Introduction: 20% of Bulgarians die of ischemic heart disease. A study was conducted in order to get more information on whether and to what extent mortality from ischemic disease in Bulgaria is related to external causes – in particular to the corpuscular solar radiation.
Material and methods: Data for mortality of ischemic heart disease from the Bulgarian National Statistical Institute were used. Data on solar corpuscular radiation was obtained from NOAA site. Correlation and regression analysis were used to process the data.
Results: Between the annual number of protons with energy above 1 MeV and alpha particles with an energy of 4 to 10 MeV on the one hand and the male and female ischemic disease mortality for Bulgaria, forms I20 to I25 according to the International Classification of Diseases 10th revision, has a high statistically significant correlation. The dependence of female ischemic heart disease on the alpha particle flux was with the highest correlation coefficient: 0,939, a statistical significance level of 0,001. The mortality from ischemic disease in Bulgaria is negatively correlated with the horizontal component of the geomagnetic field in Bulgaria (for male mortality, the correlation coefficient is -0.888, the level of statistical significance 0.001). There are no statistically significant correlations between mortality from ischemic heart disease in Bulgaria on the one hand and the average annual number of sunspots and x-ray radiation (0.1 – 0.8 nm) of the geostationary orbit, on the other hand. There are no statistically significant correlations between galactic cosmic radiation and mortality from ischemic heart disease in Bulgaria. Examples are given for a date interval with intensive proton flux and ischemic mortality, correlated with it.
Discussion: The results indicate an existence of unknown phenomenon–a causal relationship between mortality from ischemic heart disease in Bulgaria on the one hand, and the fluxes of solar corpuscular radiation on the other. The contribution of this phenomenon to the risk of mortality from ischemic heart disease in Bulgaria is about 6 – 10%. This phenomenon is observable also in the other small area mid-latitude countries.
Mortality; Ischemic heart disease; Solar positive corpuscular radiation; Proton flux; Satellite measurement; Risk of death