For instance, PPM means "pieces for every million". If you find out which the concentration of NO2text NO _2NO2​ is equal to one ppm, it ensures that if you're taking a "sample" of air and divide it into 1,000,000 components, one of them will consist of NO2textual content NO _2NO2​. https://toddk654wgp4.wikienlightenment.com/user