Depression increases your risk of a number of diseases and other conditions by, for example, increasing levels of stress hormones such as cortisol or adrenaline. Depression can affect the immune system, making it harder for your body to fight infection. Vaccinations are even less effective in people with depression.
The total surface area of the Earth is about 7008510000000000000â 510 million km2 (197 million sq mi). Of this, 70.8%, or 7008361130000000000â 361.13 million km2 (139.43 million sq mi), is below sea level and covered by ocean water.
Of this territory, 9,158,960 square kilometers (3,536,274 square miles) are land, while there are 470,131 square kilometers (181,517 square miles) of water. The United States is about one-half the size of Russia, and slightly larger than either Brazil or China. It shares long borders with both Canada (8,893 kilometers or 5,526 miles) and Mexico (3,326 kilometers or 2,066 miles).