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.
An average skyscraper is usually a multistory building with an architectural height of at least 100 meters. The average height seems to be increasing with time. The Council on Tall Buildings and Urban Habitat has reported that 600 meters seem to be the new 300 meters, with the increasing demand of taller buildings.