Street-side trees in cities are characterized by poor health, with high salinity and pH, that leads to an early death. The main reason is soil salinity caused by winter road maintenance using salt (NaCl). Our research comprised three species of trees. A dependency was determined between their vigour and health and the content of biogenic elements, typical pollution, and indicators of ionic balance. It was demonstrated that disturbances of ionic balance had a negative effect on the health of leaves and trees. Increasing the amounts of chlorine and sodium in the leaves did not have any influence on the content of phosphorus, potassium, nitrogen, and sulphur. The content of calcium was slightly lowered, and that of magnesium was lowered to a large extent. The leaves containing over 15% chlorine in the sum of all elements studied, expressed in equivalent values, were characterized by noticeable disturbances in their growth and health.