As an example, PPM signifies "components per million". If you find out which the focus of NO2textual content NO _2NO2​ is equivalent to 1 ppm, it implies that if you take a "sample" of air and divide it into a million parts, one of them will encompass NO2text NO _2NO2​. https://felixprdnw.develop-blog.com/44083629/facts-about-ppm-calculator-revealed