In the northern hemisphere, atmospheric levels of carbon dioxide gas are maximum during late winters and spring months. The increased carbon dioxide levels of atmosphere are due to lowest vegetative uptake of the gas by plants for photosynthesis.
On the other hand, early autumn months in the hemisphere exhibit low carbon dioxide levels. This is due to the increased photosynthetic activity of native plants during the month of summers which in turn reduces the concentration of carbon dioxide in air.
parenthetical instructions under CPT® code 33690 include thus: For right and left pulmonary artery banding in a single ventricle {for example, hybrid approach stage 1} , use 33620) and (Do not report modifier 63 in conjunction with 33690)
