For example, PPM indicates "elements per million". If you discover out the focus of NO2text NO _2NO2​ is equivalent to 1 ppm, it implies that if you take a "sample" of air and divide it into 1,000,000 areas, one of them will consist of NO2text NO _2NO2​. If percentages, for https://andregfzri.blog-mall.com/37419527/free-ppm-calculator-options