Parts Per Million (PPM) 03 : Parts of gas or vapour per million parts of air by volume at room temperature. For example, 1 cubic centimetre of gas in 1 million cubic centimetres of air has a concentration of 1 PPM
Industrial Accident Prevention Association (IAPA), Centre for Health & Safety Innovation, Glossary of Occupational Health & Safety Terms, Ontario, Canada 2007. http://www.iapa.ca/pdf/iapa_glossary.pdf, (Occupn Hlth and Sfty - Canad) {93}