are structures which provide ventilation for hot flue gases or smoke from
a boiler, stove, furnace or fireplace to the outside atmosphere.
Chimneys are typically vertical and tall structures to ensure that the gases
flow smoothly and through which combustion produced gases
are exhausted to the outside air.
There is no single standard defining minimum
mandatory requirements governing design and
installation of obstruction lighting; on the other
hand the most common and widespread
regulations are ICAO's and FAA's.