For example, PPM implies "areas per million". If you discover out the concentration of NO2textual content NO _2NO2​ is equal to one ppm, it signifies that if you are taking a "sample" of air and divide it into a million parts, one of them will consist of NO2text NO _2NO2​. https://online-ppm-calculator26037.blogrelation.com/43045199/rumored-buzz-on-ppm-calculator