- Atmospheric Protection/Air Quality Control/Air Pollution 4
- Ecotoxicology 3
- Waste Water Technology / Water Pollution Control / Water Management / Aquatic Pollution 3
- Environment, general 2
- Environmental Chemistry 2
- Environmental Health 2
- Monitoring/Environmental Analysis 2
- Ecology 1
- Environmental Law/Policy/Ecojustice 1
- Environmental Management 1
- Industrial Pollution Prevention 1
- Pollution, general 1