Helping Aubie this week is Dr. Roland Dute, professor of Biological Sciences in AU's College of Sciences and Mathematics.

Dear Noori,

Oxygen is produced as
a waste product when plants use sunlight to convert carbon dioxide and water into food during the process of photosynthesis.The
amount of oxygen released
by a tree will depend upon
the amount of water present in the soil, whether the day is cloudy or sunny, and whether the tree is exposed directly to sunlight or shaded by other trees.

One estimate indicates that a large tree whose trunk is 39 inches in diameter at breast height releases 0.67 pounds (0.31 kilograms) of oxygen per day. A smaller tree of 9-12 inches diameter at breast height releases only 0.13 lbs (0.06 kg) per day. For comparison, according to NASA, a typical adult would use 1.85 lbs (0.84 kg) of oxygen gas per day in the process of respiration. From these numbers you can see the importance of trees to oxygen production on earth. According to the web site http://www.treepeople.org/, in one year an acre of trees can provide enough oxygen for 18 people.

Not only are trees important for oxygen manufacture, but also they improve our environment. Trees absorb odors and pollutant gases (nitrogen oxides, ammonia, sulfur dioxide and ozone) and filter particulates out of the air by trapping them in their leaves and bark. Trees also absorb carbon dioxide from the atmosphere, removing and storing the carbon while releasing the oxygen back into the air. Trees also help reduce erosion - on hillsides or stream slopes, trees slow water runoff and hold soil in place.

Thanks for your question,
Aubie and Dr. Dute