As an example, PPM means "sections per million". If you find out the focus of NO2textual content NO _2NO2​ is equivalent to 1 ppm, it implies that if you're taking a "sample" of air and divide it into 1,000,000 sections, one of them will consist of NO2text NO _2NO2​. Rijk https://friedrichk997gqz8.angelinsblog.com/profile