Cardiovascular response as a marker of environmental stress caused by variations in geomagnetic field and local weather

We report the results of a physiological study that include ECG analysis, capillary blood velocity (CBV) data, and blood pressure (BP) measurements obtained under conditions of modified external magnetic field (MF). Each of eight volunteers was sequentially exposed to MFs of three different types for 22 h. A Helmholtz-like MF exposure system was used. The system was specially designed for long-term exposures of human beings to static and low frequency MFs. The MF of the first type reproduced an initially recorded geomagnetic storm (GS). The MF inductions of the other two types were about 55 and 49 mu T, which corresponded to the natural local magnetic background and a slightly decreased MF, respectively. In all three cases, the environmental magnetic fluctuations were suppressed by the active Helmholtz system. The variability of RR intervals was considered as a key indicator of cardiovascular response to the MFs and weather conditions. A time-frequency representation (TFR) and a frequency-frequency representation (FFR) were used for processing of the time series of RR intervals. It turned out that the transformation to TFR makes it possible to obtain the characteristic matrix of RR intervals; such a matrix can be used as a subject identifier. FFR was used to calculate correlations of RR intervals with the components of the MFs. The averaged correlation coefficients of RR intervals with the B x and B y components appeared significantly higher (p <0.001) during the Storm mode in comparison with control. Thus, it is shown that artificial geomagnetic storm can cause a detectable cardiovascular response. (C) 2019 Elsevier Ltd. All rights reserved.