One example is, PPM means "parts for each million". If you find out which the concentration of NO2text NO _2NO2​ is equal to 1 ppm, it ensures that if you are taking a "sample" of air and divide it into a million elements, one of them will include NO2textual content https://archervyvqm.pointblog.net/free-ppm-calculator-an-overview-83020149