As an example, PPM signifies "areas for each million". If you find out that the concentration of NO2textual content NO _2NO2​ is equivalent to 1 ppm, it means that if you take a "sample" of air and divide it into one million pieces, one of these will consist of NO2textual https://reidoyawv.qodsblog.com/36774214/a-secret-weapon-for-free-ppm-calculator