environment protection environment 75 environmental pollution 68 permanently sustainable development 60 ecology 55 air pollution 43 waste disposal services 38 more ... wastes 37 recycling of wastes 32 environmental management 24 unconventional energy sources 24 water courses 24 environmental law 21 ecosystems 19 environmental policy 17 water pollution 17 climatic changes 16 power engineering 15 atmosphere (biology) 15 water management 15 contaminants 14 health harmful substances 13 coolants 12 issues 12 landscape 12 Earth warming 12 construction materials 12 biofuels 11 sewerage 11 air cleanness monitoring 11 less ...