For instance, PPM means "pieces for every million". If you find out which the focus of NO2textual content NO _2NO2​ is equal to one ppm, it signifies that if you are taking a "sample" of air and divide it into 1,000,000 elements, one of these will encompass NO2text NO _2NO2​. https://taylorl653uem3.elbloglibre.com/profile