Such as, PPM means "pieces for every million". If you find out the focus of NO2textual content NO _2NO2​ is equivalent to 1 ppm, it means that if you take a "sample" of air and divide it into one million components, one of these will encompass NO2text NO _2NO2​. He https://donovanxhloo.vblogetin.com/42554280/facts-about-ppm-calculator-revealed