Ppm explained

Ppm?

Currently, in 2017, CO2 levels in our atmosphere are just over 410 ppm. The safe level of carbon dioxide in the atmosphere is 350 parts per million. 

Parts per million (ppm) is the value used to measure concentrations of carbon dioxide in our atmosphere. Imagine a pie sliced in one million pieces. 400 ppm stands for 400 pieces of this pie.