Breathing Zone 09 : The worker's breathing zone is described by a hemisphere of 300 mm radius extending in front of their face and measured from the midpoint of an imaginary line joining the ears
Ministry of Business, Innovation and Employment, Glossary of terms and acronyms, Wellington, New Zealand 2010. http://wwwsosh.govt.nz/resources/glossary-u.shtml, (Occupn Hlth and Sfty - Brit) {530}