For instance, PPM signifies "elements for every million". If you find out that the concentration of NO2text NO _2NO2​ is equal to 1 ppm, it means that if you're taking a "sample" of air and divide it into 1,000,000 components, one of them will consist of NO2text NO _2NO2​. Rijk https://online-ppm-calculator77384.mybloglicious.com/56726712/the-fact-about-online-ppm-calculator-that-no-one-is-suggesting