For example, PPM suggests "parts for each million". If you discover out which the concentration of NO2textual content NO _2NO2​ is equivalent to 1 ppm, it means that if you're taking a "sample" of air and divide it into 1,000,000 parts, one of these will include NO2text NO _2NO2​. PPT https://joycel987eox7.blog-ezine.com/profile