Gas exchange is the delivery of oxygen from the lungs to the bloodstream, and the elimination of carbon dioxide from the bloodstream to the lungs. It occurs in the lungs between the alveoli and a network of tiny blood vessels called capillaries, which are located in the walls of the alveoli.
Admitted for 180 days â Canadians admitted in âVisitor for Pleasureâ or B-2 status without a B-2 visa in hand are deemed to be admitted for 180 days under current US Customs and Border Protection (CBP) interpretation of the rules.
Hunnisett said Canadians spending more than 120 days in the U.S for three years or more in a row can extend their stay limit to 182 days and avoid being considered a U.S. resident for tax purposes by filling out a Closer Connection Exception Statement form detailing their close ties to Canada annually.