By way of example, PPM indicates "areas for every million". If you find out the focus of NO2text NO _2NO2​ is equal to one ppm, it means that if you're taking a "sample" of air and divide it into 1,000,000 areas, one of them will consist of NO2textual content NO https://free-ppm-calculator72604.digitollblog.com/36530936/rumored-buzz-on-ppm-calculator