Related by context. Frequent words. (Click for all words.) 85 air pollution 77 pollutants 74 Pollution 70 pollutant 70 emissions 67 polluting 67 emission 65 greenhouse gases 65 smog 64 polluted 63 greenhouse gas emissions 63 carbon dioxide emissions 63 greenhouse emissions 62 carbon emissions 62 mercury emissions 62 acid rain 61 pollute 61 polluters 61 carbon emission 61 greenhouse gas 59 polluter 59 environmental 58 sulfur dioxide 57 CO2 emissions 56 Emissions 56 carbon dioxide 56 particulate matter 56 toxic chemicals 55 GHG emissions 55 emission reduction 54 CO2 54 environmental degradation 54 particulates 53 soot 53 global warming 52 contaminants 52 traffic congestion 51 emission reductions 51 EPA 51 soil erosion 51 Environmental Protection Agency 51 reduce carbon emissions 50 Clean Air 50 toxic waste 50 GHG 50 congestion 50 ozone 50 climate change 50 effluent 50 toxins 49 mercury 49 contamination 49 groundwater 49 volatile organic compounds 48 waterways 48 smokestacks 48 toxic substances 47 contaminant 47 sediment 47 coal fired 47 urban sprawl 47 silt 47 Clean Water Act 47 Air Quality 47 hazardous chemicals 47 hazardous waste 47 reducing carbon emissions 46 salinity 46 environmental impacts 46 carbon 46 environmentalists 46 hazardous substances 46 deforestation 45 stormwater 45 pesticide 45 pesticides 45 methane 45 arsenic 45 phosphorus 45 burning fossil fuels 45 benzene 44 phosphorous 44 sewage 44 noise 44 secondhand smoke 44 ecological 44 fossil fuel 44 cleaner 44 wetlands 44 algae 44 Water Quality 44 Environmental Quality 43 dioxin 43 gases 43 carbon footprint 43 odors 43 PCBs 43 fossil fuels 43 Environmental 43 invasive species 42 overfishing