A low pressure system has. For some people, low blood pressure causes no problems. For others, it can cause dizziness and fainting or be life-threatening. Optimal blood pressure is less than /80 (systolic/diastolic). In healthy people, low blood pressure without any symptoms is not usually a. In meteorology, a low-pressure area, low area or low is a region where the atmospheric pressure is lower than that of surrounding locations. Low-pressure. Low blood pressure is a reading of less than 90/60mmHg. It does not always cause symptoms, but you may need treatment if it does. Low blood pressure, also called hypotension, is blood pressure low enough that the flow of blood to the organs of the body is inadequate and symptoms and/or. Blood pressure is considered low when the top blood pressure reading is lower than 90 mm Hg (systolic) and the bottom number is lower than. Areas of high and low pressure are caused by ascending and descending air. As air warms it ascends, leading to low pressure at the surface. As air cools it. The slightly inward moving air in low pressure causes air to converge and since it can't move downward due to the surface, the air is forced. Symptoms of low blood pressure · Dizziness or lightheadedness · Nausea · Fainting (syncope) · Dehydration and unusual thirst · Dehydration can.