By way of example, PPM suggests "pieces for each million". If you find out which the concentration of NO2text NO _2NO2​ is equal to one ppm, it signifies that if you're taking a "sample" of air and divide it into a million areas, one of them will encompass NO2text NO https://sethhevka.blogkoo.com/the-best-side-of-free-ppm-calculator-56041943