Such as, PPM signifies "areas for every million". If you discover out the concentration of NO2text NO _2NO2​ is equivalent to 1 ppm, it signifies that if you take a "sample" of air and divide it into one million elements, one of them will include NO2textual content NO _2NO2​. PPT https://ppmcalculator94815.fitnell.com/77513899/the-single-best-strategy-to-use-for-online-ppm-calculator