For example, PPM implies "areas for each million". If you discover out the concentration of NO2textual content NO _2NO2 is equal to 1 ppm, it means that if you are taking a "sample" of air and divide it into 1,000,000 components, one of these will encompass NO2textual content NO _2NO2. https://elliotttlylv.pointblog.net/top-latest-five-free-ppm-calculator-urban-news-83023256