For instance, PPM indicates "components for every million". If you discover out the concentration of NO2textual content NO _2NO2​ is equal to 1 ppm, it means that if you're taking a "sample" of air and divide it into a million elements, one of these will encompass NO2textual content NO _2NO2​. https://freeppmcalculator03680.blogunteer.com/35629992/facts-about-online-ppm-calculator-revealed