How does a person know what ppm of carbon dioxide exists if the hand pump detector tubes are scaled by volume percentage?

0.1 percent = 1,000 ppm 1 percent is 10,000 ppm. 2 percent is 20,000 ppm 3 percent is 30,000 ppm 10 percent is 100,000 ppm etc. Take the percent, move the decimal point 4 places to the right, and you have the ppm. You take it from here.