For instance, PPM suggests "parts per million". If you find out which the concentration of NO2text NO _2NO2​ is equivalent to 1 ppm, it means that if you are taking a "sample" of air and divide it into 1,000,000 areas, one of these will include NO2text NO _2NO2​. Components Per https://cristianuslbr.blogsvirals.com/35693706/the-best-side-of-free-ppm-calculator