environment protection environment 71 environmental pollution 64 permanently sustainable development 54 ecology 53 air pollution 42 waste disposal services 38 more ... wastes 37 recycling of wastes 32 unconventional energy sources 24 water courses 24 environmental management 22 ecosystems 17 environmental law 17 water pollution 16 power engineering 15 atmosphere (biology) 15 water management 15 environmental policy 13 health harmful substances 13 contaminants 13 coolants 12 issues 12 climatic changes 12 Earth warming 12 biofuels 11 sewerage 11 air cleanness monitoring 11 landscape recultivation 11 construction materials 11 less ...