**6. Conclusions**

The infrastructure of the *Británica* warehouses of Alicante is a very important industrial architectural element in the history of Spain, although it is unknown to almost all the inhabitants of the city. The former fuel refinery is located in the Serra Grossa and served much of the country until 1966.

As an element for the future accommodation of people, it is necessary to carry out an air quality study with radon gas as an indicator. The results obtained in the installation show a high average amount of radon gas inside, which is explained by the limited air movement and its contact with the ground. The values in the eleven measurement zones varied between 1203.62 and 2413.48 Bq/m3, quadrupling the threshold of 300 Bq/m<sup>3</sup> in the most favorable case, and establishing values for which corrective ventilation measures must be taken.

The old *Británica* warehouses exhibit radon values much higher than those estimated for constructions in Alicante, if we consider the Marna map, where the area of the Levante is considered low risk. When this area is rehabilitated as recently proposed, the observation of high amounts of radon gas inside must be addressed and solutions adopted. These must be oriented to better renew the interior air by means of mechanical processes to avoid making more openings in the mountain that would distort the landscape and weaken the structure. It is for this reason that the current conditions should not be considered suitable for accommodating people until remodeling projects that include adequate ventilation of the installation have been carried out.

**Author Contributions:** The work presented here was developed in collaboration among all the authors. All of the authors have contributed to, seen and approved the manuscript.

**Acknowledgments:** The authors of this paper thank the University of Alicante for the gran<sup>t</sup> that allowed part of this research.

**Conflicts of Interest:** The authors declare no conflicts of interest.
