One example is, PPM suggests "components for every million". If you discover out the focus of NO2textual content NO _2NO2​ is equivalent to one ppm, it means that if you are taking a "sample" of air and divide it into one million pieces, one of these will include NO2textual content https://donovandewsk.targetblogs.com/37155463/ppm-calculator-things-to-know-before-you-buy