For instance, PPM means "elements per million". If you find out the focus of NO2text NO _2NO2​ is equal to 1 ppm, it ensures that if you take a "sample" of air and divide it into 1,000,000 pieces, one of these will consist of NO2textual content NO _2NO2​. Rijk is https://johni554aob9.blogoxo.com/profile