Effect of Temperature and Environmental Radioactivity on Respiratory Diseases

Radon is a radioactive gas that has no smell, colour or taste and them its half-life are approximately 3.825 days. It is produced from the natural radioactive decay of uranium, which is found in all rocks and soils. Is the heaviest of all noble gases and has a total of 36 isotopes ranging from ¹⁹³Rn to ²²⁸Rn. Radon is a naturally occurring radioactive gas which may be found in high concentrations in indoor environments, such as homes and workplaces. Radon signals at shallow depths are mainly influenced by environmental parameters, such as atmospheric pressure, temperature, groundwater level, and precipitation. The values observed by several researchers for the seasonal and diurnal oscillations of subsurface radon concentrations, show correlations between this gas and atmospheric temperature. Radon concentrations were highest during heatwaves lasting several days and exhibited seasonal trends (winter and summer). Since 1900, radon has been widely studied including for its impact on human health, because inhalation of radon is the largest source of exposure to ionizing radiation for the world's population, contributing more than 40% to the effective dose of environmental radioativity.

However, the literature is poor in the correlation between environmental radioativity and respiratory diseases. This work is assumed in the insular context of the Azores - Portugal. The base information (epidemiological and environmental radioativity) used in this work corresponds to daily data from 2010 to 2020 and provided by the Statistics Service of the Hospital da Horta (Açores) and The Network for the Continuous Surveillance of Radioactivity in the Environment, with a fixed station in Ponta Delgada (São Miguel_Azores), whose management being the responsibility of the Portuguese Environment Agency.

With the selected data, monthly averages were calculated and a statistical analysis was performed using the SPSS software (Statistical Package for the Social Sciences) version 28 for Windows. The null hypothesis (H₀)_ “there is no correlation between environmental radioativity levels and the number of hospitalized individuals by respiratory diseases”. The alternative hypothesis (Ha)_”there is a correlation between environmental radioativity levels and the number of hospitalized individuals by respiratory diseases” was formulated. The level of significance (α) to accept or reject the null hypothesis was fixed a α ≤ 0.05. Pearson's correlation coefficient was used for inferential statistics. It was obtained, r =0.486 and p < 0.001, being r the Pearson correlation coefficient and p the p_value. It was found that p < α, therefore, the null hypothesis was rejected with a confidence level of 95%.

The correlation between environmental radioativity levels and the value of the monthly averages of respiratory pathologies is statistically significant, positive and moderate (r = 0.486, p < 0.001). Thus, as environmental levels of environmental radioativity increase, also the number of pacients with respiratory pathologies increase. The practical study’s conclusions show an interesting relationship between hospitalization patterns and environmental radioativity levels.