By way of example, PPM signifies "sections for each million". If you find out the concentration of NO2text NO _2NO2​ is equivalent to one ppm, it means that if you are taking a "sample" of air and divide it into a million parts, one of them will consist of NO2text https://johnathanvnzmw.shoutmyblog.com/35772287/5-simple-statements-about-ppm-calculator-explained