Short-Term Changes in Weather and Space Weather Conditions and Emergency Ambulance Calls for Elevated Arterial Blood Pressure

Circadian rhythm influences the physiology of the cardiovascular system, inducing diurnal variation of blood pressure. We investigated the association between daily emergency ambulance calls (EACs) for elevated arterial blood pressure during the time intervals of 8:00-13:59, 14:00-21:59, and 22:00-7:59 and weekly fluctuations of air temperature (T), barometric pressure, relative humidity, wind speed, geomagnetic activity (GMA), and high-speed solar wind (HSSW). We used the Poisson regression to explore the association between the risk of EACs and weather variables, adjusting for seasonality and exposure to CO, PM10, and ozone. An increase of 10 degrees C when T > 1 degrees C on the day of the call was associated with a decrease in the risk of EACs during the time periods of 14:00-21:59 (RR (rate ratio) = 0.78; p < 0.001) and 22:00-7:59 (RR = 0.88; p = 0.35). During the time period of 8:00-13:59, the risk of EACs was positively associated with T above 1 degrees C with a lag of 5-7 days (RR = 1.18; p = 0.03). An elevated risk was associated during 8:00-13:59 with active-stormy GMA (RR = 1.22; p = 0.003); during 14:00-21:59 with very low GMA (RR = 1.07; p = 0.008) and HSSW (RR = 1.17; p = 0.014); and during 22:00-7:59 with HSSW occurring after active-stormy days (RR = 1.32; p = 0.019). The associations of environmental variables with the exacerbation of essential hypertension may be analyzed depending on the time of the event.