As an example, PPM means "components for every million". If you discover out that the concentration of NO2text NO _2NO2​ is equal to one ppm, it ensures that if you're taking a "sample" of air and divide it into one million pieces, one of them will encompass NO2text NO _2NO2​. https://ppm-calculator28271.fare-blog.com/36944456/online-ppm-calculator-secrets