For example, PPM implies "elements for every million". If you find out which the concentration of NO2textual content NO _2NO2​ is equivalent to one ppm, it implies that if you are taking a "sample" of air and divide it into one million areas, one of them will encompass NO2text NO https://free-ppm-calculator59246.glifeblog.com/35533575/online-ppm-calculator-secrets