As an example, PPM indicates "elements per million". If you discover out the concentration of NO2textual content NO _2NO2​ is equal to one ppm, it ensures that if you are taking a "sample" of air and divide it into 1,000,000 sections, one of them will encompass NO2text NO _2NO2​. Rijk https://norahc580zxu0.robhasawiki.com/user