World Health Organization 80 prevention & control 54 Nepal 53 standards 52 Public Health 46 Series 46 Environmental health 45 Health aspects 43 Environmental aspects 40 Water quality 39 Water Microbiology 38 Water Supply 38 Pollution 37 Gezondheid 36 Quality Control 36 Water 36 Water Pollution 36 Water quality management 36 Guidelines 29 Environmental exposure 27 Prevention 27 Knowledge 15 Research 15 Risk assessment 15 World health 15 Kathmandu 14 methods 14 Child 13 Mortality 12 Public health 12