For instance, PPM signifies "areas for every million". If you find out the focus of NO2textual content NO _2NO2​ is equal to one ppm, it signifies that if you are taking a "sample" of air and divide it into 1,000,000 elements, one of them will encompass NO2text NO _2NO2​. PPT https://ppm-calculator93567.blog4youth.com/37348731/new-step-by-step-map-for-free-ppm-calculator