and chemical soil properties, but also to the means by which NORM has entered the soil. Although additional emanation measurements from other sites are needed, the data collected at these sites indicate that regulations intended to protect human health from 222Rn inhalation should consider the type and properties of the medium in which the NORM is contained, rather than relying strictly on concentrations of the parent 226Ra.     

The distribution of radon in tunnels with different geological characteristics in China

In China, as the economy is developing and the population is expanding, some underground buildings have been used as supermarkets, restaurants and entertainment places. Tunnels in mountains are one type of underground building, and the radon (²²²Rn) level in tunnels is an important issue. Radon levels in different type tunnels appear to differ, and relatively higher levels of ²²²Rn are associated with particular types of bedrock. The ²²²Rn levels in tunnels in five different geological characteristics were analyzed. Those built in granite had the highest ²²²Rn levels with a geometric mean (GM) of 280 Bq m⁻³, while those built in limestone (GM: 100 Bq m⁻³) and andesitic porphyry (GM: 96 Bq m⁻³) were lower. The sequence of ²²²Rn concentrations was: granite > tuff > quartz sandstone > limestone > andesitic porphyry, and the ²²²Rn in granite was statistically significantly higher than in limestone and andesitic porphyry. Tunnels built in granite, tuff, quartz sandstone, limestone tended to have higher ²²²Rn concentrations in summer than in winter, while the reverse tendency was true in andesitic porphyry tunnels. Only the difference in limestone was statistically significant.     

Indoor radon levels: Effects of energy-efficiency in homes

The expectation of elevated ²²²Rn levels in modern homes that have low air interchange rates with the outdoor air caused us to survey both solar and conventional homes in northeastern New York State. As a group, homes that are more airtight have three times the ²²²Rn levels of the conventional homes; they have other specific problems that are introduced or exaggerated by modern construction. For example, the highest two levels of radon in the solar homes give doses over 30 years that are known to produce lung cancer in 1% of uranium miners. Summer readings in more than one-half of the cases are different from winter ones by a factor of two or more, so that year-round measurements are necessary for precise dosimetry. The track-etching technique is ideally suited for such measurements. Radon emanation measurements on soils and sand demonstrate a considerable variety of release rates.     

Nationwide indoor 222Rn and 220Rn map for India: a review

Considering the role of radon in epidemiology, an attempt was made to make a nation-wide map of indoor ²²²Rn and ²²⁰Rn for India. More than 5000 measurements have been carried out in 1500 dwellings across the country comprising urban and nonurban locations. The solid state nuclear track detectors based twin cup ²²²Rn/²²⁰Rn discrimination dosimeters were deployed for the measurement of indoor ²²²Rn, ²²⁰Rn and their progeny levels. The geometric means of estimated annual inhalation dose rate due to indoor ²²²Rn, ²²⁰Rn and their progeny in the dwellings was 0.94 mSvy⁻¹ (geometric standard deviation 2.5). It was observed that the major contribution to the indoor inhalation dose was due to indoor ²²²Rn and its progeny. However, the contribution due to indoor ²²⁰Rn and its progeny was not trivial as it was found to be about 20% of the total indoor inhalation dose rates. The indoor ²²²Rn levels in dwellings was significantly different depending on the nature of walls and floorings.     

Possible effect of solar tides on radon signals

Large temporal variations of radon (²²²Rn) are often encountered in air in the geologic environment, at time scales from diurnal to annual. Interpretations as to the nature of these variations, unique to ²²²Rn, often invoke either above surface atmospheric variations, or the influence of subtle active geodynamic processes. So far the eventual geophysical drivers of the variation of ²²²Rn as well as its specific qualities enabling this temporal variation are not known. New insight on the temporal variation of ²²²Rn is gained by experimental simulation in confined air. Two short laboratory experiments, and one external experiment lasting over 3 years, were performed inside closed canisters and using natural and commercial ²²²Rn sources. Internal and external gamma and alpha detectors recorded variations of the radiation, up to around 20% of the equilibrium level. Radon signals of different time scale occurred with: a) periodic annual and semi-annual signals; b) non-periodic multi-day signals; c) periodic daily signals. Similar, related, inversely-related and dissimilar temporal patterns were manifested in the measured time series of the different sensors. Diurnal periodicity was dominated by the solar tide components S1, S2 and S3, exhibiting unlike relative amplitudes and different phases at the different sensors. A compound association occurs among the amplitudes and phases of the diurnal and seasonal periodicities of the daily ²²²Rn signal, linking the periodic phenomena to the rotation of earth around its axis and around the sun. ²²²Rn variation patterns in the frequency-time domain cannot be driven by the corresponding atmospheric variation patterns. These results, obtained under static and isolated conditions, are in disagreement with the expected radioactive equilibrium and its spatially uniform expression within and around the experimental volume. The external influence which drives the daily signals evolving from ²²²Rn inside the canister is non-atmospheric and seemed to be from a remote source and traversed a 5-cm thick lead shield. The similarities with observations on ²²²Rn signals from upper crustal levels imply that such an external influence, possibly as a component of solar irradiance, drives the ²²²Rn signals to a depth of at least 100 m. New combined prospects for the research are indicated in terms of the radioactive behavior of ²²²Rn in air and in terms of an above surface geophysical driver for this behavior.     

Inverse modeling of Asian Rn flux using surface air Rn concentration

When used with an atmospheric transport model, the ²²²Rn flux distribution estimated in our previous study using soil transport theory caused underestimation of atmospheric ²²²Rn concentrations as compared with measurements in East Asia. In this study, we applied a Bayesian synthesis inverse method to produce revised estimates of the annual ²²²Rn flux density in Asia by using atmospheric ²²²Rn concentrations measured at seven sites in East Asia. The Bayesian synthesis inverse method requires a prior estimate of the flux distribution and its uncertainties. The atmospheric transport model MM5/HIRAT and our previous estimate of the ²²²Rn flux distribution as the prior value were used to generate new flux estimates for the eastern half of the Eurasian continent dividing into 10 regions.The ²²²Rn flux densities estimated using the Bayesian inversion technique were generally higher than the prior flux densities. The area-weighted average ²²²Rn flux density for Asia was estimated to be 33.0 mBq m⁻² s⁻¹, which is substantially higher than the prior value (16.7 mBq m⁻² s⁻¹). The estimated ²²²Rn flux densities decrease with increasing latitude as follows: Southeast Asia (36.7 mBq m⁻² s⁻¹); East Asia (28.6 mBq m⁻² s⁻¹) including China, Korean Peninsula and Japan; and Siberia (14.1 mBq m⁻² s⁻¹). Increase of the newly estimated fluxes in Southeast Asia, China, Japan, and the southern part of Eastern Siberia from the prior ones contributed most significantly to improved agreement of the model-calculated concentrations with the atmospheric measurements. The sensitivity analysis of prior flux errors and effects of locally exhaled ²²²Rn showed that the estimated fluxes in Northern and Central China, Korea, Japan, and the southern part of Eastern Siberia were robust, but that in Central Asia had a large uncertainty.     

Po-210 and Pb-210 as atmospheric tracers and global atmospheric Pb-210 fallout: a review

Over the past ∼5 decades, the distribution of ²²²Rn and its progenies (mainly ²¹⁰Pb, ²¹⁰Bi and ²¹⁰Po) have provided a wealth of information as tracers to quantify several atmospheric processes that include: i) source tracking and transport time scales of air masses; ii) the stability and vertical movement of air masses iii) removal rate constants and residence times of aerosols; iv) chemical behavior of analog species; and v) washout ratios and deposition velocities of aerosols. Most of these applications require that the sources and sink terms of these nuclides are well characterized.Utility of ²¹⁰Pb, ²¹⁰Bi and ²¹⁰Po as atmospheric tracers requires that data on the ²²²Rn emanation rates is well documented. Due to low concentrations of ²²⁶Ra in surface waters, the ²²²Rn emanation rates from the continent is about two orders of magnitude higher than that of the ocean. This has led to distinctly higher ²¹⁰Pb concentrations in continental air masses compared to oceanic air masses. The highly varying concentrations of ²¹⁰Pb in air as well the depositional fluxes have yielded insight on the sources and transit times of aerosols. In an ideal enclosed air mass (closed system with respect to these nuclides), the residence times of aerosols obtained from the activity ratios of ²¹⁰Pb/²²²Rn, ²¹⁰Bi/²¹⁰Pb, and ²¹⁰Po/²¹⁰Pb are expected to agree with each other, but a large number of studies have indicated discordance between the residence times obtained from these three pairs. Recent results from the distribution of these nuclides in size-fractionated aerosols appear to yield consistent residence time in smaller-size aerosols, possibly suggesting that larger size aerosols are derived from resuspended dust. The residence times calculated from the ²¹⁰Pb/²²²Rn, ²¹⁰Bi/²¹⁰Pb, and ²¹⁰Po/²¹⁰Pb activity ratios published from 1970’s are compared to those data obtained in size-fractionated aerosols in this decade and possible reasons for the discordance is discussed with some key recommendations for future studies.The existing global atmospheric inventory data of ²¹⁰Pb is re-evaluated and a ‘global curve’ for the depositional fluxes of ²¹⁰Pb is established. A current global budget for atmospheric ²¹⁰Po and ²¹⁰Pb is also established. The relative importance of dry fallout of ²¹⁰Po and ²¹⁰Pb at different latitudes is evaluated. The global values for the deposition velocities of aerosols using ²¹⁰Po and ²¹⁰Pb are synthesized.     

Occupational exposure to radon and natural gamma radiation in the La Carolina, a former gold mine in San Luis Province, Argentina

Radon and gamma radiation level measurements were carried out inside the La Carolina mine, one of the oldest gold mining camps of southern South America, which is open for touristic visits nowadays. CR-39 track-etch detectors and thermoluminescent dosimeters of natural CaF₂ and LiF TLD-100 were exposed at 14 points along the mine tunnels in order to estimate the mean ²²²Rn concentration and the ambient dose equivalent during the summer season (November 2008 to February 2009). The values for the ²²²Rn concentration at each monitoring site ranged from 1.8 ± 0.1 kBq m⁻³ to 6.0 ± 0.5 kBq m⁻³, with a mean value of 4.8 kBq m⁻³, indicating that these measurements exceed in about three times the upper action level recommended by ICRP for workplaces. The correlations between radon and gamma radiation levels inside the mine were also investigated. Effective doses due to ²²²Rn and gamma rays inside the mine were determined, resulting in negligible values to tourists. Considering the effective dose to the mine tourist guides, values exceeding 20 mSv of internal contribution to the effective doses can be reached, depending on the number of working hours inside the mine.     

Natural radioactivity and radon exhalation in building materials used in Italian dwellings

Forty-two samples of building materials commonly used in Italian dwellings were surveyed for natural radioactivity. External (gamma), as defined and used by the European Commission, and internal (alpha) hazard indexes were calculated and radon specific exhalation rate and emanation fraction were measured. The accumulation method, by using the E-PERM electret ion chambers, was employed to determine specific exhalation rates of 222Rn. Several of the materials had hazard indexes that exceeded the European Commission limit values. However, it was evident that limit values for internal hazard indexes set based on Rn emanation should take into account the properties and use of the materials. For example, Rn emanation from basalt and glazed tiles was substantially lower than the Rn emanation from other materials with similar hazard indexes. Clearly there is need for improved guidelines and regulations in this area.     

Rn concentration in public secondary schools in Galicia (Spain)

In the framework of a ²²²Rn screening campaign that was carried out in 58 public secondary schools in Galicia (NW Spain), the largest radon-prone area in the Iberian Peninsula, a positive correlation between indoor ²²²Rn concentration and outdoor gamma exposure rate was obtained. A new approach to the data acquisition in screening surveys was tested, improving the performances of this type of study and gathering useful data for future remedial actions. Using short-period detectors (charcoal canisters) firstly, in order to detect places showing ²²²Rn concentrations over 400 Bq m⁻³, the number of locations to be measured with long-period detectors (etched track detectors) is reduced. In this screening campaign, 34% of the schools surveyed presented at least one site exceeding the 400 Bq m⁻³ recommended action level established by the EU, and 15% had at least one site with ²²²Rn values over 800 Bq m⁻³. The maximum value recorded was 2084 ± 63 Bq m⁻³. These results are discussed and compared with data obtained in schools of several countries with similar geology. Seven schools were also studied for seasonal variations of ²²²Rn activity concentration. The results were not conclusive, and no significant correlation between season and ²²²Rn concentration was established. Finally, a continuous ²²²Rn concentration monitor was placed in the secondary school exhibiting a mean value of the ²²²Rn concentration very close to 400 Bq m⁻³. Maximum ²²²Rn concentration values were found to occur at times when the school was unoccupied.     

Isotope tracing of submarine groundwater discharge offshore Ubatuba, Brazil: results of the IAEA–UNESCO SGD project

Results of groundwater and seawater analyses for radioactive (³H, ²²²Rn, ²²³Ra, ²²⁴Ra, ²²⁶Ra, and ²²⁸Ra) and stable (D and ¹⁸O) isotopes are presented together with in situ spatial mapping and time series ²²²Rn measurements in seawater, direct seepage measurements using manual and automated seepage meters, pore water investigations using different tracers and piezometric techniques, and geoelectric surveys probing the coast. This study represents first time that such a new complex arsenal of radioactive and non-radioactive tracer techniques and geophysical methods have been used for simultaneous submarine groundwater discharge (SGD) investigations. Large fluctuations of SGD fluxes were observed at sites situated only a few meters apart (from 0 cm d⁻¹ to 360 cm d⁻¹; the unit represents cm³/cm²/day), as well as during a few hours (from 0 cm d⁻¹ to 110 cm d⁻¹), strongly depending on the tidal fluctuations. The average SGD flux estimated from continuous ²²²Rn measurements is 17 ± 10 cm d⁻¹. Integrated coastal SGD flux estimated for the Ubatuba coast using radium isotopes is about 7 × 10³ m³ d⁻¹ per km of the coast. The isotopic composition (δD and δ¹⁸O) of submarine waters was characterised by significant variability and heavy isotope enrichment, indicating that the contribution of groundwater in submarine waters varied from a small percentage to 20%. However, this contribution with increasing offshore distance became negligible. Automated seepage meters and time series measurements of ²²²Rn activity concentration showed a negative correlation between the SGD rates and tidal stage. This is likely caused by sea level changes as tidal effects induce variations of hydraulic gradients. The geoelectric probing and piezometric measurements contributed to better understanding of the spatial distribution of different water masses present along the coast. The radium isotope data showed scattered distributions with offshore distance, which imply that seawater in a complex coast with many small bays and islands was influenced by local currents and groundwater/seawater mixing. This has also been confirmed by a relatively short residence time of 1–2 weeks for water within 25 km offshore, as obtained by short-lived radium isotopes. The irregular distribution of SGD seen at Ubatuba is a characteristic of fractured rock aquifers, fed by coastal groundwater and recirculated seawater with small admixtures of groundwater, which is of potential environmental concern and has implications on the management of freshwater resources in the region.     

A Monte Carlo study of radon detection in cylindrical diffusion chambers

The functioning of radon diffusion chambers was studied using the Monte Carlo code RAMMX developed here. The alpha particles from radon are assumed randomly produced in the volume of the cylinder, and those from the progeny are assumed to originate randomly at the cylindrical surface. The energy spectrum, the distribution of incident angles, and the distribution of path lengths of the alpha particles on the detector were obtained. These quantities vary depending on input parameters such as initial alpha particle energy, radius and depth of the diffusion chamber, detector size and atmospheric pressure. The calculated energy spectrum for both ²²²Rn and ²²⁰Rn was compared with experiment, permitting the identification of each peak and its origin, and a better understanding of radon monitoring. Three aspects not considered in previous calculations are progeny alphas coming from surfaces of the monitor, taking into account the atmospheric pressure, and including the isotope ²²⁰Rn.     

Development of an energy discriminate CR-39(®) nuclear track etch dosimeter for Radon-220 gas measurements

An energy discriminate CR-39^® nuclear track etch dosimeter for use in a ²²⁰Rn and ²²²Rn gas monitor has been developed and experimentally assessed. It utilises a thin film of Mylar^® C to attenuate the alpha particle energies to allow only the damage tracks created by the 8.785 MeV alpha particles emitted from ²¹²Po of the ²³²Th decay chain to be registered in the CR-39^® plaque, allowing for the direct measurement of ²²⁰Rn gas concentrations. The dosimeter was developed through a combination of experimental investigations and theoretical simulations using the Monte Carlo ion transport modelling program Stopping and Range of Ions in Materials (SRIM 2008). A film thickness of 54 μm has been shown to attenuate all alpha energies less then 7.7 MeV.     

A simple and rapid method for analyzing radon in coastal and ground waters using a radon-in-air monitor

We have developed a simple and portable technique for measuring moderately high levels of 222Rn (t1/2=3.8d) in natural waters such as coastal water, groundwater, and river water. The water sample is carefully collected in a glass bottle, and the sample bottle is connected to a radon-in-air monitor in a closed air-loop mode. By purging air through the sample, radon is emanated from the water until a chemical equilibration is obtained between the two phases. The radon in the air loop is determined using the radon-in-air monitor. Then, the radon in water is calculated by a radon-partitioning factor between water and air for a measured water temperature. This technique is especially convenient for determination of 222Rn in natural waters on field sites, since it eliminates the preparation of He gas, cold traps, and alpha-scintillation cells and counter, which are required for traditional radon emanation methods.     

Modeling the Pb activity concentration in the lower atmosphere

A worldwide radionuclide network of 80 stations, part of the International Monitoring System, is being setup to monitor compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT). The radioactivity sampled at these stations is primarily ²²⁰Rn progenies affecting the detection capability. A model linking the ²²⁰Rn emanation with the sampled ²¹²Pb activity was developed and is presented here. The model and the performed measurements show that the variation of the sampled ²¹²Pb activity can be fully explained by the variation of the local ²²⁰Rn activity concentration.     

Occupational dosimetric assessment (inhalation pathway) from the application of phosphogypsum in agriculture in South West Spain

Phosphogypsum (PG) has been traditionally applied as Ca-amendment in saline marsh soils in SW Spain, where available PG has 710 ± 40 Bq kg⁻¹ of ²²⁶Ra. This work assesses the potential radiological risk for farmers through ²²²Rn exhalation from PG-amended soils and by inhalation of PG-dust during its application. A three-year field experiment was conducted in a commercial farm involving two treatments: control and 25 t PG ha⁻¹ with three replicates (each 0.5 ha plots). The ²²²Rn exhalation rate was positively correlated with potential evapotranspiration, which explained 67% of the variability. Statistically significant differences between the control and PG treatments were not found for ²²²Rn exhalation rates, and mean values were within the lowest quartile of the typical range for ²²²Rn exhalation from soils. Airborne dust samples were collected during the application of PG and sugar-beet sludge amendments. The highest PG-attributable ²²⁶Ra concentration in the dust samples was 3.3 × 10² μBq m⁻³, implying negligible dose increment for exposed workers.