Radiation Protection Legislation and Sustainable Development of a Rural Green Tuff Village of Ischia Island

Abstract

Radiological risk affects the quality of the environment in buildings since population and workers can be potentially exposed to high levels of radiation. Radon gas emanating from both subsoil and building materials represents the most important source of radiation exposure for people. This study investigates the sustainability concept of a small rural village of Ischia Island, named Ciglio, in relation to radiation protection legislation concerning the radiological risk for workers. Radon activity concentration was measured in typical green-tuff dwellings and in water samples collected from a local waterfall E-Perm devices. Moreover, for green tuff as building material, the radon emanation coefficient was calculated by gamma spectroscopy. The results highlight the importance of performing environmental radon monitoring and investigating the radon content of building materials, especially in geographical areas characterized by traditional use of typical stones for constructions. In conclusion, the sustainable development of rural buildings is possible if the radiological risk for inhabitants and workers is assessed in line with the national radiation protection legislation.

1. Introduction and Literature Review

In recent years the issue of sustainability has aroused an increasing interest in different fields of study as it involves a wide range of human activities, such as policy, economy, traditional culture and civil architecture [1,2,3,4,5]. Sustainability is a multidimensional concept with various perspectives in the natural, historical, environmental and cultural texture of communities in both cities and rural areas.

In particular, traditional rural areas and one-off built structures represent an important imprint of our cultural heritage; preserving the local architectural heritage and transferring it to future generations has a great impact on sustainability.

Despite widely available literature on the concept of sustainability [4,6,7,8,9], definition of “sustainable building” are still unclear and biased [10]. Generally, “design and construction of sustainable buildings” usually refers to the energy efficiency, renewable materials and reduction of emissions, wastes and pollutants in buildings, neglecting the relations between built, natural and social systems [11]. Indeed, sustainable development of villages and their buildings have a significant influence on the economy, on resource demand and consumption, building design and construction, planning and transport, and communication [4].

Many works report studies on the relation between the traditional Italian rural landscape and the individual and social dimension, detecting the variety and richness of rural buildings that represent the cultural identity and economy of the local communities [12,13,14,15]. In this context, management strategies and cultural heritage policies are fundamental to implement the functional use of the rural spaces while preserving the landscape at the same time [13].

The sustainability approach in the building sector has led the construction industry to consider economic, environmental and social aspects rather than time, cost and quality as indicators of the level of efficiency [7]. In the available literature, recent studies report Italian regional cases studies on the building typologies and the sustainable development of rural settlements. The reuse of the locally available construction materials and the enhancement of traditional rural buildings (TRBs) have been a strategic solution in support of the sustainable policy [8,16].

Over the years, various European and national programs, supported by financial projects, have promoted the reuse of TRBs aiming at preserving, developing and supporting local identities and natural resources [17,18,19]. The rehabilitation of TRBs can be an opportunity for the local communities to implement different tourist attractiveness and activities: accommodation facilities, meeting places, conference halls, restaurants, hotels, museums, residential centers and much more. The phenomenon of rural tourism is becoming increasingly popular since visitors rediscover historical traditions, memories and social identities, at the same time as they enjoy the natural landscape [17,20,21]. It is clear that, as consequence of the sustainable development of rural areas, the presence of people (inhabitants, visitors and workers) involved in receptive activities or guided tours, is intensified. Consequently, sustainable planning of social, cultural and economic activities must be integrated with an appropriate planning for the safety of occupants, workers and public.

The knowledge of the territory and surrounding environment, construction techniques and materials, plays a key role in the implementation of adequate security and protection conditions.

The history of the Ischia Island (southern Italy) is mainly characterized by the volcanism activity that influenced the geological and morphological structure of the island and surrounding area. The island represents the emerged portion of a wide volcanic field including both Somma-Vesuvius and the Phlegrean Fields. As consequence, the soil composition of Ischia has peculiar mineralogical, chemical and textural characteristics, which are then found in the building materials used for constructions. In particular, a small rural village near Serrara Fontana Ischia, named Ciglio, is a touristic attraction thanks to its green landscape and ancient constructions.

Typical buildings of Ciglio were built with green tuff, a natural stone widely spread on the island after Mount Epomeo eruption [22]. About 55000 years ago, there was a strong activity in a large magma chamber located under the island of Ischia. The deposits of these mighty eruptions are known as the “Monte Epomeo Green Tuff”. The grey-green color was probably caused by the prolonged contact of the rock with seawater. The chemical composition of green tuff consists primarily of phillipsite, pyrogenic K-feldspar and clay minerals. Mineralogical, chemical and textural information on green tuff as well as details on geological history of the Ciglio area are available in ref. [23].

The abundance of this material in this place has influenced the architecture and construction techniques. There are in fact two peculiar techniques: sculpting directly into the rock to obtain a habitable space or extracting blocks of tuff from the original sites and building above the street level. Buildings built with a combination of the two techniques can also be observed. Today these traditional buildings are intended for residential or tourist accommodation.

2. Aim of the Study, Radon Issue and Legislative Background

The main topic of this study is the contribution to environmental radioactivity from the most abundant component of natural origin: radon gas. We have focused on the issue of radiation protection for the public and workers, analyzing it both based on Italian legislation and European directive [24,25]. Radon (²²²Rn) is a radioactive gas (half-life of 3.8 days) produced by the radium-226 (²²⁶Ra) in the uranium-238 (²³⁸U) decay chain. It is a naturally occurring element present in soil, rocks and earth’s crust. Short-living alpha emitters descendants of ²²²Rn (²¹⁸Po, ²¹⁴Pb, ²¹⁴Bi and ²¹⁴Po) with a half-life of a few seconds are responsible for a natural source of internal exposure. The lungs are affected when aerosols carrying these radioactive decay products from the radon gas are inhaled. Once deposited on the surface of the lungs, the radioelements emit alpha rays which can penetrate deep enough to reach the cells of the bronchioles and lead to the DNA damage that underlies mutations which could cause cancer [26]. In 1998, the International Agency for Research on Cancer (IARC) classified radon and its decay products as carcinogens of group 1 for humans [27] and in 2009 the Worth Health Organization (WHO) identified in radon the second highest cause of lung cancer, after smoking [28]. The risk of radon exposure depends on the radon concentration in homes and workplaces (radon indoor) where people spend most of their time [29,30]. Radon enters in buildings mainly through the porous basement foundations but also as radioactive content in natural stones used as building materials [31] and especially accumulates on floor levels. Since radon mobility is influenced by the rock porosity, radon concentration in tuff-constructed buildings is potentially much higher than constructions built with materials characterized by a more compact matrix.

As it is well known, the full amount of radon produced in the matrix (soil and building materials) does not have the potential to reach the environment. In fact, only a fraction of radon atoms acquires the minimum kinetic energy to leave the grain of the material where it has been generated, so as to reach the empty space in the solid matrix. This process is named emanation and the emanated radon fraction is the emanation coefficient.

In addition to inhalation, another source of incorporation of radionuclides, and therefore of internal radiation, is the ingestion of these through drinking water which contains a level of concentration of radon enough to increase the probability of biological damage. It has been estimated that a daily consumption of 2 L of water with a radon concentration of 100 Bq/L can provide an annual effective dose of about 0.1 mSv [32]. This value of radon activity concentration is defined “parameter value” (or “attention value”), established by the current Italian Legislative Decree 28/2016 [32], which implements the Council Directive 2013/51/EURATOM regulating the radiological control of water intended for human use. If the concentration of radon gas activity exceeds the parameter value, it is mandatory to calculate the so-called indicative dose to ensure consumer safety.

Concerning the health protection of people against the risk deriving from ionizing radiation, in particular from inhalation of radon gas, the Italian legislation is represented by the Legislative Decree 241/00 (in force at the time of measurement), that establishes an action level of mean annual radon concentration equal to 500 Bq/m³ and an annual effective dose of 3 mSv/year in the workplaces. The decree identifies radon risk areas: underground workplaces such as tunnels, subways, catacombs, caves and areas with specific characteristics where are implemented activities involving workers and, eventually, the public as stated in the Article 10-bis, comma 1, letter a of the Legislative Decree 241/00, [24]. On the other hand, the letter b of the same Article indicates the “work activities during which the workers and possibly people from the public are exposed to decay products of radon or thoron, or a gamma radiation or any other exposure in places of work other than those referred to in letter a) in areas well identified or with specific characteristics”. Ischia Island, due to its volcanic origin, has its own specific characteristics. Recently, in August 2020, Italy implemented Directive 2013/59/EURATOM [25] with Legislative Decree 101/2020, which repeals Legislative Decree 241/00. The greatest social and managerial impact of Legislative Decree 101/2020 lies in the updating and expansion of the recommendations for the protection of health in all closed environments, including workplaces and homes, in a monitoring program of radiation. In particular, the Legislative Decree 101/2020 at Article 12 comma 1 establishes the reference level of the radon concentration equal to 300 Bq/m³ both in buildings intended for residential use and in workplaces, and raises the limit of the effective average annual dose up to 6 mSv. In this framework, our study was performed before the emanation of the current legislation; consequently, the results are presented and interpreted according to the Legislative Decree 241/2000.

The aim of this work was to strengthen the concept of sustainability by introducing the variable of safe work and public employment. About territorial examination, many works of literature have reported measurements of the activity indoor radon concentration in Italian homes [33,34], underground workplaces [35,36], schools [37,38,39,40] and tourist attraction sites on the island of Ischia such as thermal spas centers [41]. However, none of them investigate the impact of the radiation exposure issue on sustainable environmental design and development. In this work, we investigated some aspects of the exposure risk to radon deriving from the radon content in different material and environments (indoor air, water and building materials) in the village of Ciglio on Ischia Island. One church and one dwelling were selected for the measurements of radon indoor activity concentration. Six samples of water were collected in loco from an ancient waterfall to measure radon content. The average annual effective dose for the radioprotection of workers was estimated according to Decree 241/00 only when the concentration of radon activity exceeded the reference value. Finally, a preliminary radiological characterization of green tuff was performed measuring the emanation coefficient of five samples extracted from a site near the church.

3. Materials and Methods

3.1. Traditional Rural Buildings Selected for Radon Concentration Measurements

Ciglio is a small rupestrian village of seventeenth century with a great landscape impact and famous for its “stone houses” carved into the rock, once used as a dwelling and today integrated with modern houses built along the road that climbs to the slopes of Mount Epomeo. The south-western side of the Ischia Island, including Ciglio, is pervaded by a large amount of green tuff, so much so that native construction techniques based on the use of this natural stone have been encouraged in this area. The buildings were used to support the economic and sustenance activities of the pre-industrial era, based on agriculture and winemaking. Often these buildings were equipped with a single opening and without windows or with a little hole above the access door. The stone houses served different purposes, both for the preservation of the products and as a shelter for the farmers and breeders, who spent much time on the mountain. These buildings date back to the 14th–15th centuries and their use has been continuous for about 500 years. To date, even if most dwellings are abandoned, many of them have been converted in warehouses, garages, stables, and accommodations as well. Furthermore, the stone houses constitute a tourist attraction together with some rock constructions of religious nature. For our investigation and radiological characterization, two TRB sites were selected as representative of the two construction techniques in use: a house, obtained by digging directly into a rock boulder, and a church built with extracted tuff blocks (Figure 1a,b). In addition, six samples for the radiological water analysis were collected, from a tap directly connected to a cave in which a small waterfall flows from the overlooking Mount Epomeo and from inside the church.

Finally, for the radon emanation study from typical stones, tuff bricks were collected, emulating the same approach as the builders in the area who used the material found in the surrounding areas.

3.2. Measurement of Radon Activity Concentration in Air

Radon concentration measurements in indoor air were carried out using a conventional electret passive environmental radon monitor (E-Perm) electret ion chamber (EIC) system manufactured by Rad. Elec. Inc., (Frederick, MD, USA) [42,43,44,45].

The measurements were performed in the radioactivity laboratory certified UNI EN ISO 9001: 2015 for measures of concentration of activity of radon gas [46].

E-Perm devices were used in Long–Long Term (LLT) configuration: chamber Long Term and low sensitivity electret Long Term [43].

The charge loss of the electret was measured using an electrometer (Rad. Elec. Inc. Mod. 6383-01, Frederick, MD, USA).

The picture in Figure 2 shows the electrometer and Long and Short E-Perm chambers.

Since E-Perm are sensitive to gamma radiation, radon concentration measure requires corrections for cosmic and terrestrial radiation background. The method has been already described in detail elsewhere [41]. The gamma dose rate was measured at each site using a portable proportional counter (Berthold Technologies, Germany). The range of gamma dose rate across the monitored sites varied from a minimum of 0.27 ± 0.01 µGy h⁻¹ to a maximum of 0.31 ± 0.02 µGy h⁻¹.

The radon concentration was calculated applying the appropriate calibration factor and the exposure time, according to Equations (1) and (2) given by Kotrappa et al. [44]:

$$C_{Rn}=\left[\frac{\left(V_i-V_f\right)}{CF\times T}- G_{\gamma }{C}_1\right]\times 37$$

(1)

$$CF=C_2+C_{3 }\left(V_i-V_f\right)/2$$

(2)

where:

• V_i and V_f: electret voltage readings before and after exposure respectively;
• T: exposure time in days;
• G_γ: gamma dose rate in µR h⁻¹;
• C₁ = 0.59, C₂ = 0.02383, C₃ = 0.0000112: constants given by the manufacturer depending on configuration and volume of the E-Perm chamber.

The measurement was carried out between November 2019 and July 2020.

The E-Perm devices were exposed in several places of the selected buildings in order to have a significant distribution of measured values of radon concentration. In particular, three measurement points were chosen in the San Ciro church and one in the living room of the dwelling, where occupants spent most of their time. The planimetry of the buildings with the scheme of exposure of the E-Perm systems is reported in Figure 3. The E-Perm devices were exposed away from windows and doors, at about 1.5 m above the floor and 0.5 m from the wall. The exposure period was long (232 days).

3.3. Measurement of Radon Activity Concentration in Water

As for indoor radon measurement, E-Perm EIC system were used to perform radon activity concentration measurement in water. Six water samples were collected directly from the tap with bottles of 140 mL each, taking care to fill them slowly in order to avoid radon lack. After transport to the laboratory, within about 24 h of collection, each 140 mL bottle was opened and immediately placed in a 4 L glass jar with a suspended E-Perm chamber in Short-Short Term configuration (SST) (Figure 4).

The jar containing the electret and water sample was sealed (airtight) for 94 h to allow radon to reach equilibrium with its daughters. To determine the radon concentration in the water sample, the reading of the voltage electret discharge was used with a formula (3) provided by the manufacturer [42]:

$$C_{Rn}\left(water\right)=C_{Rn}+B_{1 }+B_2+B_{3 }$$

(3)

where:

• C_Rn: radon concentration measured in the air inside the jar by Equations (1) and (2) where C₁ = 0.097, C₂ = 1.670, C₃ = 0.0005742;
• B₁: period between the collection of the water sample and the start of the measurement;
• B₂: period from the time of inserting the sampling bottle into the jar until the E-Perm is removed;
• B₃: ratio between the volume of the jar and the water sample.

A more detailed description of the formula is available in ref. [36].

3.4. Calculation of Annual Effective Radon Dose

The annual effective dose (H) due to exposure of radon progeny in air was calculated from the experimentally determined value of radon concentration using expression (4):

$$\mathrm{H}\left({\mathrm{mSv}\mathrm{y}}^{-1}\right)=C_{Rn}\times \mathrm{O}\times \mathrm{D}$$

(4)

where:

• C_Rn: indoor radon concentration (Bq m⁻³);
• O: occupancy factor (2000 h y⁻¹ at work);
• D: dose coefficient.

Italian legislation [24] suggests using the conventional dose coefficient of 3 × 10⁻⁶ mSv per Bq h m⁻³ (Annex I-bis, comma 6).

D expressed in terms of ²²²Rn gas exposure includes the equilibrium factor F, representing the equilibrium between radon gas and its short-lived decay products. The value of the equilibrium factor is between 0.1 and 0.9 and depends on many environmental variables [47], however the environmental conditions of the buildings were standard and for this reason in this study we adopted the standard hypothesis of F = 0.4 as the Italian legislation established for most indoor situations.

3.5. Emanation Coefficient

3.5.1. Sample Preparation

Before analysis, each sample was processed according to the protocol UNI EN ISO 18589-2:2015 (Measurement of radioactivity environment—Soil guidance for the selection of the sampling strategy, sampling and pre-treatment of samples) in order to obtain a homogenous and uniform matrix. The samples were prepared reducing bricks to powder by grinding with the Planetary Ball Mills (PM 100 Retsch, Thermo Fischer Scientific, Milan, Italy). The planetary is able to reduce the input material to a fine-grained matrix down to less than 1 micron. The obtained powder was sieved and dried in an oven (DIGITRONIC Selecta 2005141; JP Selecta, Barcelona, Spain) at 105 °C for 2 h, thus it was homogenized according to the measurement techniques [10]. The final product was weighted and sealed in a Marinelli Beaker for 4 weeks to allow ²²⁶Ra and gamma daughters to reach secular equilibrium. The number of the analyzed samples was enough to ensure statistical significance.

3.5.2. Emanation Coefficient Measurement

The emanation coefficient of ²²²Rn in samples of green tuff was obtained by the ratio between the activity concentration of emanated radon fraction and the total radon concentration in equilibrium with ²²⁶Ra in the same material. The first one was measured in an electrostatic collection chamber (see Figure 5a); the total activity concentration of ²²⁶Ra in the materials was measured by gamma ray spectroscopy on another sample of the same material put in a Marinelli beaker. The measured emanation coefficient was obviously referred to the characteristic of the material.

The measurement of the radon concentration released in air was measured by putting the sample into a box characterized by a diameter of 8 cm and height equal to 2.5 cm included in a chamber of 0.765 L. A positive high voltage applied between chamber wall and alpha detector produced the transport of ionized daughter of radon (²¹⁸Po) and Thoron (²¹⁶Po) on the detector surface. Therefore, the alpha particles emitted can reach the depleted zone of the diode without energy loss and in these conditions a high-resolution alpha particles spectrometry can be performed, despite the presence of air in the chamber.

The energy performance of the high-resolution gamma spectrometry system, consisting of a coaxial High Purity 129 Germanium (HPGe ORTEC^®) detector, model GMX-45P4ST (see Figure 5b), was defined by the relative efficiency equal to 48% and energy resolution, measured as full width at half maximum (FWHM), equal to 2.16 keV at 1.33 MeV. The detector was equipped with a beryllium window that ensured a good sensitivity also at energy lower than 100 keV. The minimum detectable activity (MDA) of the system was estimated with 95% confidence level. The detector was shielded from external background by 7.5 cm lead circular wall.

The spectra were acquired by Ortec DSPEC-LF unit plus MCA Emulator software and analyzed with GammaVision Spectrum Analysis Software.

The alpha lines for the measurement of the exhalated radon fraction was that at 7687 keV of ²¹⁴Po and that at 6030 keV of ²¹⁸Po. The line of ²¹⁸Po interfered with the line at 6090 keV of ²¹²Bi (Thorium series) so to take this contribution into account, it was subtracted from peak due to ²¹⁴Po and ²¹⁴Bi, half of the intensity of the single peak of ²¹²Po at 8784 keV of the same series.

The gamma measurements were carried out on a sample of the same grain size characteristic in 1 L Marinelli Beaker. The gamma rays used for determining the total radon content of the green tuff were 295 keV, 352 keV (²¹⁴Bi) and 609 keV (²¹⁴Pb).

Alpha spectra data were saved in different files coming from the alpha detector, with related files included in a single directory.

4. Results

The radon activity concentrations for each measurement point in the church and dwelling are reported in

Table 1. Radon concentration in air for each measurement point in the church and dwelling.

Measurement Point	Activity Radon Concentration (Bq/m3)
	church	dwelling
#1	210 ± 20	210 ± 20
#2	120 ± 20
#3	540 ± 40

.

The mean radon concentration in the six water samples was 12 ± 1 Bq/L.

The measurement of emanation coefficient in the six samples of green-tuff stones provided a mean value of 8 ± 2%.

5. Discussion

The results show that according to the national legislation for the workplace [24], in the church one measurement point (#3 see Table 1), corresponding to the sacristy, exceeded the action level of 500 Bq/m³. Obviously, the value of radon concentration in the sacristy also exceeded the reference level of 300 Bq/m³ recommended by the European Commission in Directive 2013/59/EURATOM [25] and thus also the recent Italian legislation [48]. In the other measurement points of the church, the radon concentration was lower than the reference value.

The result is very interesting for the consequence concerning the eventual presence of people in the building. Italian regulation requires implementing adequate remedial actions (i.e., architectural remediation, building configuration, ventilation), if the mean annual effective dose exceeds the level of 3 mSv/y. For the conventional occupancy time of 2000 h/y in the sacristy, the mean annual effective dose results in 3.3 mSv/y. In this case, the sacristan and the priest spend only 150 h/y, as they stated, corresponding to a mean annual effective dose of 0.2 mSv/y.

The study was performed independently on the intended use of the building since the dwelling and the San Ciro church are representative of local constructive techniques (carved directly into the rock and built with extracted tuff, respectively) used to construct other buildings potentially intended for activities involving workers and opened to the public.

The value of radon concentration measured in the dwelling meets the requirements of the Italian regulation [48], with results below 300 Bq/m³, and it is consistent with the results reported in a previous work [49], investigating the radon concentration in several dwellings of Ischia Island. However, we can assert that the occupants of this area should frequently open windows and doors in order to reduce the radon concentration and consequently the effective annual dose, through natural ventilation, since the value of radon activity concentration in the dwelling resulted much higher than the regional mean 95 ± 3 Bq/m³ reported in ref. [33]. In addition, radon mitigation should aim to achieve the WHO recommended goal of lowering the level of radon concentration in homes below 100 Bq/m³ in order to limit the risk to individuals [28]. The effectiveness of natural ventilation on reducing radon indoor level has been already evaluated in some dwelling of Puglia region (southern Italy) [50].

The radon activity concentration found in water samples was within the limit stated by the Italian regulation (<100 Bq/L) [32]. Consequently, neither further screening of radioactivity content nor any risk assessments and corrective actions are mandatory. The safety of the water flow was assessed for eventually ingestion; it is interesting to note that the presence of the water flow could have an effect of the indoor radon concentration in the surrounding environment. In fact, the high value of radon concentration in the sacristy with respect to the other rooms could be attributed to two causes: the presence of water flow which releases the radon gas and the tuff-walls without plaster. We can speculate that since radon has solubility in water depending on the temperature and other conditions of the microenvironment, a percentage of radon reaches the surface inside the sacristy. In a future work, we are planning to estimate the contribution of the radon content in water to radon accumulation in the surrounding environment, though further measurements will be designed ad hoc. On the other hand, in the sacristy, the radon emanated from the green tuff could greatly contribute to the indoor accumulation. In the other rooms, the plaster probably acts as a screen for alpha particles, which do not reach the environment.

The emanation coefficient measured from the green-tuff samples was comparable with the values reported in ref. [51] for volcanic materials used as building material in Campania region, including tuff from Monte Epomeo on Ischia Island. In addition, the result obtained was comparable with those contained in the ISTISAN report 17/36 [52] for volcanic tuff. This report is an extensive database of emanation rate measured in approximately 1500 samples of building materials or their components used in the construction industry in most European Countries. The estimation of radon emanation rate from building materials is crucial to assess the radon exposure hazard since the dominant contributor to indoor radon is the emanation from soil and fractured bedrock close to the surface. In this context, recent studies deal with radon exposure risk and lung cancer incidence in south-eastern Italy [53,54], together with radiological characterization of typical stones used for constructions [31].

The findings of the study remark the importance to monitor the radon concentration in traditional buildings that potentially could come into programs of promotion of multifunctional use of TRBs. The Ciglio area is representative of the entire Italian peninsula, which increasingly promotes sites with peculiar architectural and geological characteristics. Therefore, the radiological surveillance of the environments, indicating the level of exposure risk, seems to be a priority before taking into account the development of any area leading to high occupancy time for workers and the general population. Similar to Ciglio, in these regions, local geology led to a widespread use of building materials potentially rich in uranium and radioactivity.

The obtained results provide information useful to design a development planning of rural and touristic activities, in line with the sustainability concept in areas where the enhancement of local traditions was supported by national and local policy. In this regard, since 1999, Ciglio is included in the Landscape Plan “Ischia Island” [55] having the double aim of blocking the processes of degradation and to develop the enormous urban, landscape and environmental heritage, already present. Inhabitants, sensible to the traditional value of the local heritage, have a primary role in preserving the characteristics of the original landscape in combination with a concrete sense of innovation and renewal. In this perspective, the results of the study ensure workers, tourists and the local community of Ciglio can be fully experienced in health-safety if the radioprotection isn’t neglected.

6. Conclusions

For the first time the sustainability concept has been evaluated in relation to the radioprotection issue in the peculiar area of Ciglio village, on Ischia Island.

The radon concentration was measured in two typical rural buildings and in water samples collected from an ancient waterfall. When mandatory, the evaluation of mean effective dose per year was calculated for workers in accordance with the national radiation protection legislation. The emanation coefficient of green tuff was also carried out.

The obtained values of the radon activity concentration measurements resulted below the limits stated by the radiation protection legislation (300 Bq/m³) except in one room of the church where the individual occupancy time is such that the mean annual effective dose is within the reference value of 3 mSv/year. Consequently, according to national regulation, no remedial action is necessary in order to reduce the radon activity concentration in the analyzed environments.

Although in the analyzed samples (indoor air, water and green tuff) the radiological parameters resulted to be safe, study highlighted the need to evaluate the impact of radon gas on individual radiation exposure. The high radon activity concentration found in the dwellings 210 ± 20 Bq/m³, much higher than the national mean value raises the issue of the radiation exposure of general people in homes. The calculation of the emanation coefficient of typical stones marks the importance to assess the relation between the building materials and geological structures on radon activity concentration in order to implement the sustainable planning of social and economic activities in the Ciglio rural area. This study presents a perspective in which the valorization of rural landscape, involving both natural and cultural dimensions, also includes the radioprotection concept, which is essential to guarantee occupational safety.