By way of example, PPM indicates "pieces for every million". If you discover out the focus of NO2textual content NO _2NO2​ is equal to 1 ppm, it signifies that if you take a "sample" of air and divide it into 1,000,000 parts, one of them will encompass NO2text NO _2NO2​. https://henryi677nfv8.blogdeazar.com/profile