Exhaust gas or flue gas is emitted as a result of the combustion of fuels such as natural gas, gasoline (petrol), diesel fuel, fuel oil, biodiesel blends, or coal. According to the type of engine, it is discharged into the atmosphere through an exhaust pipe, flue gas stack, or propelling nozzle. It often disperses downwind in a pattern called an exhaust plume.
Steam from tailpipe of cold car
Automobile exhaust
What looks like exhaust from jet engines is actually contrail.
Smog in New York City as viewed from the World Trade Center in 1988
Flue gas is the gas exiting to the atmosphere via a flue, which is a pipe or channel for conveying exhaust gases, as from a fireplace, oven, furnace, boiler or steam generator. It often refers to the exhaust gas of combustion at power plants. Technology is available to remove pollutants from flue gas at power plants.
Flue gas from London's Bankside Power Station, 1975
Before flue-gas desulfurization was installed, emissions from Four Corners Generating Station, New Mexico contained excessive amounts of sulfur dioxide.