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Question: How many plants are needed to make enough oxygen for one person for one hour ? We are experimenting with Anacharis plants. Replies: The problem can be solved when broken down into smaller questions: 1. How much oxygen does a person need in an hour? 2. How much oxygen does a plant produce in an hour? 3. Based on the above, how many plants will provide the oxygen needs of the person for the hour? Here is the solution to the first question: A resting, healthy adult on an average, cool day breathes in about 53 liters of oxygen per hour. An average, resting, health adult breathes in about 500 mL of air per breath. This is called the normal tidal volume. Now, 150 mL of this air will go to non- functioning areas of the lung, called the "dead space." The average breath rate for this average person is 12 breaths per minute. So, the amount of air breathed in by the person which is available for use is 12 x (500 mL -150...

How much do YOU think a tree is worth?? And how does one measure the value and then convert the result to monetary terms? Here's one way..... When Sue Rostas, Communications Officer for the Kooragang Wetland Rehabilitation Project, received a letter from Carrington Public school student, Michael Wilson, it set her thinking. Michael asked what was the economic value of a tree. He suggested we assume a value of $1 a day for the amount of oxygen that a tree produces. A tree thus produces $365 worth of oxygen per year or a total of $36,500 over 100 years (and that's not allowing for inflation!) Sue wondered how close to the mark was this assumed dollar value. A few phone calls to Assoc. Prof. Tlna Offler, University of Newcastle, and Bill Nethery, State Forests of NSW, plus some library work revealed some startling but often overlooked facts about the true value of trees. Michael's assumption had in fact greatly underestimated the value of trees. The true value (considering on...