fugitive emissions are Emissions that do not come from smokestacks, tailpipes, or any other Emissions collection system. Air Pollution escaping from leaky pipes in an industrial plant is an example of a fugitive emission.
Other /More definition:
Fugitive emissions are Unintended gas leaks from the processing, transmission, and/or transportation of fossil fuels, CFCs from refrigeration leaks, SF6 from electrical power distributor, etc.