Trees alone can produce enough oxygen to support all human oxygen needs in North America. Trees are important and benefit the environment. A mature leafy tree produces as much oxygen in a season as 10 people inhale in a year. This quote was by an Arbor Day Foundation report. For a number of reasons, including tree availability and other photosynthetic plants, human consumption of oxygen produced just by trees can vary dramatically.
There is also some question as to how many mature leafy trees are in the United States, but a rough estimate using United States Forest Service (FIA) data would be around 1.5 billion that have reached maturity (assuming they are 20 years old or older). There are approximately three mature trees for every person in the United States… more than enough.
Other Tree Oxygen Estimations
Here are some other quotes from different sources which may be more or less conservative than my report:
- "A single mature tree can absorb carbon dioxide at a rate of 48 lbs./year and release enough oxygen back into the atmosphere to support 2 human beings." - McAliney, Mike. "Arguments for Land Conservation: Documentation and Information Sources for Land Resources Protection," Trust for Public Land, Sacramento, CA, December, 1993.
- "On average, one tree produces nearly 260 pounds of oxygen each year. Two mature trees can provide enough oxygen for a family of four." -Canada's environmental agency, Environment Canada.
- "Mean net annual oxygen production (after accounting for decomposition) per hectare of trees (100% tree canopy) offsets oxygen consumption of 19 people per year (eight people per acre of tree cover), but ranges from nine people per hectare of canopy cover (four people/ac cover) in Minneapolis, Minnesota, to 28 people/ha cover (12 people/ac cover) in Calgary, Alberta." - U.S. Forest Service and International Society of Arboriculture joint publication.
Several of these sources suggest that it all depends on the tree species and their local populations. Other things that will increase oxygen availability to humans is a tree's health and where you live when computing tree oxygen availability per person.