For instance, PPM suggests "elements for each million". If you discover out the focus of NO2text NO _2NO2​ is equivalent to 1 ppm, it ensures that if you are taking a "sample" of air and divide it into 1,000,000 components, one of these will consist of NO2textual content NO _2NO2​. https://online-ppm-calculator75274.nizarblog.com/36932908/facts-about-online-ppm-calculator-revealed