Question: @ Cat how many trees do we need to get a full day of oxygen

Cat Scott ? answered on 13 Mar 2016:

Hi 369cmte45, this is a great question (but it’s quite complicated!) ? ?

The air is made of 20% oxygen (that’s one fifth of the total), so when we breathe in, our bodies don’t expect the air to be completely oxygen (in fact it is bad for you to breathe in pure oxygen). So you wouldn’t be able to collect all the oxygen coming from a tree and breathe it straight in.

If you have ever walked to the top of a very (very) big hill ?, you might have found that it starts to get a bit harder to breathe the higher you get – this is because there’s less oxygen in the air, and so less oxygen in each breathe you take. So whilst we shouldn’t breathe in pure oxygen, we need there to be nearly 20% in the air otherwise we will struggle to breathe.

Trees are very important for controlling the amount of oxygen in the air, in fact it goes up and down a bit over the course of the year because in the summer the trees are breathing lots of oxygen out, but in the winter many trees don’t have any leaves so this process doesn’t happen.

Some people have tried to work out how many trees would produce the amount of oxygen that one person would need over the course of a year and decided that it was 7 or 8 trees (about 0.02 trees per day!), but of course this depends on the type of tree and how quickly it’s growing.