In most cases, pulmonary embolism is caused by a blood clot in the leg that breaks loose and travels to the lungs. A blood clot in a vein close to the skin is not likely to cause problems. But having blood clots in deep veins (deep vein thrombosis) can lead to pulmonary embolism.
St. Petersburg. 1  St. Petersburg is a city with a long and eventful history. 2  Altai is perhaps the most beautiful region of Russia. 3  Moscow is the capital of Russia, as well as the nationâs epicentre of arts, music, science, academics, and politics.  For a step back in time, Olkhon Island is a wonderful place to visit.
Largest Russian Citiies. Moscow is the largest city in Russia with a population of 12.1 million people, which also makes it the 11th largest city in the world. Saint Petersburg is the second largest Russian city, with 5.1 million people, making it the 50th largest city in the world.