Reduced O2 in Air Due to Burning Fossil Fuels

[jreelawg]

Burning stuff reduces the amount of o2 in the air. How much oxygen gets trapped in CO2 due to burning fossil fuels etc? Plants take CO2 and free the oxygen, but now days we have less plants, while burning more stuff. I'm thinking that there must be less O2 present in the air than before industrialization, but what is the magnitude, and is there any reason to worry about this issue becoming a future problem?

 

[mgb_phys]

CO2 is going up by about 2ppm/year, but is still a very small part of the atmosphere.
Only 0.04% (400ppm) is CO2, Oxygen makes up about 21% or (210,000PPM) the rest is nitrogen.

CO2 is toxic above about 0.5% and fatal at around 5%, so at current rates you will die in 25,000 years if nothing else happens.