Related by context. Frequent words. (Click for all words.) 55 pollution 51 emission 50 polluting 49 environmental 48 air pollution 46 Clean Air 45 AQMD 45 cleaner burning 45 exhaust emissions 45 tailpipe emissions 45 greenhouse gas 44 mercury emissions 44 cleaner fuels 44 emissions 43 environmentally harmful 43 diesel powered 43 pollutants 42 environmentally friendly 42 polluters 42 coal fired 42 Environmental Protection Agency 42 smog 42 carbon dioxide emission 41 toxic pollutants 41 diesel exhaust 41 EPA 41 particulate emissions 41 emission reduction 41 Clean Water Act 41 greenhouse gas emission 41 pollutant 41 combustion engines 40 mercury pollution 40 smokestacks 40 pollute 40 incinerators 40 environmentally damaging 40 Environmentalists 40 diesel engines 40 polluting industries 40 selective catalytic reduction 40 Pollution 40 Environmentally friendly 39 stricter 39 greenhouse gases 39 environmentally unfriendly 39 Tittel 39 carbon dioxide emissions 39 catalytic converters 39 mandating 39 environmentalists 39 scrubbers 39 nitrogen oxide emissions 39 Emissions 38 Emission 38 sulfur dioxide emissions 38 carbon emission 38 diesel 38 stringent 38 sulfur dioxide 38 retrofitting 38 greenhouse gasses 38 greenhouse gases emitted 38 toxics 38 conservation 38 greenhouse gas emissions 38 CO2 emission 38 scrubber 38 acid rain 38 automobiles 38 emit greenhouse gases 37 environmentally sensitive 37 federally mandated 37 environmentally sound 37 regulate greenhouse gases 37 Sierra Club 37 zero emission 37 toxic chemicals 37 cleaner 37 retrofit 37 wastewater discharge 37 nitrogen oxide 37 coal gasification 37 boilers 37 CARB 37 reduce carbon emissions 37 global warming gases 37 filtration 37 waste disposal 37 polluter 37 toxic substances 36 internal combustion engines 36 harmful pollutants 36 ecofriendly 36 greenhouse emissions 36 environmentally destructive 36 hazardous chemicals 36 Stricter 36 Board CARB 36 carbon dioxide 36 diesels