By way of example, PPM signifies "components per million". If you discover out which the concentration of NO2text NO _2NO2​ is equivalent to one ppm, it means that if you're taking a "sample" of air and divide it into a million components, one of them will encompass NO2text NO _2NO2​. https://online-ppm-calculator39381.free-blogz.com/83918580/not-known-factual-statements-about-online-ppm-calculator