Hectare : Unit of area equal to 10 000 square metres (m2) in any shape (e.g. rectangles 10 m x 1000 m or 25 m x 400 m; square 100 m x 100 m; or other regular and irregular shapes).
Health and Safety Executive (HSE), Glossary of Abbreviations: Planning Advice for Developments Near Hazardous Installations PADHI HSE's Land Use Planning Methodology, HSE, Merseyside, England, UK 2011. www.hse.gov.uk/landuseplanning/padhi.pdf, (Hlth and Sfty - Brit) {714}