Related by context. Frequent words. (Click for all words.) 61 tailpipe emissions 54 greenhouse gas emission 53 emission reduction 52 curbing greenhouse gas 50 Board CARB 49 greenhouse gas 49 reduce greenhouse gas 49 greenhouse gas emissions 48 emission 48 regulate greenhouse gases 48 global warming gases 47 regulating greenhouse gases 47 emissions 47 regulate greenhouse gas 46 CARB 46 greenhouse gases 46 polluters 44 reducing greenhouse gas 44 Kyoto accord 44 greenhouse emissions 44 tailpipe 44 emission reductions 44 Clean Air 44 carbon dioxide emission 43 GHG emissions 43 regulate carbon dioxide 43 reduce carbon emissions 43 CAFE standards 43 regulations 43 emit greenhouse gases 42 AQMD 42 exhaust emissions 42 carbon dioxide emissions 42 carbon emission 42 GHG 42 impose stricter 41 Environmental Protection Agency 41 EPA 41 cleaner burning 41 cleaner fuels 41 Emissions 41 mercury emissions 41 greenhouse gasses 41 Automakers 41 GHGs 41 reducing carbon emissions 41 carbon emissions 40 Kyoto Treaty 40 heat trapping emissions 40 REAL ID Act 40 nitrogen oxide emissions 40 greenhouse gas GHG emissions 40 enacting 40 Kyoto treaty 40 greenhouse gas emitters 40 legislation 40 emission norms 40 laws 40 Kyoto Protocol 40 mandating 39 unilateral sanctions 39 Kyoto protocol 39 heat trapping gases 39 reducing CO2 emissions 39 gases blamed 39 enact 39 zero emission 39 air pollution 39 combating global warming 39 smog 38 mercury pollution 38 Air Pollution Control 38 automakers 38 stricter 38 Renewable Portfolio Standard 38 enforce 38 carmakers 38 CO2 emissions 38 pollution 38 pollutant emissions 38 emit carbon dioxide 37 RGGI 37 emitters 37 polluting industries 37 CO2 emission 37 Regional Greenhouse Gas 37 rules 37 states 37 Kyoto Protocol expires 37 Kyoto pact 37 Global Warming Solutions 37 carbon dioxide CO2 emissions 37 NOx 37 Climate Initiative 37 forest thinning 37 Greenhouse Gas 36 stringent 36 carbon emitters 36 Fuel Efficiency 36 roadless rule 36 mandates