One example is, PPM indicates "pieces for each million". If you find out that the focus of NO2text NO _2NO2 is equivalent to 1 ppm, it signifies that if you are taking a "sample" of air and divide it into one million elements, one of them will consist of NO2text https://online-ppm-calculator71468.mybuzzblog.com/16547954/the-best-side-of-free-ppm-calculator