Assessment by portable gamma spectrometry of the radiological hazard associated with built environments in northeastern Mexico

Abstract

The radiological hazard associated with the buildings of Nueva Rosita (northeastern Mexico) was assessed by gamma spectrometry measurements. Using a Handheld Gamma-Ray Spectrometer, the potassium, uranium, and thorium concentrations were measured. Also, four radiological indices are calculated: the absorbed dose rate (D), the annual effective dose equivalent (E), the hazard index (H), and the excess lifetime cancer risk (ELCR). Inside and outside of public buildings and dwellings, urban space gamma-ray measurements were carried out. According to the year they were built, the public buildings and dwellings of Nueva Rosita were classified into three groups (new, moderately old, and old buildings). Using the activity concentration of radioelements and calculated radiological hazard indices, the studied environments were classified into three classes of radiological hazards. This last classification was carried out by comparing the values of radionuclides and indices with world averages. Class 1 characterizes the environments with a low radiological hazard, class 2, the environments with a moderate radiological hazard, and class 3, the environments with a high radiological hazard. The highest hazard is located indoors in buildings and the lowest hazard occurs in urban spaces. The old buildings have the highest hazard both indoors and outdoors, due to the high content of uranium (102–111 Bq kg⁻¹) and thorium (70–144 Bq kg⁻¹) and the values of D (84–261 nGy h⁻¹), E (0.1–1.28 mSv y⁻¹), H (0.5–1.09), and ELCR (0.35–4.48 × 10^–3) that can exceed up to four times their world average.