When I was a boy, you couldn't say, "green fart, more gas than smoke," on the internet.
The Material on the emitter puts out many, very large, 99% transparent, green "streak" particles
The Force in the chor makes them waft upward
The turbulence on the Force makes the wafting motion more random
the Emission rate of the particles is keyframed in the Chor to vary the flow
There are many possible variations on the settings for different looks
GreenGas002.prj
GreenGas001.pre(render settings for above PRJ)
GreenGas001_h2000.mp4