Pulmonary edema occurs when the alveoli fill up with excess fluid seeped out of the blood vessels in the lung instead of air. This can cause problems with the exchange of gas (oxygen and carbon dioxide), resulting in breathing difficulty and poor oxygenation of blood.
Currently buildings are limited to a height of 200 meters and are subject to not contrasting the view of Mount Royal, the city's central green space, with the only exception being antennas and communication towers, that are allowed to reach 223 metres (732 ft) above mean sea level.
Chicago imposed a height limit of 40 meters in 1893, but New York raced ahead with large and tall blocks. Many of these, such as the Singer, Woolworth, MetLife and Chrysler buildings, tapered off with campanile towers, battling to be tallest in the world. The first skyscraper to break the half-kilometer mark, the world's tallest building between March 2004 and March 2010 is also one of the greenest -- certified LEED platinum in 2011.