Good response was observed in simultaneously using six RAD7 detectors at high radon concentrations, temperatures and relative humidity conditions. RAD7 detectors were tested in laboratory using radon chambers from 13 up to 59.8 kBq m⁻³, statistical analysis allows to distinct between counting errors and radon variation. RAD7 detectors were exposure to extreme environmental conditions at uranium flat mine. High radon concentration in soil from a confined uranium mineral was 274.3 kBq m⁻³ at 44°C temperature and 20% relative humidity. Inside uranium mine radon increased from 1.0 up to 88.5 kBq m⁻³.

Activity concentration of 238 U and 232Th and their decay products are assessed in soil at three hydrocarbon zones to determine the baseline before further fracking studies. The range of activity concentration for the three zones was 238U (from 9.2 ± 0.5 to 115.8 ± 7.5) Bq kg−1, 228Ra (from 8.3 ± 2.0 to 50.0 ± 4.4) Bq kg−1 and 226Ra (from 24.1 ± 2.3 to 86.8 ± 4.7) Bq kg−1; which are comparable to the global average values reported by UNSCEAR in soil. Similar activity-concentration patterns for 238U decay series and 232Th decay series for the three zones indicate no previous industrial action. This baseline is useful to assess a possible enrichment of Naturally Occurring Radioactive Materials if industrial activities take place in the future.

Environmental radioactivity study was performed in unconventional hydrocarbons areas for the first time in Mexico, where four unconventional hydrocarbon exploratory wells (UHEW) are planned. This study assesses natural radiological conditions in areas around UHEW. Equivalent dose rate distribution displayed in Geographic Information System (GIS) had a maximum of 1.83 mSv a⁻¹ and minimum of 0.04 mSv a⁻¹, GIS was also used for introducing land usage, water resources and population occupancy. Measurements of gross alpha and gross beta in water were below the national permissible limits for drinking water 0.5 and 1.0 Bq L⁻¹ respectively, even though samples do not correspond to drinking water. Evaluation of ²³⁸U and ²²⁶Ra in groundwater were below minimum detectable concentration 1.3 and 1.0 Bq L⁻¹, respectively. This study provides a radiological baseline for the impact of future industrial activities, especially if exploitation of unconventional hydrocarbons produces naturally occurring radioactive material.

¹³⁷Cs activity concentration in soil was analyzed yearly for 13 years (2010–2022) in an undisturbed area in Mexico. The temporal variation at 17 sampling points is consistent with the natural radioactive decrease of ¹³⁷Cs, excluding increased activity concentration detected after the Fukushima accident at 4 sampling points. Geospatial analysis was permitted to obtain ¹³⁷Cs activity concentration distributions for each year. The highest ¹³⁷Cs activity concentration was found at higher topography levels and close to intermittent water streams: 87.1 ± 5.5 Bq kg⁻¹ for the year 2011, which increased to 135.5 ± 14.5 Bq kg⁻¹ for the year 2013, and then ¹³⁷Cs decreased down to 46.4 ± 4.0 Bq kg⁻¹ by the year 2022. The lowest ¹³⁷Cs activity concentration was in the range of 0.6 ± 0.1 Bq kg⁻¹ to 13.5 ± 1.0 Bq kg⁻¹ at the points far from the undisturbed area, probably due to anthropogenic activities.