Collocations for emission - noun

harmful, noxious, toxic
gaseous
automobile (esp. AmE), exhaust, tailpipe (AmE), vehicle
industrial
atmospheric
greenhouse gas
the Kyoto protocol on cutting greenhouse gas emissions

acid, carbon, carbon dioxide, lead, mercury, methane, sulphur/sulfur, etc.
global
global emissions of carbon dioxide

generate, produce
curb, cut, lower, minimize, reduce
We must take action to cut vehicle emissions.

eliminate
control, limit, regulate
offset
New power plants must offset emissions by funding climate-change projects.

measure, monitor

increase
decrease, fall

levels, rates

emissions from
measures to reduce harmful emissions from traffic