Related by context. Frequent words. (Click for all words.) 67 pollution 61 air pollution 57 polluting 57 pollute 56 greenhouse gasses 55 pollutant 54 CO2 54 pollutes 53 pollutants 53 CO2 emissions 52 GHGs 51 smog 51 polluted 51 Pollution 51 particulate emissions 50 CO2 emission 50 carbon emissions 50 exhaust emissions 50 emissions 50 carbon dioxide emission 50 emission 49 greenhouse gases 49 carbon dioxide emissions 49 exhaust fumes 49 polluter 49 particulates 49 carbon emission 48 Carbon Dioxide 48 greenhouse emissions 48 acid rain 48 particulate pollution 47 carbon dioxide 47 NOx emissions 47 particulate matter 47 greenhouse gas emissions 47 diesel fumes 46 greenhouse gas 45 VOCs 45 Greenhouse gases 45 polluters 45 NOx 45 burning fossil fuels 45 tailpipe emissions 45 GHG emissions 44 toxic waste 44 global warming 44 SO2 44 traffic congestion 44 Emissions 44 fossil fuel 44 congestion 43 carbon dioxide CO2 emissions 43 mercury pollution 43 reduce carbon emissions 43 ozone pollution 43 effluents 43 carbon dioxide CO2 43 environmental degradation 43 carbon dioxide emitted 43 greenhouse gas emission 43 noxious fumes 43 sulfur dioxide 42 polluting industries 42 emit greenhouse gases 42 gasses 42 noxious 42 reducing CO2 emissions 42 nitrogen oxides 42 Global warming 42 particulate 42 diesel exhaust 42 tree huggers 42 greenhouse gas GHG emissions 42 externalities 42 carbon emitting 42 carbon footprint 42 stink 42 reducing carbon emissions 42 soil erosion 41 Carbon dioxide 41 nitrogen oxide emissions 41 smoggy 41 sulfur dioxide emissions 41 waste 41 Global Warming 41 nitrogen oxide 41 fossil fuels 41 mercury emissions 40 carbon footprints 40 toxic chemicals 40 thats 40 water vapor 40 gases 40 GHG 40 noise 40 crud 40 littering 39 urban sprawl 39 toxins 39 Environmentally 39 toxics